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

2 nd Term: subshell - designated by s, p,d,f 1s1s n = 2 n = 3 The first shell (1) has one subshell (s).

2 nd 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. 1s1s n = 2 n = 3 The first shell (1) has one subshell (s). The s subshell is spherical in shape and has 1 orbital 3rd Term: orbital

2 nd 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. 1s1s n = 2 n = 3 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 1s1s The first shell (1) has one subshell (s). The s subshell is spherical in shape and has 1 orbital H 1s 1 shell subshell # of electrons present energy H 1s  Electronic configuration Orbital Energy Level Diagram

The Electronic Configuration of Helium He: Atomic # of 2, 2 electrons in a neutral He atom 1s1s

The Electronic Configuration of Helium He: Atomic # of 2, 2 electrons in a neutral He atom H 1s 1 He 1s 2 He 1s  1s1s **if there are 2 electrons in the same orbital they must have the opposite spin. (Pauli ’ s Exclusion Principle)

1s1s The Electronic Configuration of Lithium (Li) Li: Z=3 Li has 3 electrons. 2 nd shell (2)

1s1s The Electronic Configuration of Lithium (Li) Li: Z=3 Li has 3 electrons. 2 nd shell - The 2nd shell (n= 2) has 2 subshells which are s and p. 2s2s 2p2p

1s1s The Electronic Configuration of Lithium (Li) Li: Z=3 Li has 3 electrons. 2 nd shell 2s2s 2p2p Li 1s 2 2s 1 2s  Li 1s  Electronic configurationOrbital Energy Level Diagram

1s1s The Electronic Configuration of Berylium (Be) Be: Z=4 Be has 4 electrons. 2 nd shell 2s2s 2p2p Be 1s 2 2s 2 2s  Be 1s  Electronic configurationOrbital Energy Level Diagram 

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 x y z 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 -

1s1s The Electronic Configuration of Boron (B) B: Z=5 B has 5 electrons. 2 nd shell 2s2s 2p2p 1s1s 2s2s 2p2p Be 1s 2 2s 2 2s  Be 1s  B 1s 2 2s 2 2p 1 2p  2s  B 1s 

1s1s The Electronic Configuration of Carbon (C) C: Z=6 C has 6 electrons. 2 nd shell 2s2s 2p2p 1s1s 2s2s 2p2p B 1s 2 2s 2 2p 1 2p  2s  B 1s  C 1s 2 2s 2 2p x 1 p y 1 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 xy z2z2 xz x y yz x 2- y 2

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

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

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

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

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

Lithium (Z=3) 3 protons screened by 2 e e-e- 2e - Beryllium (Z=4) 4 protons screened by 2 e - Boron (Z=5) 5 protons screened by 2 e e-e- 2e - e-e e-e- e-e- e-e e - removed = 2s 0 1 e - removed = 2s 1 1 e - removed = 2s 2 2p 0  Decreasing

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

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

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

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

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