Why are sodium and potassium in the same group on the periodic table?

Question

1. They have similar atomic weights
2. They have similar reactivity
3. They are both hard and brittle
4. They are both colorless

Answer 1

2. They have similar reactivity

Sodium and potassium are both alkali metals and share similar chemical properties due to their valence electron configuration. They are highly reactive metals, readily forming positive ions (Na+ and K+) in chemical reactions. This similarity in reactivity is why they are placed in the same group (group 1) on the periodic table.