Question

a neutral atom of lithium has 3 protons. what can you infer about the number and type of particles present in li⁺? choose the best answer.
a. this lithium atom has gained a proton, so it now has 4 protons and 3 electrons.
b. this lithium atom has lost an electron, so it now has 3 protons and 2 electrons.
c. this lithium atom has lost a proton, so it now has 2 protons and 3 electrons.
d. this lithium atom has gained an electron, so it now has 3 protons and 4 electrons.

Explanation:

Step1: Recall atomic - ion relationship

A neutral atom has equal number of protons and electrons. Lithium has 3 protons in its nucleus. The symbol Li⁺ indicates a positive ion.

Step2: Understand ion - formation

A positive ion is formed when an atom loses an electron. Since the atomic number (number of protons) of lithium is 3 and it is now Li⁺, it has lost 1 electron. So, it has 3 protons and 2 electrons.

Answer:

The lithium atom has lost an electron, so it now has 3 protons and 2 electrons.