Inorganic 1 Section 2 - Unit 8: Periodicity

Question 1

Write an equation, including state symbols, to show the process that occurs when the first ionisation energy of an element is measured (1 mark)

Answer 1

X(g) → X+(g) + e–

Question 2

State and explain the trend in atomic radius from phosphorus to chlorine (3 marks)

Answer 2

• Decreases
• Number of protons increases
• Attracting outer electrons in the same shell

Question 3

In terms of atomic structure, explain why the van der Waals’ forces in liquid argon are very weak (2 marks)

Answer 3

• Argon particles are single atoms with electrons closer to nucleus
• So they cannot easily be polarised

Question 4

Describe the bonding in metals (2 marks)

Answer 4

• Lattice of positive ions

- Surrounded by delocalised electrons

Question 5

Explain how metals conduct electricity (2 marks)

Answer 5

• Delocalised electrons

- Flow in a given direction

Question 6

Explain the meaning of the term periodicity as applied to the properties of rows of elements in the Periodic Table (2 marks)

Answer 6

• Trend in the properties of elements across a period

- Repeated in the next row

Question 7

Describe and explain the trend in atomic radius across a period (3 marks)

Answer 7

• Decreases across the row
• Since the number of protons increases
• So there’s more attraction for electrons in same shell

Question 8

Describe and explain the trend in electronegativity across a period (4 marks)

Answer 8

• Increases across the row
• Since the number of protons increases
• Atomic radius decreases
• More attraction for bonding or shared electrons

Question 9

Describe and explain the trend in conductivity across a period (4 marks)

Answer 9

• Decreases across the row
• Left hand side are metals
• Right hand side are non-metals
• Electrons free to move (or delocalised) in metals but aren’t able to in non-metals