Halogen Properties and Trends

IGCSE Edexcel Chemistry
2.5-2.6 Halogen properties and trends
Key Concept: Halogens are diatomic molecules with colors and states that change down the group as molecular size increases.

Section A: Colors and States

1. Complete the table for the halogens at room temperature. [4]
Halogen State Color
Fluorine
Chlorine
Bromine
Iodine
2. Describe the trend in color down Group 7. [1]
3. Describe the trend in state and melting/boiling points down Group 7. [2]

Section B: Explaining the Trend

4. Explain why melting and boiling points increase down the group. [3]
5. Predict the state and color of astatine at room temperature. [2]

Total marks: 12

Mark Scheme

1. F2: gas, pale yellow; Cl2: gas, green-yellow; Br2: liquid, red-brown; I2: solid, grey/black (purple vapor) [4]
2. Colors get darker down the group [1]
3. Gas to liquid to solid; melting/boiling points increase down group [2]
4. Larger molecules have more electrons and stronger intermolecular forces; more energy needed [3]
5. Solid, very dark/black [2]