# Question Video: Selecting the Correct Statement for a Nonmetal Atom When It Gains Electrons Science

Which of the following is correct for a nonmetal atom when it gains electrons? [A] Its outer electron shell is filled with electrons. [B] It changes into a negative ion. [C] The number of negative charges in the ion is equal to the number of electrons gained. [D] The number of electrons in the ion formed is more than the number of protons in it. [E] All of the answers are correct.

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### Video Transcript

Which of the following is correct for a nonmetal atom when it gains electrons? (A) Its outer electron shell is filled with electrons. (B) It changes into a negative ion. (C) The number of negative charges in the ion is equal to the number of electrons gained. (D) The number of electrons in the ion formed is more than the number of protons in it. (E) All of the answers are correct.

The question talks about a nonmetal atom. We know that in the center of any atom is the nucleus. The nucleus contains positively charged particles called protons. And it contains neutral particles called neutrons. Outside the nucleus are negatively charged particles called electrons. Electrons are arranged into different energy levels, or shells, each with different energies.

Nonmetal atoms tend to have more than four electrons in their outer shell, which is the reason why nonmetals gain electrons when they react, as we shall understand in a moment. For example, here is the electronic configuration of an atom of the nonmetal oxygen. The nucleus has eight protons, since this is the atomic number of oxygen. We aren’t interested in the number of neutrons in this question. So we won’t draw them in. An atom is neutral overall. So the number of protons must equal the number of electrons. And so we can deduce that this atom must have eight electrons.

These eight electrons are arranged in the energy levels as follows. There are two electrons in energy level K and six electrons in energy level L. Energy level L can hold a maximum of eight electrons. We can see that energy level L is not yet full.

When a nonmetal atom reacts, it tends to gain electrons. Why is this? For any atom to be stable, their outer energy level should ideally be full. Since oxygen’s outer energy level contains six electrons, it requires less energy for an oxygen atom to gain two electrons to fill this shell than to lose all six electrons in this shell. So, oxygen atoms tend to gain two electrons when they react to get a full outer shell which is very stable. Thus, we can see that answer (A) ⁠— its outer electron shell is filled with electrons — is a true statement for a nonmetal atom gaining electrons.

When a neutral atom gains electrons, it becomes negatively charged. We can see that there are eight positive protons and 10 negative electrons now. The number of protons and electrons is no longer equal. The atom has changed into a negative ion. (B) — it changes into a negative ion — is also a true statement.

We can see that for this oxygen ion, two negative electrons were gained. So the ion has an overall charge of two minus. In other words, the number of negative charges in the ion is equal to the number of electrons gained. So, statement (C) is also true.

Since a negative ion has more electrons than protons, we can conclude that statement (D) is also true. The number of electrons in the ion formed is more than the number of protons in it.

Since statements (A), (B), (C), and (D) are all true statements for a nonmetal atom gaining electrons, we can conclude that the correct answer for this question is (E). All of the answers are correct.