Question

For the A groups (Groups 1A to 8A), how does the group number relate to the electron arrangement in atoms of the group?

Responses

The group number is equal to the number of electrons in the element.

The group number is equal to the number of electrons in the element.

The group number is equal to the number of times the element can be ionized.
The group number is equal to the number of times the element can be ionized.

The group number is equal to the block number of the sublevel.

The group number is equal to the block number of the sublevel.

The group number is equal to the number of electrons in the outermost shell.

Answer 1

Correct choice: "The group number is equal to the number of electrons in the outermost shell."

Explanation: For the main-group (A) elements, groups 1A–8A correspond to 1–8 valence electrons, which determine the elements' chemical behavior (e.g., 1A = 1 valence e−, 2A = 2 valence e−, 7A = 7 valence e−, 8A = noble gases with a full outer shell). Note the common caveat: helium is in group 8A but has only 2 valence electrons (a filled 1s shell). Also be aware modern IUPAC group numbering runs 1–18, but the valence-electron pattern for the main-group elements remains the same.