Electronic Configuration according to Quantum Mechanics The location of an electron is described by 3 terms. 1st Term: Shell (n) n = 3 n = 2 lone electron of Hydrogen n = 1

n = 3 2nd Term: subshell - designated by s, p,d,f n = 2 1s The first shell (1) has one subshell (s).

2nd Term: subshell - designated by s, p,d,f - refers to the shape(s) of the area in which the electron can be located. - also designates an energy level within the shell. n = 3 n = 2 1s The first shell (1) has one subshell (s). The s subshell is spherical in shape and has 1 orbital 3rd Term: orbital

2nd Term: subshell - designated by s, p,d,f - refers to the shape(s) of the area in which the electron can be located. - also designates an energy level within the shell. n = 3 n = 2 1s The first shell (1) has one subshell (s). The s subshell is spherical in shape and has 1 orbital 3rd Term: orbital Each orbital can accommodate 2 electrons

The Electronic Configuration of Hydrogen energy The first shell (1) has one subshell (s). The s subshell is spherical in shape and has 1 orbital Electronic configuration H 1s1 1s shell # of electrons present subshell H 1s  Orbital Energy Level Diagram

The Electronic Configuration of Helium He: Atomic # of 2, 2 electrons in a neutral He atom 1s

The Electronic Configuration of Helium He: Atomic # of 2, 2 electrons in a neutral He atom H 1s1 He 1s2 He 1s  1s **if there are 2 electrons in the same orbital they must have the opposite spin. (Pauli’s Exclusion Principle)

The Electronic Configuration of Lithium (Li) Li: Z=3 Li has 3 electrons. 2nd shell (2) 1s

The Electronic Configuration of Lithium (Li) Li: Z=3 Li has 3 electrons. - The 2nd shell (n= 2) has 2 subshells which are s and p. 2p 2s 2nd shell 1s

The Electronic Configuration of Lithium (Li) Li: Z=3 Li has 3 electrons. 2p 2s 2nd shell 1s 2s  Li 1s  Li 1s22s1 Electronic configuration Orbital Energy Level Diagram

The Electronic Configuration of Berylium (Be) Be: Z=4 Be has 4 electrons. 2p 2s 2nd shell 1s 2s  Be 1s   Be 1s22s2 Electronic configuration Orbital Energy Level Diagram

- refers to the shape(s) of the area in which the electron subshell - designated by s, p,d,f - refers to the shape(s) of the area in which the electron can be located. - also designates an energy level within the shell. - relative energy: s < p < d < f s subshell: spherical 1 orbital p subshell: pair of lobes z x y x y z

Our Orbital Picture of Be The first shell (1s) is filled. The 2s orbital has 2 e- present. The 2p orbitals are empty. The 2p orbitals have room for 6 e-

The Electronic Configuration of Boron (B) B: Z=5 B has 5 electrons. 2p 2p 2s 2s 2nd shell 2nd shell 1s 1s Be 1s22s2 B 1s22s22p1 2p  2s  B 1s  2s  Be 1s 

The Electronic Configuration of Carbon (C) C: Z=6 C has 6 electrons. 2p 2p 2s 2s 2nd shell 2nd shell 1s 1s B 1s22s22p1 C 1s22s22px1py1 2p  2s  B 1s  2p   2s  C 1s 

Our Orbital Picture of C The first shell (1s) is filled. The 2s orbital has 2 e- present. 2 2p orbitals have 1 e- each.

d subshell: double dumbells x y xy yz xz z2 x2-y2

Atomic Radii within a Group + e- Hydrogen (Z=1); Shell (n)=1 + e- 2e- Lithium (Z=3); n = 2 8e- 2e- + e- Sodium (Z=11); n = 3

e- 2e- e- 2e- e- 2e- e- 2e- e- 2e- e- e- e- + + + + + Boron (Z=5) Beryllium (Z=4) n = 2 Lithium (Z=3) n = 2 If protons were light bulbs….and electrons were moths…... B e- Li e- Be e-

e- 2e- e- 2e- e- 2e- Increasing Increasing + + + Boron (Z=5) Beryllium (Z=4) Boron (Z=5) Lithium (Z=3) Increasing Increasing

First Ionization Energy + e- H+ Hydrogen (Z=1) + e- 8e- 2e- + e- 2e- Li+ Lithium (Z=3) Sodium (Z=11) e- 8e- 2e- + Na+

First Ionization Energy Hydrogen (Z=1) e- + Decreasing Lithium (Z=3) + 2e- e- Sodium (Z=11) + 2e- 8e- e-

e- e- 2e- 2e- 2e- e- e- e- e- Decreasing 1 e- removed = 2s0 + + + + + + + + e- 2e- 2e- 2e- e- e- e- e- Beryllium (Z=4) 4 protons screened by 2 e- Boron (Z=5) 5 protons screened by 2 e- Lithium (Z=3) 3 protons screened by 2 e- 1 e- removed = 2s0 1 e- removed = 2s1 1 e- removed = 2s22p0 Decreasing

e- 2e- 2e- e- 2e- e- e- Decreasing Decreasing + + + + + + Beryllium (Z=4) 4 protons screened by 2 e- Boron (Z=5) 5 protons screened by 2 e- Lithium (Z=3) 3 protons screened by 2 e- Decreasing Decreasing

Trends in the Periodic Table Atomic Radii (Size) Increasing Increasing First Ionization Energy Decreasing Decreasing

Electron Affinity F- Fluorine (Z=9) 2e- 2e- e- 8e- 7e- Cl- + + 2e- 2e- e- 8e- 7e- Cl- Chlorine (Z=17) e- + + 2e- 2e- 8e- 8e- 7e- 8e-

Trends in the Periodic Table First Ionization Energy Decreasing Decreasing Decreasing Electron Affinity

Predicting Stable Ions Sodium (Z=11) + + 2e- 2e- 8e- 8e- e- Na+ Cl- Chlorine (Z=17) e- + + 2e- 2e- 8e- 8e- 7e- 8e-