{"id":2487,"date":"2016-09-18T22:24:33","date_gmt":"2016-09-18T22:24:33","guid":{"rendered":"http:\/\/fisicaevestibular.com.br\/novo\/?page_id=2487"},"modified":"2024-08-21T14:03:27","modified_gmt":"2024-08-21T14:03:27","slug":"estrutura-atomica-atomo-de-bohr","status":"publish","type":"page","link":"https:\/\/fisicaevestibular.com.br\/novo\/fisica-moderna\/estrutura-atomica-atomo-de-bohr\/","title":{"rendered":"Estrutura At\u00f4mica \u2013 \u00c1tomo de Bohr"},"content":{"rendered":"

Estrutura At\u00f4mica \u2013 \u00c1tomo de Bohr<\/b><\/span><\/span><\/span><\/p>\n

Breve hist\u00f3rico da descoberta do \u00e1tomo<\/b><\/span><\/span><\/span><\/p>\n

A partir <\/b><\/span><\/span><\/span>dos anos 1600 do <\/b><\/span><\/span><\/span>s\u00e9culo atual, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>busca do \u00e1tomo se tornou um exerc\u00edcio experimental <\/b><\/span><\/span><\/span>para <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

<\/a>diversos cientistas not\u00e1veis\u00a0<\/b><\/span><\/span><\/span>entre eles <\/b><\/span><\/span><\/span>est\u00e3o Robert Boyle, John Dalton, JJ Thomson, Ernest Rutherford e Niels Bohr.<\/b><\/span><\/span><\/span><\/p>\n

Boyle realizou experimentos com raios cat\u00f3dicos <\/b><\/span><\/span><\/span>(final do s\u00e9culo XIX) <\/b><\/span><\/span><\/span>cuja consequ\u00eancia <\/b><\/span><\/span><\/span>foi a <\/b><\/span><\/span><\/span>descoberta do el\u00e9tron carregado negativamente e as origens das primeiras no\u00e7\u00f5es da estrutura destes \u00e1tomos indivis\u00edveis.<\/b><\/span><\/span><\/span> <\/b>Thomson prop\u00f4s um modelo<\/b><\/span><\/span><\/span>, sugerindo<\/b><\/span><\/span><\/span>\"\"<\/p>\n

que <\/b><\/span><\/span><\/span>o \u00e1tomo tivesse uma estrutura semelhante a um pudim de ameixa, <\/b><\/span><\/span><\/span>ou seja, <\/b><\/span><\/span><\/span>um flu\u00eddo com carga positiva<\/b><\/span><\/span><\/span> (homog\u00eaneo e quase esf\u00e9rico) <\/b><\/span><\/span><\/span>no qual as passas dispersas sobre o pudim de ameixa s\u00e3o comparados aos el\u00e9trons carregados negativamente imerso em uma gel\u00e9ia de carga positiva.<\/b><\/span><\/span><\/span><\/p>\n

\u00a0Em <\/b><\/span><\/span><\/span>1911,<\/b><\/span><\/span><\/span> depois de <\/b><\/span><\/span><\/span>Thomson, Ernest Rutherford apresentou seu modelo at\u00f4mico com um n\u00facleo densamente composto de carga positiva e rodeado por el\u00e9trons carregados negativamente<\/b><\/span><\/span><\/span>, <\/b><\/span><\/span><\/span>semelhante ao nosso sistema planet\u00e1rio, com o Sol sendo o n\u00facleo.\u00a0\u00a0<\/b><\/span><\/span><\/span>
\nExperimentalmente, <\/b><\/span><\/span><\/span>Rutherford concluiu que o \u00e1tomo era constitu\u00eddo de uma parte central positiva muito pequena, <\/b><\/span><\/span><\/span>mas de <\/b><\/span><\/span><\/span>grande massa que denominou de n\u00facleo <\/b><\/span><\/span><\/span>e uma <\/b><\/span><\/span><\/span>parte envolvente negativa<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>relativamente enorme, a eletrosfera. <\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>dimens\u00e3o do n\u00facleo<\/b><\/span><\/span><\/span> era <\/b><\/span><\/span><\/span>anormalmente pequena em compara\u00e7\u00e3o com o real tamanho do \u00e1tomo.<\/b><\/span><\/span><\/span><\/p>\n

Em <\/b><\/span><\/span><\/span>1913,<\/b><\/span><\/span><\/span> <\/b>Neils Bohr aperfei\u00e7oou o modelo nuclear de Rutherford, <\/b><\/span><\/span><\/span>concluindo que os <\/b><\/span><\/span><\/span>el\u00e9trons estavam presentes em \u00f3rbitas fora do n\u00facleo e que essas \u00f3rbitas eram espec\u00edficas de raio fixo, cada uma caracterizada por n\u00edveis energ\u00e9ticos bem definidos. <\/b><\/span><\/span><\/span>Segundo\u00a0<\/b><\/span><\/span><\/span>Bohr, <\/b><\/span><\/span><\/span>existem <\/b><\/span><\/span><\/span>estados estacion\u00e1rios nos quais os el\u00e9trons possuem \u00f3rbitas est\u00e1veis, <\/b><\/span><\/span><\/span>ou seja, <\/b><\/span><\/span><\/span>podem permanecer nelas\u00a0 indefinidamente, sem perder energia.\u00a0<\/b><\/span><\/span><\/span>Essa <\/b><\/span><\/span><\/span>\u00e9 tanto maior quanto mais longe o el\u00e9tron estiver do n\u00facleo, <\/b><\/span><\/span><\/span>ou seja, <\/b><\/span><\/span><\/span>quanto mais afastada for sua \u00f3rbita. <\/b><\/span><\/span><\/span>\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>presen\u00e7a dessas \u00f3rbitas energ\u00e9ticas, permitiu a Bohr <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>constru\u00e7\u00e3o de um novo modelo at\u00f4mico com as seguintes caracter\u00edsticas:
\n<\/b><\/span><\/span><\/span>\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Caracter\u00edsticas do modelo at\u00f4mico de Bohr<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Cada el\u00e9tron s\u00f3 pode ocupar determinada \u00f3rbita circular <\/b><\/span><\/span><\/span>sempre com a <\/b><\/span><\/span><\/span>mesma energia, <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>permanece indefinidamente, sem irradi\u00e1-la.<\/b><\/span><\/span><\/span><\/p>\n

Essas \u00f3rbitas <\/b><\/span><\/span><\/span>correspondem a <\/b><\/span><\/span><\/span>situa\u00e7\u00f5es est\u00e1veis, denominadas de\u00a0estados estacion\u00e1rios.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

A <\/b><\/span><\/span><\/span>quantidade constante de energia de cada \u00f3rbita \u00e9 tanto maior quanto mais longe o el\u00e9tron estiver do n\u00facleo, ou seja, quanto mais afastada for sua \u00f3rbita.
\n<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0Um <\/b><\/span><\/span><\/span>\u00e1tomo <\/b><\/span><\/span><\/span>armazena<\/b><\/span><\/span><\/span> energia<\/b><\/span><\/span><\/span> quando seus <\/b><\/span><\/span><\/span>el\u00e9trons saltam de uma \u00f3rbita mais interna <\/b><\/span><\/span><\/span>(de menor potencial de energia) <\/b><\/span><\/span><\/span>para uma \u00f3rbita mais externa <\/b><\/span><\/span><\/span>(de maior potencial de energia). <\/b><\/span><\/span><\/span><\/p>\n

Assim, <\/b><\/span><\/span><\/span>sempre que um \u00e1tomo absorve energia, um ou mais de seus el\u00e9trons \u201csaltam\u201d para uma \u00f3rbita mais externa.
\n<\/b><\/span><\/span><\/span>Quando o <\/b><\/span><\/span><\/span>fornecimento<\/b><\/span><\/span><\/span> de <\/b><\/span><\/span><\/span>energia cessa, <\/b><\/span><\/span><\/span>os <\/b><\/span><\/span><\/span>el\u00e9trons que foram deslocados para as \u00f3rbitas mais distantes tendem <\/b><\/span><\/span><\/span>a restaurar o <\/b><\/span><\/span><\/span>equil\u00edbrio retornando \u00e0 sua \u00f3rbita original.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Por\u00e9m, <\/b><\/span><\/span><\/span>toda a\u00e7\u00e3o que acumula energia, se for revertida, ter\u00e1 que liberar essa mesma energia. <\/b><\/span><\/span><\/span><\/p>\n

Ent\u00e3o, quando o <\/b><\/span><\/span><\/span>el\u00e9tron <\/b><\/span><\/span><\/span>retorna \u00e0 \u00f3rbita original<\/b><\/span><\/span><\/span> ele deve <\/b><\/span><\/span><\/span>liberar a mesma quantidade de energia<\/b><\/span><\/span><\/span> recebida e o faz <\/b><\/span><\/span><\/span>sob forma de energia luminosa, ou seja, emitindo um f\u00f3ton.<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>seq\u00fc\u00eancia de figuras abaixo <\/b><\/span><\/span><\/span>ilustra essa situa\u00e7\u00e3o, <\/b><\/span><\/span><\/span>para um \u00e1tomo de hidrog\u00eanio<\/b><\/span><\/span><\/span>. <\/b><\/span><\/span><\/span>Na <\/b><\/span><\/span><\/span>figura I <\/b><\/span><\/span><\/span>voc\u00ea v\u00ea um <\/b><\/span><\/span><\/span>\u00e1tomo em repouso, com<\/b><\/span><\/span><\/span>\"\"<\/p>\n

um el\u00e9tron\u00a0 girando em torno de seu n\u00facleo.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Na <\/b><\/span><\/span><\/span>figura II <\/b><\/span><\/span><\/span>voc\u00ea v\u00ea que um <\/b><\/span><\/span><\/span>f\u00f3ton, proveniente do meio exterior, colidir com esse el\u00e9tron, transferindo-lhe energia, o que faz com que ele salte para uma \u00f3rbita mais externa,<\/b><\/span><\/span><\/span> conforme mostra a <\/b><\/span><\/span><\/span>figura III. <\/b><\/span><\/span><\/span><\/p>\n

Por\u00e9m, em <\/b><\/span><\/span><\/span>sua nova \u00f3rbita, o el\u00e9tron est\u00e1 fora de sua posi\u00e7\u00e3o de equil\u00edbrio. <\/b><\/span><\/span><\/span>E como a <\/b><\/span><\/span><\/span>natureza busca incessantemente o equil\u00edbrio, <\/b><\/span><\/span><\/span>o el\u00e9tron salta novamente para sua \u00f3rbita original, o que faz com que a\u00a0energia seja liberada atrav\u00e9s da emiss\u00e3o de um f\u00f3ton luminoso.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Como a <\/b><\/span><\/span><\/span>energia dos f\u00f3tons s\u00f3 se encontra na natureza em forma de pacotes quantizados <\/b><\/span><\/span><\/span>e de <\/b><\/span><\/span><\/span>valores determinados, fornecidos por E = h.f, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>el\u00e9tron s\u00f3 pode transferir energia para \u00f3rbitas determinadas.<\/b><\/span><\/span><\/span><\/p>\n

Se o <\/b><\/span><\/span><\/span>el\u00e9tron mudar de um estado estacion\u00e1rio para outro, <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>energia diferente <\/b><\/span><\/span><\/span>haver\u00e1 a <\/b><\/span><\/span><\/span>emiss\u00e3o de um f\u00f3ton, <\/b><\/span><\/span><\/span>e sua <\/b><\/span><\/span><\/span>frequ\u00eancia ser\u00e1 dada por f = (E<\/b><\/span><\/span><\/span>inicial<\/b><\/span><\/span><\/sub><\/span>\u00a0– E<\/b><\/span><\/span><\/span>final<\/b><\/span><\/span><\/sub><\/span>)\/h ou (E<\/b><\/span><\/span><\/span>inicial\u00a0<\/b><\/span><\/span><\/sub><\/span>\u2013 E<\/b><\/span><\/span><\/span>final<\/b><\/span><\/span><\/sub><\/span>) = h.f.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"\u00a0<\/span><\/p>\n

As <\/b><\/span><\/span><\/span>\u00f3rbitas do el\u00e9tron s\u00e3o restritas,<\/b><\/span><\/span><\/span> isto \u00e9, <\/b><\/span><\/span><\/span>nem todas as \u00f3rbitas s\u00e3o permitidas em qualquer situa\u00e7\u00e3o. <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>restri\u00e7\u00e3o \u00e9 que o momento angular do el\u00e9tron \u00e9 necessariamente quantizado,<\/b><\/span><\/span><\/span> ou seja, \u00e9 <\/b><\/span><\/span><\/span>um m\u00faltiplo de um valor fundamental.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\u00a0Para <\/b><\/span><\/span><\/span>saber as frequ\u00eancias permitidas<\/b><\/span><\/span><\/span>, na <\/b><\/span><\/span><\/span>equa\u00e7\u00e3o de Bohr <\/b><\/span><\/span><\/span>ser\u00e1 necess\u00e1rio <\/b><\/span><\/span><\/span>conhecer as energias <\/b><\/span><\/span><\/span>dos <\/b><\/span><\/span><\/span>diversos estados estacion\u00e1rios em que um \u00e1tomo de hidrog\u00eanio pode existir. <\/b><\/span><\/span><\/span><\/p>\n

Esse <\/b><\/span><\/span><\/span>c\u00e1lculo<\/b><\/span><\/span><\/span> foi efetuado, pela <\/b><\/span><\/span><\/span>primeira vez, por Bohr baseando-se em um modelo espec\u00edfico do \u00e1tomo de hidrog\u00eanio por ele imaginado.<\/b><\/span><\/span><\/span> <\/b><\/p>\n

O modelo de Bohr teve sucesso apenas no caso do \u00e1tomo de hidrog\u00eanio,<\/b><\/span><\/span><\/span> mas mesmo assim <\/b><\/span><\/span><\/span>influenciou muito o desenvolvimento posterior na F\u00edsica Qu\u00e2ntica.<\/b><\/span><\/span><\/span><\/p>\n

Para o <\/b><\/span><\/span><\/span>\u00e1tomo de hidrog\u00eanio<\/b><\/span><\/span><\/span>(um \u00fanico el\u00e9tron girando em \u00f3rbita circular em torno de um \u00fanico pr\u00f3ton que se encontra no n\u00facleo), a <\/b><\/span><\/span><\/span>equa\u00e7\u00e3o de Bohr, que permite calcular o n\u00edvel energ\u00e9tico de cada \u00f3rbita n, \u00e9 expressa por:<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\u00a0Como <\/b><\/span><\/span><\/span>cada transi\u00e7\u00e3o eletr\u00f4nica <\/b><\/span><\/span><\/span>(salto qu\u00e2ntico, pulo entre dois n\u00edveis de energia) <\/b><\/span><\/span><\/span>\u00e9 quantizada, a energia do f\u00f3ton emitido ou absorvido tamb\u00e9m \u00e9 quantizada e consequentemente o comprimento de onda e a freq\u00fc\u00eancia tamb\u00e9m o s\u00e3o<\/b><\/span><\/span><\/span>. Assim, <\/b><\/span><\/span><\/span>cada frequ\u00eancia de cada f\u00f3ton emitido ou absorvido <\/b><\/span><\/span><\/span>tem uma <\/b><\/span><\/span><\/span>freq\u00fc\u00eancia determinada e fixa para aquele \u00e1tomo <\/b><\/span><\/span><\/span>e para <\/b><\/span><\/span><\/span>aquele salto qu\u00e2ntico.<\/b><\/span><\/span><\/span> Cada <\/b><\/span><\/span><\/span>transi\u00e7\u00e3o eletr\u00f4nica entre \u00e1tomo contribui para a produ\u00e7\u00e3o de uma linha individual no espectro daquele elemento.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\u00a0Observe na <\/b><\/span><\/span><\/span>figura I acima <\/b><\/span><\/span><\/span>que os <\/b><\/span><\/span><\/span>intervalos entre os n\u00edveis de energia n\u00e3o s\u00e3o constantes, <\/b><\/span><\/span><\/span>pois \u00e0 medida que <\/b><\/span><\/span><\/span>aumenta o valor de n, se afastando do n\u00facleo, diminui a varia\u00e7\u00e3o de energia entre dois n\u00edveis energ\u00e9ticos consecutivos.<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>energia <\/b><\/span><\/span><\/span>de cada <\/b><\/span><\/span><\/span>transi\u00e7\u00e3o gen\u00e9rica\u00a0 de n\u00edvel n<\/b><\/span><\/span><\/span>inicial<\/b><\/span><\/span><\/sub><\/span>\u00a0(n<\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/sub><\/span>) a n<\/b><\/span><\/span><\/span>final<\/b><\/span><\/span><\/sub><\/span>\u00a0(n<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/sub><\/span>) \u00e9 fornecida por:\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"\u00a0<\/span><\/p>\n

Para <\/b><\/span><\/span><\/span>calcular o comprimento de onda \u03bb <\/b><\/span><\/span><\/span>(E<\/b><\/span><\/span><\/span>inicial \u2013\u00a0\u00a0<\/b><\/span><\/span><\/sub><\/span>E<\/b><\/span><\/span><\/span>final<\/b><\/span><\/span><\/sub><\/span>)=\u0394E=h.f\u00a0 \"\"\u00a0 c=velocidade da Luz = \u03bb.f\u00a0\"\"\u00a0<\/b><\/span><\/span><\/span><\/p>\n

F = c\/\u03bb\u00a0 \"\"\u00a0\u00a0\u0394E = h.(c\/\u03bb)\u00a0 \"\" \u00a0<\/b><\/span><\/span><\/span>\u03bb \"\"<\/b><\/span><\/span><\/span> <\/b>comprimento de onda do f\u00f3ton emitido ou absorvido.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Outra rela\u00e7\u00e3o matem\u00e1tica\u00a0\"\" <\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>\u0394E = h(c\/\u03bb)\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>\u0394E = mc<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 mc<\/b><\/span><\/span><\/span>2 <\/b><\/span><\/span><\/sup><\/span>= (hc\/\u03bb)\u00a0 \"\"\u00a0 \u00a0<\/b><\/span><\/span><\/span>mc = Q = h\/\u03bb \"\" quantidade de movimento.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Um \u00e1tomo emite um f\u00f3ton luminoso quando <\/b><\/span><\/span><\/span>o el\u00e9tron salta novamente para sua \u00f3rbita original, <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>n\u00edveis de energia mais baixos, <\/b><\/span><\/span><\/span>o que faz com que <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>energia seja liberada<\/b><\/span><\/span><\/span> atrav\u00e9s da emiss\u00e3o de um f\u00f3ton luminoso.\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Fiss\u00e3o Nuclear<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

A\u00a0<\/b><\/span><\/span><\/span>fiss\u00e3o nuclear\u00a0<\/b><\/span><\/span><\/span>consiste\u00a0numa <\/b><\/span><\/span><\/span>rea\u00e7\u00e3o que se inicia com o choque de um n\u00eautron <\/b><\/span><\/span><\/span>com um <\/b><\/span><\/span><\/span>n\u00facleo inst\u00e1vel <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>proporciona a quebra <\/b><\/span><\/span><\/span>deste <\/b><\/span><\/span><\/span>\u00faltimo<\/b><\/span><\/span><\/span> e, por <\/b><\/span><\/span><\/span>este motivo, \u00e9 chamado de fiss\u00e3o nuclear\u00a0(divis\u00e3o do n\u00facleo). <\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Fus\u00e3o Nuclear<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

A <\/b><\/span><\/span><\/span>Fus\u00e3o Nuclear\u00a0 <\/b><\/span><\/span><\/span>\u00e9 o <\/b><\/span><\/span><\/span>processo no qual <\/b><\/span><\/span><\/span>dois ou mais n\u00facleos at\u00f4micos<\/b><\/span><\/span><\/span> se juntam <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>formam um <\/b><\/span><\/span><\/span>outro n\u00facleo de maior n\u00famero<\/b><\/span><\/span><\/span><\/p>\n

At\u00f4mico.<\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>principal tipo de fus\u00e3o que ocorre no interior das estrelas \u00e9 o de Hidrog\u00eanio em H\u00e9lio, <\/b><\/span><\/span><\/span>onde <\/b><\/span><\/span><\/span>dois<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

pr\u00f3tons se fundem em uma part\u00edcula alfa (um n\u00facleo de h\u00e9lio), liberando dois p\u00f3sitrons, dois neutrinos e energia.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Buraco Negro<\/b><\/span><\/span><\/span><\/p>\n

Um\u00a0<\/b><\/span><\/span><\/span>buraco negro\u00a0<\/b><\/span><\/span><\/span>\u00e9 o que <\/b><\/span><\/span><\/span>sobra quando morre uma gigantesca estrela<\/b><\/span><\/span><\/span>, no <\/b><\/span><\/span><\/span>m\u00ednimo 10 vezes maior que o nosso Sol. <\/b><\/span><\/span><\/span><\/p>\n

Uma <\/b><\/span><\/span><\/span>estrela<\/b><\/span><\/span><\/span> \u00e9 um <\/b><\/span><\/span><\/span>imenso e incr\u00edvel reator de fus\u00e3o.<\/b><\/span><\/span><\/span> As <\/b><\/span><\/span><\/span>rea\u00e7\u00f5es de fus\u00e3o<\/b><\/span><\/span><\/span>, que ocorrem no <\/b><\/span><\/span><\/span>n\u00facleo,<\/b><\/span><\/span><\/span> <\/b><\/p>\n

\"\"<\/p>\n

funcionam como <\/b><\/span><\/span><\/span>gigantescas bombas, <\/b><\/span><\/span><\/span>cujas<\/b><\/span><\/span><\/span> explos\u00f5es impedem que a massa da estrela se concentre numa regi\u00e3o pequena. <\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>equil\u00edbrio entre as for\u00e7as oriundas das explos\u00f5es <\/b><\/span><\/span><\/span>e as de <\/b><\/span><\/span><\/span>origem gravitacional define o tamanho da estrela. <\/b><\/span><\/span><\/span><\/p>\n

Quando o <\/b><\/span><\/span><\/span>combust\u00edvel para as rea\u00e7\u00f5es se esgota, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>fus\u00e3o nuclear \u00e9 interrompida.<\/b><\/span><\/span><\/span><\/p>\n

Ao <\/b><\/span><\/span><\/span>mesmo tempo,<\/b><\/span><\/span><\/span> a <\/b><\/span><\/span><\/span>gravidade atrai a mat\u00e9ria para o interior da estrela<\/b><\/span><\/span><\/span>, havendo <\/b><\/span><\/span><\/span>compress\u00e3o<\/b><\/span><\/span><\/span> do <\/b><\/span><\/span><\/span>n\u00facleo,<\/b><\/span><\/span><\/span> que <\/b><\/span><\/span><\/span>se aquece muito. <\/b><\/span><\/span><\/span><\/p>\n

O <\/b><\/span><\/span><\/span>n\u00facleo termina por explodir, arremessando para o espa\u00e7o mat\u00e9ria e radia\u00e7\u00e3o. <\/b><\/span><\/span><\/span><\/p>\n

O que fica \u00e9 o <\/b><\/span><\/span><\/span>n\u00facleo altamente comprimido e extremamente maci\u00e7o. <\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>gravidade em torno dele \u00e9 t\u00e3o forte que nem a luz consegue escapar. Esse objeto literalmente desaparece da vis\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Corpo negro<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

O nome <\/b><\/span><\/span><\/span>“corpo negro” <\/b><\/span><\/span><\/span>foi introduzido por <\/b><\/span><\/span><\/span>Gustav Kirchhoff <\/b><\/span><\/span><\/span>em 1860 e, em <\/b><\/span><\/span><\/span>F\u00edsica, \u00e9 um corpo que absorve toda a radia\u00e7\u00e3o que nele incide n\u00e3o refletindo a luz e nem se deixando atravessar por ela. <\/b><\/span><\/span><\/span><\/p>\n

\u00c9 um absorvedor ideal, sua absorvidade \u00e9 a = 1 e sua refletividade \u00e9 nula r = 0. Como todo bom absorvedor \u00e9 bom e<\/b><\/span><\/span><\/span>missor, ele \u00e9 tamb\u00e9m emissor ideal e sua emissividade \u00e9 e = 1.<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

 <\/p>\n

\"\"<\/p>\n

TEMPERATURAS DE COR NA ESCALA KELVIN<\/b><\/span><\/span><\/span><\/p>\n

O nome acima<\/b><\/span><\/span><\/span> foi criado por um f\u00edsico escoc\u00eas <\/b><\/span><\/span><\/span>no s\u00e9culo 19, <\/b><\/span><\/span><\/span>Lord Kelvin <\/b><\/span><\/span><\/span>com a <\/b><\/span><\/span><\/span>finalidade<\/b><\/span><\/span><\/span> de <\/b><\/span><\/span><\/span>medir <\/b><\/span><\/span><\/span>os <\/b><\/span><\/span><\/span>desvios de propor\u00e7\u00e3o na composi\u00e7\u00e3o da luz branca. <\/b><\/span><\/span><\/span><\/p>\n

Para isso, ele imaginou um <\/b><\/span><\/span><\/span>hipot\u00e9tico objeto totalmente negro chamado por ele de ‘corpo negro\u2019, <\/b><\/span><\/span><\/span>porque <\/b><\/span><\/span><\/span>absorveria 100% de qualquer luz que incidisse sobre <\/b><\/span><\/span><\/span>ele que, ao <\/b><\/span><\/span><\/span>ser aquecido, passaria a emitir luz, pois todo bom absorvedor \u00e9 tamb\u00e9m bom emissor. <\/b><\/span><\/span><\/span><\/p>\n

E, al\u00e9m disso, a <\/b><\/span><\/span><\/span>luz emitida por esse \u201ccorpo negro\u201d <\/b><\/span><\/span><\/span>iria mudando <\/b><\/span><\/span><\/span>gradualmente de cor.<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>analogia f<\/b><\/span><\/span><\/span>oi feita com um <\/b><\/span><\/span><\/span>peda\u00e7o de metal (te\u00f3rico corpo negro) que ao ser aquecido mudava de<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

cor come\u00e7ando com o vermelho e passando pelo amarelo, pelo branco e pelo branco azulado, conforme voc\u00ea pode observar na escala de temperatura de cor acima.<\/b><\/span><\/span><\/span>,A \u00e0 qual deu seu nome e<\/b><\/span><\/span><\/span><\/p>\n

Quando um <\/b><\/span><\/span><\/span>corpo negro \u00e9 aquecido, <\/b><\/span><\/span><\/span>ele se\u00a0 torna uma <\/b><\/span><\/span><\/span>fonte ideal de radia\u00e7\u00e3o t\u00e9rmica e de radia\u00e7\u00e3o eletromagn\u00e9tica.
\n<\/b><\/span><\/span><\/span>Um <\/b><\/span><\/span><\/span>corpo negro <\/b><\/span><\/span><\/span>a uma <\/b><\/span><\/span><\/span>temperatura T emite <\/b><\/span><\/span><\/span>exatamente os <\/b><\/span><\/span><\/span>mesmos comprimentos de onda e intensidades que estariam presentes num ambiente em equil\u00edbrio t\u00e9rmico em T.<\/b><\/span><\/span><\/span><\/p>\n

Como a <\/b><\/span><\/span><\/span>radia\u00e7\u00e3o em tal ambiente possuiria um espectro dependente apenas de sua temperatura, <\/b><\/span><\/span><\/span>a <\/b><\/span><\/span><\/span>temperatura do objeto est\u00e1 diretamente associada aos comprimentos de onda que emite. <\/b><\/span><\/span><\/span><\/p>\n

Em <\/b><\/span><\/span><\/span>temperatura ambiente,<\/b><\/span><\/span><\/span> corpos negros emitem <\/b><\/span><\/span><\/span>infravermelho,<\/b><\/span><\/span><\/span> <\/b>mas <\/b><\/span><\/span><\/span>\u00e0 medida que a temperatura aumenta algumas centenas de graus Celsius, corpos negros come\u00e7am a emitir radia\u00e7\u00e3o em comprimentos de onda vis\u00edveis: come\u00e7ando no vermelho, passando por amarelo, branco e finalmente acabando no azul, ap\u00f3s o qual a emiss\u00e3o passa a incluir crescentes quantidades de ultravioleta.
\n<\/b><\/span><\/span><\/span>A <\/b><\/span><\/span><\/span>radia\u00e7\u00e3o emitida por um corpo negro <\/b><\/span><\/span><\/span>mostrou uma falha na <\/b><\/span><\/span><\/span>teoria cl\u00e1ssica, <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>explicava<\/b><\/span><\/span><\/span> as <\/b><\/span><\/span><\/span>emiss\u00f5es satisfatoriamente apenas em baixas temperaturas. <\/b><\/span><\/span><\/span><\/p>\n

O estudo das <\/b><\/span><\/span><\/span>leis de corpos negros levou ao surgimento da mec\u00e2nica qu\u00e2ntica.<\/b><\/span><\/span><\/span><\/p>\n

stabeleceu que \u00e0 temperatura de 1.200 K (graus Kelvin) o corpo negro tornaria vermelho. E q<\/b><\/span><\/span><\/span><\/p>\n

\"\"quanto mais aquecido, mais sua tonalidade se alterava, correspondendo a temperaturas intee<\/b><\/span><\/span><\/span> <\/b><\/p>\n

Varia\u00e7\u00e3o a intensidade da radia\u00e7\u00e3o emitida por um corpo negro em fun\u00e7\u00e3o do comprimento de onda para algumas temperaturas.<\/b><\/span><\/span><\/span><\/p>\n

e temperatura. A escala Kelvin, Assal\u00e9m de utilizada na representa\u00e7\u00e3o de cores, \u00e9 uma das escalas utilizadas para medir quaisquer temperaturas. Nesta escala, o valor zero \u00e9 associado \u00e0 <\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>figura abaixo <\/b><\/span><\/span><\/span>mostra <\/b><\/span><\/span><\/span>como varia a intensidade da radia\u00e7\u00e3o emitida por um corpo negro em fun\u00e7\u00e3odo comprimento de onda para algumas temperaturas<\/b><\/span><\/span><\/span> temperaturas. <\/b><\/span><\/span><\/span>correspondente ao c\"\"hamado “zero absoluto”. Esta temperatura corresponde a -273,3 graus na escala Celsius de tO que voc\u00ea deve saber, <\/b><\/span><\/span><\/span>O que voc\u00ea deve saber, informa\u00e7\u00f5es e dicas<\/b><\/span><\/span><\/span><\/p>\n

\"\"r<\/b><\/span><\/span><\/span> <\/b>O modelo at\u00f4mico de Bohr tem as seguintes caracter\u00edsticas:<\/b><\/span><\/span><\/span> <\/b><\/p>\n

\"\" Cada el\u00e9tron s\u00f3 <\/b><\/span><\/span><\/span>pode ocupar <\/b><\/span><\/span><\/span>determinada \u00f3rbita circular <\/b><\/span><\/span><\/span>sempre com a <\/b><\/span><\/span><\/span>mesma energia, <\/b><\/span><\/span><\/span>que <\/b><\/span><\/span><\/span>permanece indefinidamente, sem irradi\u00e1-la. <\/b><\/span><\/span><\/span><\/p>\n

Essas <\/b><\/span><\/span><\/span>\u00f3rbitas <\/b><\/span><\/span><\/span>correspondem a <\/b><\/span><\/span><\/span>situa\u00e7\u00f5es est\u00e1veis, <\/b><\/span><\/span><\/span>denominadas de\u00a0<\/b><\/span><\/span><\/span>estados estacion\u00e1rios. <\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>quantidade constante de energia de cada \u00f3rbita \u00e9 tanto maior quanto mais longe o el\u00e9tron estiver do n\u00facleo, ou seja, quanto mais afastada for sua \u00f3rbita.\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0Um <\/b><\/span><\/span><\/span>\u00e1tomo armazena energia <\/b><\/span><\/span><\/span>fazendo <\/b><\/span><\/span><\/span>seus el\u00e9trons saltarem de uma \u00f3rbita mais interna <\/b><\/span><\/span><\/span>(de menor potencial de energia) <\/b><\/span><\/span><\/span>para uma \u00f3rbita mais externa <\/b><\/span><\/span><\/span>(de maior potencial de energia). <\/b><\/span><\/span><\/span><\/p>\n

Assim, <\/b><\/span><\/span><\/span>sempre que um \u00e1tomo absorve energia, um ou mais de seus el\u00e9trons \u201csaltam\u201d para uma \u00f3rbita mais externa.
\n<\/b><\/span><\/span><\/span>Quando o <\/b><\/span><\/span><\/span>fornecimento de energia cessa,<\/b><\/span><\/span><\/span> os <\/b><\/span><\/span><\/span>el\u00e9trons que foram deslocados para as \u00f3rbitas mais distantes<\/b><\/span><\/span><\/span> tendem a <\/b><\/span><\/span><\/span>restaurar o equil\u00edbrio retornando \u00e0 sua \u00f3rbita original. <\/b><\/span><\/span><\/span><\/p>\n

Por\u00e9m, <\/b><\/span><\/span><\/span>toda a\u00e7\u00e3o que acumula energia, se for revertida, ter\u00e1 que liberar essa mesma energia. <\/b><\/span><\/span><\/span><\/p>\n

Ent\u00e3o, quando o <\/b><\/span><\/span><\/span>el\u00e9tron retorna \u00e0 \u00f3rbita original <\/b><\/span><\/span><\/span>ele deve <\/b><\/span><\/span><\/span>liberar a mesma quantidade de energia recebida e o faz sob forma de energia luminosa, ou seja, emitindo um f\u00f3ton.<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"\u00a0<\/span>A energia de cada transi\u00e7\u00e3o gen\u00e9rica\u00a0 de n\u00edvel n<\/b><\/span><\/span><\/span>inicial<\/b><\/span><\/span><\/sub><\/span>\u00a0(n<\/b><\/span><\/span><\/span>i<\/b><\/span><\/span><\/sub><\/span>) a n<\/b><\/span><\/span><\/span>final<\/b><\/span><\/span><\/sub><\/span>\u00a0(n<\/b><\/span><\/span><\/span>f<\/b><\/span><\/span><\/sub><\/span>) \u00e9 fornecida por:\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"\u00a0<\/span>(E<\/b><\/span><\/span><\/span>inicial \u2013\u00a0\u00a0<\/b><\/span><\/span><\/sub><\/span>E<\/b><\/span><\/span><\/span>final<\/b><\/span><\/span><\/sub><\/span>) = \u0394E = h.f\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 c = velocidade da luz=\u03bb.f\u00a0 \"\"\u00a0 f = c\/\u03bb\u00a0 \"\"\u00a0\u00a0<\/b><\/span><\/span><\/span>\u0394E = h.(c\/\u03bb)\u00a0 \"\"\u00a0 \u03bb (comprimento de onda do f\u00f3ton emitido ou absorvido).<\/b><\/span><\/span><\/span><\/p>\n

\"\"\u00a0<\/span>Outra rela\u00e7\u00e3o matem\u00e1tica\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>\u0394E=h.(c\/\u03bb)\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 \u0394E=mc<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span> \"\"\u00a0 mc<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sup><\/span>=hc\/\u03bb\u00a0 \"\"\u00a0\u00a0<\/b><\/span><\/span><\/span>mc = h\/\u03bb = Q ( quantidade de movimento).<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Radiografias<\/span><\/span><\/span><\/p>\n

Os <\/b><\/span><\/span><\/span>raios X, <\/b><\/span><\/span><\/span>descobertos em 1895 pelo f\u00edsico <\/b><\/span><\/span><\/span>alem\u00e3o Wilhelm Rontgen<\/b><\/span><\/span><\/span>, s\u00e3o produzidos quando <\/b><\/span><\/span><\/span>el\u00e9trons s\u00e3o desacelerados ao atingirem um alvo met\u00e1lico de alto ponto de fus\u00e3o como, por exemplo, o Tungst\u00eanio. <\/b><\/span><\/span><\/span>Essa <\/b><\/span><\/span><\/span>desacelera\u00e7\u00e3o produz ondas eletromagn\u00e9ticas de alta freq\u00fc\u00eancia denominadas de Raios X, que atravessam a maioria dos materiais conhecidos e impressionam chapas fotogr\u00e1ficas<\/b><\/span><\/span><\/span>. <\/b><\/span><\/span><\/span>\"\"<\/p>\n

A <\/b><\/span><\/span><\/span>imagem do corpo <\/b><\/span><\/span><\/span>de uma pessoa em uma <\/b><\/span><\/span><\/span>chapa de Raios X <\/b><\/span><\/span><\/span>representa um processo em que <\/b><\/span><\/span><\/span>parte da radia\u00e7\u00e3o \u00e9 absorvida pelo corpo, <\/b><\/span><\/span><\/span>e os <\/b><\/span><\/span><\/span>claros e escuros da imagem representam, respectivamente, os tecidos mais e menos absorvedores de radia\u00e7\u00e3o.<\/b><\/span><\/span><\/span><\/p>\n

Assim, nas <\/b><\/span><\/span><\/span>radiografias os \u00a0ossos saem brancos<\/b><\/span><\/span><\/span> e <\/b><\/span><\/span><\/span>tecidos em volta negros<\/b><\/span><\/span><\/span>\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 isso ocorre porque <\/b><\/span><\/span><\/span>o osso, cuja estrutura \u00e9 mais densa que a do tecido mole, absorve mais radia\u00e7\u00e3o ficando com apar\u00eancia clara <\/b><\/span><\/span><\/span>enquanto que o <\/b><\/span><\/span><\/span>tecido mole, menos denso, \u00e9 atravessado pelos raios X, ficando com apar\u00eancia mais escura.<\/b><\/span><\/span><\/span><\/p>\n

\"\" \u00a0Voc\u00ea deve <\/b><\/span><\/span><\/span>conhecer e entender <\/b><\/span><\/span><\/span>os <\/b><\/span><\/span><\/span>conceitos<\/b><\/span><\/span><\/span> de <\/b><\/span><\/span><\/span>corpo negro, buraco negro, fus\u00e3o e fiss\u00e3o nuclear fornecidos acima.<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

\"\"<\/p>\n

Alguns exerc\u00edcios interessantes que seria conveniente para voc\u00ea conferir as resolu\u00e7\u00f5es:<\/b><\/span><\/span><\/span><\/p>\n

01-(UFJF-MG)<\/b><\/span><\/span><\/span> \"\"<\/b><\/span><\/span><\/span><\/p>\n

Resolu\u00e7\u00e3o:<\/b><\/span><\/span><\/span><\/p>\n

Observe que <\/b><\/span><\/span><\/span>para saltar do n\u00edvel 1 (n<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>) para o n\u00edvel zero (n<\/b><\/span><\/span><\/span>\u221e<\/b><\/span><\/span><\/sub><\/span>), <\/b><\/span><\/span><\/span>onde o <\/b><\/span><\/span><\/span>el\u00e9tron se ioniza, <\/b><\/span><\/span><\/span>foram <\/b><\/span><\/span><\/span>gastos (E<\/b><\/span><\/span><\/span>1<\/b><\/span><\/span><\/sub><\/span>\u00a0– E<\/b><\/span><\/span><\/span>\u221e<\/b><\/span><\/span><\/sub><\/span>) = \u2502-13,6 – 0\u2502= 13,6 eV\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 como <\/b><\/span><\/span><\/span>recebeu 20 eV e gastou 16,3 eV,<\/b><\/span><\/span><\/span> v\u00e3o sobrar\u00a0 \"\"\u00a0 20,0 \u2013 13,6 = <\/b><\/span><\/span><\/span>6,4 eV<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

R- C<\/b><\/span><\/span><\/span><\/p>\n

\"\"<\/p>\n

Resolu\u00e7\u00e3o:<\/b><\/span><\/span><\/span><\/p>\n

Lembre-se de que a <\/b><\/span><\/span><\/span>velocidade de todas as cores e de todas as radia\u00e7\u00f5es eletromagn\u00e9ticas \u00e9 sempre a mesma no v\u00e1cuo <\/b><\/span><\/span><\/span>e, aproximadamente no ar <\/b><\/span><\/span><\/span>(3,0.10<\/b><\/span><\/span><\/span>8<\/b><\/span><\/span><\/sup><\/span>m\/s)\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0\u00a0 <\/b><\/span><\/span><\/span>cada cor tem velocidades diferentes <\/b><\/span><\/span><\/span>em <\/b><\/span><\/span><\/span>outros meios homog\u00eaneos e transparentes (vidro, \u00e1gua, etc.).<\/b><\/span><\/span><\/span><\/p>\n

A <\/b><\/span><\/span><\/span>energia de cada cor \u00e9 diretamente proporcional \u00e0 freq\u00fc\u00eancia (f) <\/b><\/span><\/span><\/span>e <\/b><\/span><\/span><\/span>inversamente proporcional ao comprimento de onda (\u03bb), pois \u0394E = h.(c\/\u03bb) = h.f\u00a0\u00a0\"\"<\/b><\/span><\/span><\/span>\u00a0 da <\/b><\/span><\/span><\/span>tabela, o menor \u03bb, a mais energ\u00e9tica \u00e9 a violeta.<\/b><\/span><\/span><\/span><\/p>\n

R- C<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

03-(UFC-CE)<\/b><\/span><\/span><\/span> <\/b>Na <\/b><\/span><\/span><\/span>figura,<\/b><\/span><\/span><\/span> as flechas numeradas <\/b><\/span><\/span><\/span>de 1 at\u00e9 9 representam transi\u00e7\u00f5es poss\u00edveis <\/b><\/span><\/span><\/span>de <\/b><\/span><\/span><\/span>ocorrer entre alguns n\u00edveis de energia do \u00e1tomo de hidrog\u00eanio de acordo com o modelo de Bohr.<\/b><\/span><\/span><\/span><\/p>\n

Para <\/b><\/span><\/span><\/span>ocorrer a transi\u00e7\u00e3o, <\/b><\/span><\/span><\/span>o <\/b><\/span><\/span><\/span>\u00e1tomo emite <\/b><\/span><\/span><\/span>(ou absorve) <\/b><\/span><\/span><\/span>um f\u00f3ton cuja energia \u2502\u0394E\u2502= h(c\/\u03bb), onde (h \u00e9 a constante de Planck, \u03bb \u00e9 o comprimento de onda do f\u00f3ton e \u0394E \u00e9 a diferen\u00e7a de energia entre os dois n\u00edveis envolvidos na transi\u00e7\u00e3o).<\/b><\/span><\/span><\/span>\"\"<\/p>\n

Suponha que o <\/b><\/span><\/span><\/span>\u00e1tomo emite os f\u00f3tons X e Y, cujos comprimentos de onda s\u00e3o, respectivamente, \u03bb<\/b><\/span><\/span><\/span>x <\/b><\/span><\/span><\/sub><\/span>= 1,03.10<\/b><\/span><\/span><\/span>-7<\/b><\/span><\/span><\/sup><\/span>\u00a0m e \u03bb<\/b><\/span><\/span><\/span>y <\/b><\/span><\/span><\/sub><\/span>= 4,85.<\/b><\/span><\/span><\/span><\/p>\n

10<\/b><\/span><\/span><\/span>-7<\/b><\/span><\/span><\/sup><\/span>m.<\/b><\/span><\/span><\/span><\/p>\n

As <\/b><\/span><\/span><\/span>transi\u00e7\u00f5es corretamente associadas \u00e0s emiss\u00f5es desses dois f\u00f3tons s\u00e3o (use h = 4,13.10<\/b><\/span><\/span><\/span>-15 <\/b><\/span><\/span><\/sup><\/span>eV.s e c = 3,0.10<\/b><\/span><\/span><\/span>8 <\/b><\/span><\/span><\/sup><\/span>m\/s).<\/b><\/span><\/span><\/span><\/p>\n

a) <\/b><\/span><\/span><\/span>4 e 8\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

b) <\/b><\/span><\/span><\/span>2 e 6\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

c) <\/b><\/span><\/span><\/span>3 e 9 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

d) <\/b><\/span><\/span><\/span>5 e 7\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/b><\/span><\/span><\/span><\/p>\n

e) <\/b><\/span><\/span><\/span>1 e 7\u00a0<\/b><\/span><\/span><\/span><\/p>\n

Resolu\u00e7\u00e3o:\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span>\u2502\u0394E\u2502<\/b><\/span><\/span><\/span>x <\/b><\/span><\/span><\/sub><\/span>= h(c\/\u03bb) <\/b><\/span><\/span><\/span>= 4,13.10<\/b><\/span><\/span><\/span>-15<\/b><\/span><\/span><\/sup><\/span>.(3.10<\/b><\/span><\/span><\/span>8<\/b><\/span><\/span><\/sup><\/span>\/1,03.10<\/b><\/span><\/span><\/span>-7<\/b><\/span><\/span><\/sup><\/span>) \"\"<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>\u2502\u0394E\u2502<\/b><\/span><\/span><\/span>x <\/b><\/span><\/span><\/sub><\/span>= 12,03 eV.<\/b><\/span><\/span><\/span><\/p>\n

\u00a0\u2502\u0394E\u2502<\/b><\/span><\/span><\/span>y<\/b><\/span><\/span><\/sub><\/span>= h(c\/\u03bb) <\/b><\/span><\/span><\/span>= 4,13.10<\/b><\/span><\/span><\/span>-15<\/b><\/span><\/span><\/sup><\/span>. (3.10<\/b><\/span><\/span><\/span>8<\/b><\/span><\/span><\/sup><\/span>\/4,85.10<\/b><\/span><\/span><\/span>-7<\/b><\/span><\/span><\/sup><\/span>)\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>\u2502\u0394E\u2502<\/b><\/span><\/span><\/span>y <\/b><\/span><\/span><\/sub><\/span>= 2,55 eV.<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span>Os <\/b><\/span><\/span><\/span>valores mais pr\u00f3ximos s\u00e3o de 2 e 6\u00a0 \"\"<\/b><\/span><\/span><\/span>\u00a0 <\/b><\/span><\/span><\/span>\u2502\u0394E<\/b><\/span><\/span><\/span>2<\/b><\/span><\/span><\/sub><\/span>\u2502<\/b><\/span><\/span><\/span> <\/b>= 13,6 \u2013 1,51 <\/b><\/span><\/span><\/span>= 12,09 eV\u00a0 \"\" \u2502\u0394E<\/b><\/span><\/span><\/span>6<\/b><\/span><\/span><\/sub><\/span>\u2502<\/b><\/span><\/span><\/span> <\/b>= 3,40 \u2013 0,85 <\/b><\/span><\/span><\/span>= 2,55 eV.<\/b><\/span><\/span><\/span><\/p>\n

R- B<\/b><\/span><\/span><\/span><\/p>\n

\u00a0<\/span><\/p>\n

\"\"<\/p>\n

Se voc\u00ea quiser se aprofundar e dominar melhor o assunto eu separei algunas exerc\u00edcios para que voc\u00ea possa analisar as resolu\u00e7\u00f5es. S\u00e3o os exerc\u00edcios de n\u00fameros 02, 04, 08, 09, 11, 12, 14, 16, 18, 20, 25, 29 e 39.<\/b><\/span><\/span><\/span><\/p>\n

 <\/p>\n

Confira os exerc\u00edcios propostos<\/span><\/a><\/h3>\n","protected":false},"excerpt":{"rendered":"

Estrutura At\u00f4mica \u2013 \u00c1tomo de Bohr Breve hist\u00f3rico da descoberta do \u00e1tomo A partir dos anos 1600 do s\u00e9culo atual, a busca do \u00e1tomo se tornou um exerc\u00edcio experimental para diversos cientistas not\u00e1veis\u00a0entre eles est\u00e3o Robert Boyle, John Dalton, JJ Thomson, Ernest Rutherford e Niels Bohr. Boyle realizou experimentos com raios cat\u00f3dicos (final do s\u00e9culo XIX) cuja consequ\u00eancia foi a<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":125,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-2487","page","type-page","status-publish","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2487","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/comments?post=2487"}],"version-history":[{"count":2,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2487\/revisions"}],"predecessor-version":[{"id":2496,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/2487\/revisions\/2496"}],"up":[{"embeddable":true,"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/pages\/125"}],"wp:attachment":[{"href":"https:\/\/fisicaevestibular.com.br\/novo\/wp-json\/wp\/v2\/media?parent=2487"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}