What do you call a hydrogen atom that has lost its electron?

• A. Hydrogen
• B. Proton
• C. Neutron
• D. Hydrogen Ion

Answer: (D)

Losing the electron leaves behind a positively charged species because electrons carry negative charge. The remaining particle is the hydrogen nucleus, which is just a single proton. In chemistry and physics this charged form is called a hydrogen ion (H+). It’s essentially the same thing as a proton, but the term hydrogen ion emphasizes its ionized state after electron removal. The other options describe either a neutral atom (hydrogen), a neutron (a neutral particle with no charge), or the nucleus itself without implying ionization (a proton). So the appropriate name for a hydrogen atom that has lost its electron is a hydrogen ion.