2.2.1 Electron Structure

Principal quantum number

The shell occupied by the electrons

Shell

A group of orbitals with the same principal quantum number

1st shell capacity

2

2nd shell capacity

8

3rd shell capacity

18

4th shell capacity

32

Orbital

A region around the nucleus that can hold up to two electrons with opposite spins

Orbital capacity

2

Types of orbitals

●s orbital ●p orbital ●d orbital ●f orbital

Shape of s-orbital

Spherical

Shape of p-orbital

Dumb-bell shape

Orbitals in S subshell

1

Electrons in S subshell

2

Orbitals in P subshell

3

Electrons in P subshell

6

Orbitals in D subshell

5

Electrons in D subshell

10

Orbitals in F subshell

7

Electrons in F subshell

14

Electrons in box representation

Arrows

Shell number representation

n

S orbital presence

n = 1

P orbital presence

n = 2

D orbital presence

n = 3

F orbital presence

n = 4

Rules for electron arrangement in shell

●Electrons are added one at a time ●Lowest available energy level is filled first ●Each energy level must be filled before the next one can fill ●Each orbital is filled singly before pairing ●4s is filled before 3d

4s vs 3d filling

4s orbital has a lower energy than 3d before it is filled

Electron configuration of krypton

1s22s22p63s23p64s23d104p6

Electrons lost in positive ion formation

Electrons in the highest energy levels