2.1 Periodicity

Question 1

What are electron shells really called?

Answer 1

Energy levels

Question 2

What is the formula to work out the maximum number of electrons in an energy level?

Answer 2

2n^2

Question 3

What are the energy sub levels?

Answer 3

S P D

Question 4

Are electrons divided equally between sub levels?

Answer 4

No

Question 5

Why don’t we know where electrons are at all times?

Answer 5

They exhibit wave particle duality

Question 6

What is an orbital?

Answer 6

A volume of space that can hold a maximum of 2 electrons

Question 7

How many orbitals and maximum electrons does the sub level S have? Which groups?

Answer 7

1 orbital
2 electrons

Group 1 and 2

Question 8

How many orbitals and maximum electrons does the sub level P have? Which groups?

Answer 8

3 orbitals
6 electrons

Groups 3-0

Question 9

How many orbitals and maximum electrons does the sub level D have? Which groups?

Answer 9

5 orbitals
10 electrons

Transition metals

Question 10

How does the electron configuration progress?

Answer 10

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p

Question 11

What happens the more energy levels there are?

Answer 11

The further away from the nucleus the more energy they have

Question 12

How can we shorten electron configurations?

Answer 12

Using the noble gases in square brackets

These indicate a full energy levels

Question 13

What are the two abnormalities in electron configuration?

Answer 13

Chromium (Cr)

Copper (Cu)

Question 14

What is the correct configuration of Chromium? Why?

Answer 14

[Ar] 4s1 3d5

Chromiums outer shell is half full so it loses an electron out of the s group and gains one in the d group

Question 15

What is the correct configuration of Copper? Why?

Answer 15

[Ar] 4s1 3d10

Coppers outer shell is full so it loses an electron out of the s group and gains one in the d group

Question 16

What does each sub level contain?

Answer 16

Electron orbitals which are regions of space in which are electrons are likely to be found

Question 17

How is the electron configuration of d block ions different?

Answer 17

When d block elements form ions they lose s group electrons rather than d group

Question 18

How can we represent electrons within sub levels?

Answer 18

Using spin diagrams

Question 19

What properties do electrons have to do with their positions?

Answer 19

They have a property called spin

It tells us how they occupy orbitals

Question 20

What are the two rules with spin diagrams?

Answer 20

2 electrons in the same orbital cannot have the same spin state
(Up then down)

Electrons always go into unoccupied orbitals first
(Up, up, up then down, down, down)
(Remember: look for a free seat on the bus)

Question 21

What is first ionisation energy?

Answer 21

The energy required to remove one mole of electrons from one mole of atoms in the gaseous state

Or energy to remove the outer electron

Question 22

What must elements be in ionisation energy?

Answer 22

A Gas

Question 23

How do we remove an electron? What is ionisation energy measured in?

Answer 23

Heat energy is supplied to overcome the attraction of the electrons to the nucleus

Question 24

How do you write the equations for ionisation energy?

Answer 24

X - any element

X(g) —> X(g)+ + e-
X(g)+ —> X(g)2+ + e-
X(g)2+ —> X(g)3+ + e-

Endothermic reactions

Question 25

What happens to ionisation energy within individual elements? Why?

Answer 25

It increases

By making the ion positively charged it is harder to remove the next electron as the ion want to hold on to the remaining electrons

It requires more energy to remove the next one

Question 26

What is changing across a period?

Answer 26

More protons are added therefore the outermost electron has a stronger electrostatic force of attraction to the nucleus

Question 27

What is significant about electrons added across a period?

Answer 27

They are added within the same principle energy level therefore aren’t further from the nucleus

They are actually closer as atomic radius decreases

Question 28

Why for individual elements does the ionisation energy vastly increase between 3s1 and 2p6?

Answer 28

The sub level is closer to the nucleus so more energy is required to remove the electron due to a stronger attraction

Question 29

What is the general pattern of first ionisation energy across period 2 or 3? Anomalies?

Answer 29

It generally increases across a period

Between 3s2 and 3p1
Then 3p3 and 3p4

They are slight decreases

Question 30

What is the general trend of first ionisation down a group? Why?

Answer 30

It decreases

Less energy is required as the increase in energy levels means the electrostatic force of attraction is weaker to the nucleus

Question 31

Why is there a decrease in ionisation energy between Mg and Al across period 3?

Answer 31

Mg - 3s2
Al - 3p1

Aluminium’s outer most electron is slightly further away from the nucleus which shows it requires less energy

Despite having more protons

Question 32

Why is there a decrease in ionisation energy between P and S across period 3?

Answer 32

P - 3p3
S - 3p4

Sulphur’s outer electron is paired with an electron in an orbital therefore a slight repulsion occurs

It has a lower ionisation energy as it is slightly easier to remove