Question

Chlorine, bromine and iodine are elements in group VII of the periodic table. Describe the trend in color and physical state at room temperature and pressure as the atomic number increases.

Answer 1

Hint: Chlorine, bromine and iodine are called halogens and belong to p-block in the periodic table. As we are moving from top to bottom in the periodic table along the group atomic number increases and atomic size also increases.

Complete answer:
- Halogens show a smooth variation in the physical properties as we are moving from top to bottom in the periodic table.
- The physical state chlorine at room temperature and pressure is gaseous.
- The physical state bromine at room temperature and pressure is a corrosive liquid.
- The physical iodine chlorine at room temperature and pressure is solid.
- All the halogens are colored due to the absorption of light from the visible region.
- The color of chlorine is greenish yellow, the color of bromine is red and the color of iodine is violet.
- The boiling point of the halogens increases as we are moving from top to bottom in the periodic table due to the increase in Van der Waals force of attraction.

Note:
All halogens are non-metals means they won’t lose electrons. The Van der Waals force of attraction is the main reason behind the increase in boiling points of the halogens and causes the change in physical state of the halogens as we are moving top to bottom in the periodic table.