2.2.1 Electron structure

How many electrons fill the first shell?

2

How many electrons fill the second shell?

8

How many electrons fill the third shell?

18

How many electrons fill the fourth shell?

32

** What is an atomic orbital?

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

What shape is an s orbital?

Sphere

What is the shape of a p orbital?

Dumbbell

What are the subshells called?

s, p, d, f

How many orbitals in each subshell?

s- 1

p- 3

d- 5

f- 7

How many electrons can each subshell hold?

s- 2

p- 6

d- 10

f- 14

What rule do you follow when filling shells?

Fill in order of increasing energy levels:

1s , 2s , 2p , 3s , 3p , 4s , 3d , 4p

(4s has more energy than 3d)

What rule do you follow when filling orbitals?

Fill each orbital singly first, then pair them

What rule do you follow when taking electrons when forming ions?

Take from the highest energy orbital

(when filled, 4s is higher energy than 3d so take from 4s first)

How can you write shorthand electron configuration?

Use the noble gas that comes before the element in square brackets [] then add the remaining configuration

What is the electron configuration of Sc 3+ (Sc has 21 electrons)?

1s2 2s2 2p6 3s2 3p6

What’s the electron configuration of Mn 2+ (25 electrons normally)?

1s2 2s2 2p6 3s2 3p6 3d5

How many p orbitals are occupied in:

1s2 2s2 2p6 3s2 3p4 ?

6