Electron Configuration

Draw Bohr, electron configuration notation and energy level diagrams for sulfur and vanadium

Sulfur 1s2 2s2 2p6 3s2 3p4 +16 3 2 1 s px py pz

Vanadium 1s2 2s2 2p6 3s2 3p6 4s2 3d3 4 3 2 1 s px py pz d1 d2 d3 d4 d5 +23 1s2 2s2 2p6 3s2 3p6 4s2 3d3 4 3 2 1 s px py pz d1 d2 d3 d4 d5

Electron Configurations: the ways in which electrons are Electron Configurations: the ways in which electrons are arranged around the nuclei of atoms. Three Rules: 1. The Aufbau Principle - Electrons enter the lowest energy orbital of the lowest energy shell first. Seventh energy level 7s 7p Sixth energy level 6s 6p 6d Fifth energy level 5s 5p 5d 5f Fourth energy level 4s 4p 4d 4f Third energy level 3s 3p 3d Second energy level 2s 2p First energy level 1s The sequence: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10

Electron Configurations: the ways in which electrons are Electron Configurations: the ways in which electrons are arranged around the nuclei of atoms. Three Rules: 2. The Pauli Exclusion Principle – No electron pairing takes place in the p, d, or f orbitals until each orbital contains one electron of the given set. 3. Hund’s Rule – Nor orbital can contain more than two electrons at any given time.

Exceptions 1. Under normal circumstances an atom will exist at ground state having the electrons orbiting on shells as previously described. By giving an atom energy, it could become excited at which point one or more electrons my jump to a higher energy level. Ground state sodium: 1s2 2s2 2p6 3s1 Excited sodium: 1s2 2s2 2p6 4s1 After excitation the atom may return to a lower excited state, or the ground state, by emitting a photon with a characteristic amount of energy.

Exceptions 2. A half full “s” orbital and a full “d” sub shell (5 e-) or “d” shell (10e-) is more stable than 4 or 9 electrons in a “d” sub shell or shell. What you would expect for Cr 1s2 2s2 2p6 3s2 3p6 4s2 3d4 4 3 2 1 s px py pz d1 d2 d3 d4 d5

Exceptions A half full “s” orbital and a full “d” sub shell (5 e-) or “d” shell (10e-) is more stable than 4 or 9 electrons in a “d” sub shell or shell. What you actually find for Cr 1s2 2s2 2p6 3s2 3p6 4s1 3d5 4 3 2 1 s px py pz d1 d2 d3 d4 d5

Exceptions A half full “s” orbital and a full “d” sub shell (5 e-) or “d” shell (10e-) is more stable than 4 or 9 electrons in a “d” sub shell or shell. What you would expect for Cu 1s2 2s2 2p6 3s2 3p6 4s2 3d9 4 3 2 1 s px py pz d1 d2 d3 d4 d5

Exceptions A half full “s” orbital and a full “d” sub shell (5 e-) or “d” shell (10e-) is more stable than 4 or 9 electrons in a “d” sub shell or shell. What you actually find for Cu 1s2 2s2 2p6 3s2 3p6 4s1 3d10 4 3 2 1 s px py pz d1 d2 d3 d4 d5

Exceptions A half full “s” orbital and a full “d” sub shell (5 e-) or “d” shell (10e-) is more stable than 4 or 9 electrons in a “d” sub shell or shell. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d9 What you would expect for Au 6 5 4 3 2 1 s px py pz d1 d2 d3 d4 d5

Exceptions A half full “s” orbital and a full “d” sub shell (5 e-) or “d” shell (10e-) is more stable than 4 or 9 electrons in a “d” sub shell or shell. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s1 4f14 5d10 What you actually find for Au 6 5 4 3 2 1 s px py pz d1 d2 d3 d4 d5

Principal Quantum Number Quantum numbers (n) identify the energy possessed by an electron in any orbital under study. N = 1, 2, 3, etc. Eenrgy Level Types of Orbitals Actual Orbitals Max # of Electrons n

Principal Quantum Number Quantum numbers (n) identify the energy possessed by an electron in any orbital under study. N = 1, 2, 3, etc. Eenrgy Level Types of Orbitals Actual Orbitals Max # of Electrons n 1 1 – s 2

Principal Quantum Number Quantum numbers (n) identify the energy possessed by an electron in any orbital under study. N = 1, 2, 3, etc. Eenrgy Level Types of Orbitals Actual Orbitals Max # of Electrons n 1 1 – s 2 2 – s, p 4 – s, px, py, pz 8

Principal Quantum Number Eenrgy Level Types of Orbitals Actual Orbitals Max # of Electrons n 1 1 – s 2 2 – s, p 4 – s, px, py, pz 8 3 4

Principal Quantum Number Eenrgy Level Types of Orbitals Actual Orbitals Max # of Electrons n 1 1 – s 2 2 – s, p 4 – s, px, py, pz 8 3 3 – s, p, d 9 – s, px, py, pz, dz2, dxy, dxz, dyz, dx2 – y2 18 4

Principal Quantum Number Eenrgy Level Types of Orbitals Actual Orbitals Max # of Electrons n 1 1 – s 2 2 – s, p 4 – s, px, py, pz 8 3 3 – s, p, d 9 – s, px, py, pz, dz2, dxy, dxz, dyz, dx2 – y2 18 4 4 – s, p, d, f 16 – s, px, py, pz, dz2, dxy, dxz, dyz, dx2 – y2, fz3, fxz2, fyz2, fxy2, fx(x2-2), fz(x2-2), fy(3y2-2) 32

Principal Quantum Number Eenrgy Level Types of Orbitals Actual Orbitals Max # of Electrons n n2 2n2 1 1 – s 2 2 – s, p 4 – s, px, py, pz 8 3 3 – s, p, d 9 – s, px, py, pz, dz2, dxy, dxz, dyz, dx2 – y2 18 4 4 – s, p, d, f 16 – s, px, py, pz, dz2, dxy, dxz, dyz, dx2 – y2, fz3, fxz2, fyz2, fxy2, fx(x2-2), fz(x2-2), fy(3y2-2) 32

Some Questions to try: 1. What is the quantum number for the valence electrons of Mg, Te and Zr? 2. Give Bohr diagrams, energy level diagrams and electron configuration notation for each of the following atoms: C, S, Kr and Zr. 3. Consider the following two neutral atoms. A. 1s2 2s2 2p6 3s2 3p4 B. 1s2 2s2 2p6 3s2 3p3 5s1 Which of the following statements are false? a) B is an element at ground state. b) Eenrgy is required to change A to B c) A & B are two different atoms d) Less energy is required to remove an electron from B than from A. 4. For n=6, a) how many electrons can this energy level hold? b) How many types of orbitals does this level have? c) How many actual orbitals can this level hold?