Which of these is an alkaline earth metal?

**The reasoning** Alkaline earth metals are **Group 2 elements** on the periodic table. They include Beryllium (Be), Magnesium (Mg), **Calcium (Ca)**, Strontium (Sr), Barium (Ba), and Radium (Ra). The name "alkaline earth" comes from their oxides, which form alkaline (basic) solutions in water. These metals have **2 valence electrons**, are shiny, and reactive (though less so than Group 1 metals). Calcium fits perfectly — it's the fifth most abundant element in Earth's crust and essential for bones and teeth. **Why the wrong options tempt you** - **Sodium (A)** is an *alkali metal* (Group 1, not Group 2) — easy to confuse because "alkaline" sounds like "alkali." - **Iron (C)** and **Copper (D)** are *transition metals* (found in the middle block of the periodic table) — they're commonly known metals, so you might guess them if unsure. **Quick takeaway** Remember: **Group 2 = Alkaline earth metals** (think "Be My Ca Sr Ba Ra" for the family), while Group 1 = Alkali metals. Calcium is your classic alkaline earth metal — strong bones need Group 2!