Question

which statement best explains why the overall charge on an atom is zero?
the positive charge of the neutrons in the nucleus equals the negative charge in the electron cloud.
the positive charge of the protons in the nucleus equals the negative charge in the electron cloud.
the negative charge of the neutrons in the nucleus equals the positive charge in the electron cloud.
the negative charge of the protons in the nucleus equals the positive charge in the electron cloud.

Explanation:

To determine why an atom has an overall zero charge, we recall atomic structure: protons (in the nucleus) have a positive charge, electrons (in the electron cloud) have a negative charge, and neutrons are neutral. For the overall charge to be zero, the positive charge from protons must balance the negative charge from electrons.

• Option 1: Neutrons are neutral, so their "charge" (which is zero) can’t equal electron charge. Eliminate.
• Option 2: Neutrons are neutral, so their "charge" (zero) can’t equal electron charge. Eliminate.
• Option 3: Protons have positive charge, electrons have negative charge. If the positive charge of protons equals the negative charge of electrons, their charges cancel, resulting in a net zero charge for the atom. This matches atomic theory.
• Option 4: Protons are positive, so their "negative charge" is incorrect (protons are positive, not negative). Eliminate.

Answer:

C. The positive charge of the protons in the nucleus equals the negative charge in the electron cloud.