Chemistry question

Question

6. In what respect does an atom of magnesium differ from a magnesium ion (Mg2+)? Could you explain how you got the correct answer?

(A) The ion has a more stable electronic arrangement than the atom.

(B)The positive charge on the nucleus of the ion is two units greater than the nuclear charge on the atom.

(C)The ion has two more protons than the atom.

(D)The ion will react more readily with free Cl.

(E)The ion has two more planetary electrons than the atom.

Answer 1

The correct answer is A.

An atom of magnesium has an electronic configuration of 1s²2s²2p⁶3s². It has 12 electrons, with two in its innermost shell and 10 in its valence shell. In contrast, a magnesium ion has lost two electrons from its valence shell, leaving it with an electronic configuration of 1s²2s²2p⁶, which is the same as the noble gas neon. This gives the ion a more stable electronic arrangement than the atom.

Option B is incorrect because the nuclear charge of the magnesium ion is still +12, the same as the nucleus of the magnesium atom.

Option C is incorrect because the number of protons in the nucleus of an atom determines its identity, so a magnesium ion and a magnesium atom have the same number of protons (12).

Option D is also incorrect because the reactivity of an ion with another species depends on several factors, such as the ion's charge, size, and electronic configuration. It cannot be determined solely based on the fact that the ion has lost electrons.

Option E is incorrect because the magnesium ion has two fewer electrons than the magnesium atom, not two more.

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