2.2 Electron structure (orbitals)

Question 1

How many electrons fill the first 4 shells?

Answer 1

1st shell: 2
2nd shell: 8
3rd shell: 18
4th shell: 32

Question 2

What is the rule used to figure out the maximum number of electrons that can fill each shell?

Answer 2

2n2

Question 3

What does ‘n’ represent in 2n2?

Answer 3

the shell number

Question 4

What is an orbital?

Answer 4

• A region in space where one is most likely to find an electron.
• An orbital can hold up to two electrons with opposite spins

Question 5

Why do the electrons in orbitals have opposite spins?

Answer 5

to reduce repulsion, as like charges repel

Question 6

How do you represent electrons in an orbital?

Answer 6

Box notation, where the box is the orbital and the half-headed arrows are electrons

Question 7

What is the shape of an s-orbital?

Answer 7

spherical shape

Question 8

What is the maximum number of electrons that can be found in an s-orbital?

Answer 8

2 electrons

Question 9

What is the maximum number of electrons that can be found in an s-subshell?

Answer 9

2 electrons

Question 10

What is the shape of a p-orbital?

Answer 10

dumb-bell shape

Question 11

What is the maximum number of electrons that can be found in a p-orbital?

Answer 11

2 electrons

Question 12

What is the maximum number of electrons that can be found in a p-subshell?

Answer 12

6 electrons

Question 13

What is the shape of a d-orbital?

Answer 13

various

Question 14

What is the maximum number of electrons that can be found in a d-orbital?

Answer 14

2 electrons

Question 15

What is the maximum number of electrons that can be found in a d-subshell?

Answer 15

10 electrons

Question 16

What does 1s2 mean?

Answer 16

1 means n = 1
s means s orbital
2 means the number of electrons in that orbital

Question 17

Why is the 4s orbital filled out before the 3d orbital?

Answer 17

• The energy levels get closer in distance, so there is an overlap between these energy levels
• so the 4s orbital is at a lower energy level than the 3d orbital

Question 18

When a sub-shell is built up with electrons, why are each orbital filled singly before pairing starts?

Answer 18

This is to minimise repulsion

Question 19

What are the two discrepancies with electron configuration?

Answer 19

Copper and Chromium

Question 20

Why are copper and chromium discrepancies?

Answer 20

As an electron flies off the 4s orbital into the next as half filled orbitals are more stable

Question 21

State what is meant by ‘Ionisation energy’?

Answer 21

The energy required to remove one electron from each atom in a mol of atoms in the gaseous state

Question 22

What are the 3 factors affecting ionization energy?

Answer 22

1. Nuclear charge
2. Atomic radius
3. Electron Shielding

Question 23

Explain the factor Nuclear charge

Answer 23

• The greater the nuclear charge (number of protons) the greater the nuclear attraction
• So more energy is required to remove the outermost electron
• So ionization energy is higher

Question 24

What is nuclear attraction?

Answer 24

The force of attraction between the outermost electron and the nucleus

Question 25

Explain the factor of Atomic radius

Answer 25

• The greater the atomic radius, the weaker the nuclear attraction
• so less energy is needed to remove the outermost electron
• So ionization energy is lower

Question 26

Explain the factor of electron shielding

Answer 26

• The greater the electron shielding, the weaker the nuclear attraction
• So less energy is needed to remove the outermost electron
• so ionization energy is lower

Question 27

What is electron shielding?

Answer 27

Inner electrons repelling outer electrons

Question 28

What are the 2 trends for ionization energy?

Answer 28

1. As you go across a period, ionization energy increases
2. As you go down a group, ionization energy decreases

Question 29

Why does ionization energy increase across a period?

Answer 29

• nuclear charge increases across a period
• atomic radius gets smaller
• electron shielding has no effect as there is the same number of shells
• so nuclear attraction increases
• so more energy is required to remove an electron
• so ionization energy increases

Question 30

Why does ionization energy decrease down a group?

Answer 30

• atomic radius increases
• electron shielding increases
• therefore nuclear attraction decreases
• therefore less energy is required to remove an electron
• so ionization energy decreases

Question 31

What are the discrepancies for ionization energy?

Answer 31

• Mg and AL
• P and S

Question 32

Why does Aluminum (13) have a lower ionization energy than Magnesium (12)?

Answer 32

• The outermost electron in the 3p orbital in Aluminium has a higher energy than electrons in the 3s orbital in Magnesium.
• Therefore less energy is needed to remove an electron from the 3p orbital In Aluminium
• so Aluminium has a lower ionization energy than Magnesium

Question 33

Why does sulphur (16) have a lower ionisation energy than phosphorous (15)?

Answer 33

• The electrons in the 3p orbital in Sulphur are paired whereas the electrons in the 3p orbital of Phosphorus are unpaired.
• Paired electrons repel more than unpaired electrons.
• Therefore less energy is needed to remove an electron from a paired 3p orbital in sulphur.
• So sulphur has a lower ionization energy than Phosphorus.