2.2.1. Electron structure

Question 1

How many electrons can the 1st, 2nd, 3rd and 4th shell hold?

Answer 1

1 - 2
2 - 8
3 - 18
4 - 32

Question 2

Describe the difference between an orbital, sub shell and shell.

Answer 2

Orbital - region of space around nucleus which can contain up to two electrons
Sub shell - consist of one or more orbitals (s, p, d, f sub shells)
Shell - consist of one or more sub shells (1, 2, 3, 4 shell)

Question 3

Define atomic orbital

Answer 3

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

Question 4

What shape is an s orbital?

Answer 4

spherical

Question 5

What shape is a p-orbital?

Answer 5

dumb-bell shape

Question 6

How many orbitals are found in the s-, p- and d- sub-shells?

Answer 6

s - 1
p - 3
d - 5

Question 7

How many electrons can be held in the s-, p- and d- sub-shells?

Answer 7

s - 2
p - 6
d - 10

Question 8

Describe electrons in a box representation

Answer 8

• Arrows represent electrons
• Arrows point in opposite direction in the same orbital to represent opposite spin
• Electrons fill orbitals singly in the same energy level before pairing up

Question 9

What are the rules by which electrons are arranged in a shell?

Answer 9

• electrons added one at a time
• lowest energy level is filled first
• each energy level must be filled before the next
• each orbital filled singly before pairing
• 4s orbital is filled before 3d orbital

Question 10

why is the 4s orbital filled before 3d?

Answer 10

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

Question 11

What is the electron configuration of krypton? (Z = 36)

Answer 11

The full electron configuration for krypton (Kr) is:
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶

Question 12

What electrons are lost when a positive ion forms?

Answer 12

The electrons in the highest energy level