1.22 - Periodicity

Question 1

What is periodicity?

Answer 1

The regularly repeating pattern of atomic, physical and chemical properties with increasing atomic number

Question 2

What are examples of trends?

Answer 2

• Atomic radii
• Melting points
• Boiling points
• First ionisation energies

Question 3

How does atomic radius change across a period?

Answer 3

It decreases

Question 4

Why does this happen?

Answer 4

• Because the number of protons in the nucleus increases
• So the nuclear charge increases
• Which causes an increase in the attractive force between the nucleus and outer electrons
• Meaning that the size of the atom decreases

Question 5

What do elements with giant lattice structures have?

Answer 5

High melting and boiling points

Question 6

What do elements with simple molecular structures have?

Answer 6

Low melting and boiling points

Question 7

How does first ionisation energy generally change across a group?

Answer 7

It increases

Question 8

What are the anomalies to this trend?

Answer 8

Group 3 and Group 6 elements

Question 9

Why does the first ionisation energy drop for group 3 and group 6 elements?

Answer 9

Due to their electronic configurations

Question 10

Why is less energy required to remove an electron from a full orbital than a half-filled orbital?

Answer 10

Because in a full orbital, there is repulsion between the two electrons, meaning it is easier to remove one of the electrons as they are already providing part of the force required