Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Bohr’s Atomic Model Bohr’s Atomic Model • In 1913, Neils Bohr, a Dane, proposed his model of the atom. It was a modification of the Rutherford model. Bohr however put the electrons in certain circular orbits called shells or principal energy levels (PEL’s). 1st shell (2 electrons max.) Nucleus Empty space + 2nd shell (8 electrons max.) 3rd shell (18 electrons max.) The “planetary” model Bohr’s Atomic Model • Protons and neutrons are found in the nucleus. • Electrons orbit the nucleus in various shells. • Everything else is empty space. 1st shell (2 electrons max.) Nucleus Empty space + 2nd shell (8 electrons max.) 3rd shell (18 electrons max.) The “planetary” model Bohr’s Atomic Model Q:What are the Bohr models for the neutral atoms of the three isotopes of hydrogen? A: Step-1 Draw a box to represent the nucleus. Step-2 Determine the number of protons and neutrons and place them in the nucleus. Step-3 Draw one circle around the nucleus to represent the electron shell and then place the one electron in the shell. 1p 0n H-1 e- 1p 1n H-2 e- 1p 2n H-3 e- Bohr’s Atomic Model Q:What are the Bohr models for the neutral atoms of the two isotopes of carbon? A: Step-1 Draw a box to represent the nucleus. Step-2 Determine the number of protons and neutrons and place them in the nucleus. Step-3 Draw two circles around the nucleus to represent the electron shells and then place the six electron in the shells as indicated by the electron configuration. ee- e6p 6n e- e- e- C-12 ee- e6p 8n e- ee- C-14 Bohr’s Atomic Model Q:What are the Bohr models for the neutral atom 27Al and the ion 23Na1+ ? A: Step-1 Draw a box to represent the nucleus. Step-2 Determine the number of protons and neutrons and place them in the nucleus. Step-3 As indicated by the electron configuration, draw arcs to represent the electron shells and place the electron on them. 13p 14n 27Al 2e- 8e- 3e- 11p 12n 23Na1+ 2e- 8e- 0e- Bohr’s Atomic Model Q:What are the Bohr models for the ion 37Cl1- and the neutral atom of calcium-42? A: Step-1 Draw a box to represent the nucleus. Step-2 Determine the number of protons and neutrons and place them in the nucleus. Step-3 As indicated by the electron configuration, draw arcs to represent the electron shells and place the electron on them. 17p 20n 37Cl1- 2e- 8e- 8e- 20p 22n 2e- 8e- Calcium-42 8e- 2e- Bohr’s Atomic Model • The last shell holding electrons is called the valence. • Electrons in the last shell are called valence electrons. Q: How many valence electron are there in 37Cl1-? A: 8 Q: Which shell in a neutral atom of calcium-42 is the valence? A: 4th 17p 20n 37Cl1- 2e- 8e- 8e- 20p 22n 2e- 8e- Calcium-42 8e- 2e-