A lithium atom has three protons, three neutrons, and three electrons. What is the overall charge on this atom?
–3
0
+1
+3
The correct answer and explanation is:
The overall charge on a lithium atom is 0.
Here’s why:
- Protons: Lithium has 3 protons, which are positively charged. The positive charge of the protons is +3.
- Electrons: Lithium also has 3 electrons, which are negatively charged. The negative charge of the electrons is -3.
- Neutrons: Neutrons have no charge, so they don’t contribute to the overall charge of the atom.
In an atom, the number of protons and electrons determines the charge. Since a lithium atom has 3 protons and 3 electrons, their charges cancel each other out. The protons’ positive charge (+3) is exactly neutralized by the electrons’ negative charge (-3), resulting in a net charge of 0.
Thus, the lithium atom is electrically neutral. This is the case for all neutral atoms where the number of protons equals the number of electrons.
If the atom were to lose or gain electrons, it would no longer be neutral. For example, if it lost an electron, it would have 3 protons and 2 electrons, resulting in a +1 charge, creating a lithium ion (Li⁺). On the other hand, if it gained an electron, it would have 3 protons and 4 electrons, resulting in a -1 charge, forming a lithium ion (Li⁻). However, in this case, since the number of protons equals the number of electrons, the charge is 0.