Question

Given below are a few elements.

Li, K, Ca, F

Identify the element which:

1. has the least atomic radius.
2. has two valence electrons.
3. is the most electropositive.

Answer 1

1. Least atomic radius: Fluorine (F). Atomic radius decreases from left to right across a period; since Fluorine is at the far right of Period 2, it is the smallest among these.
2. Two valence electrons: Calcium (Ca). Calcium belongs to Group 2 (alkaline earth metals), which all have two electrons in their outermost shell.
3. Most electropositive: Potassium (K). Electropositivity increases down a group and to the left across a period. Potassium is an alkali metal in Period 4, making it more electropositive than Li, Ca, or F.