To which group do the alkaline earth metals such as radium, barium and strontium belong?

Correct — C. Radium, barium and strontium all sit in the second column of the periodic table — Group 2, written 2A in the older American labelling the paper uses.

Every element in that column has two electrons in its outermost shell. It loses both to reach a stable arrangement and forms a 2+ ion, which is why the whole family behaves alike.

The column runs beryllium, magnesium, calcium, strontium, barium, radium, and is called the alkaline earth metals because their oxides are basic and were once classed as earths.

Why the others are wrong

• (a)
  Group 3A — Group 3A is the boron family — boron, aluminium, gallium — with three outer electrons and a 3+ ion. Aluminium is a metal, but nothing in this column is an alkaline earth metal.
• (b)
  Group 1A — Group 1A is the alkali metals: lithium, sodium, potassium, caesium. One outer electron and a 1+ ion, and a name close enough to 'alkaline earth' that it is put on the page precisely to catch you.
• (d)
  Group 5A — Group 5A is the nitrogen family — nitrogen, phosphorus, arsenic — with five outer electrons and a largely non-metallic character, so it cannot hold a set of metals at all.

The periodic table's groups are its columns, and a column is a family because every member has the same number of valence electrons. That count, not atomic weight or date of discovery, decides how an element reacts.

Group 2 metals carry two valence electrons, lose both, and form 2+ ions. They are harder, denser and higher-melting than the alkali metals next door, and they react with water far less violently — calcium fizzes in cold water where sodium can ignite.

Two numbering systems overlap in Indian textbooks: the modern IUPAC 1 to 18, and the older A/B scheme in which Group 2 is Group IIA, or 2A.

Key facts

• The alkaline earth metals are Group 2 (IIA/2A): beryllium, magnesium, calcium, strontium, barium, radium.
• Every Group 2 atom has two valence electrons and forms a 2+ ion.
• Group 1 holds the alkali metals, a separate family from the alkaline earths of Group 2.
• Radium is radioactive and was discovered by Marie and Pierre Curie.

Common traps

• Reading 'alkaline earth' as a longer name for 'alkali' and answering Group 1A
• Counting columns from hydrogen and landing one group off
• Assuming a radioactive element such as radium must sit outside the main groups

No directly related past PYQ was found.