How is a sodium ion formed from a sodium atom?

• A. It gains an electron
• B. It shares electrons
• C. It gains a proton
• D. It loses an electron

Answer: (D)

When atoms form ions, they do so by adjusting their outer electrons to reach a more stable arrangement. Sodium has one electron in its outer shell, which is relatively easy to remove. By losing that electron, the outer shell becomes full from the inner shells, giving a configuration similar to neon and a more stable state. Losing the electron leaves sodium with more protons than electrons, so it becomes positively charged—a sodium ion. The other ideas don’t fit this process: gaining an electron would create a negatively charged ion, sharing electrons is about covalent bonding rather than ion formation, and gaining a proton would change the element itself.