Elements in the same group of the periodic table have the same
Answer and explanation
Correct answer: A. number of outer-shell electrons
- Step 1: The number of outer electrons decides the group and the chemical behaviour. Answer: number of outer-shell electrons. Why not the others: number of shells: The number of shells increases down a group. mass number: Mass number increases down a group. number of neutrons: Neutron numbers differ between elements.
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