Magnesium and calcium have similar chemical properties because their atoms in the ground state have:

• A. the same atomic radius
• B. the same number of valence electrons
• C. the same number of protons
• D. the same electronegativity

Answer: (B)

Verified step by step guidance

1. Understand that elements in the same group of the periodic table have similar chemical properties because they have the same number of valence electrons, which are the electrons in the outermost shell involved in chemical bonding.
2. Identify that magnesium (Mg) and calcium (Ca) are both in Group 2 (alkaline earth metals) of the periodic table, meaning they each have two valence electrons.
3. Recognize that atomic radius, number of protons, and electronegativity differ between magnesium and calcium because calcium has more electron shells and more protons, affecting these properties.
4. Recall that the chemical behavior of elements is primarily determined by their valence electrons, not by atomic radius, number of protons, or electronegativity alone.
5. Conclude that magnesium and calcium have similar chemical properties because they have the same number of valence electrons.