Question

question 1 in a reading, you come across a lithium atom represented as li^-. a neutral atom of lithium has 3 protons. what can you infer about the number and type of subatomic particles present in li^-? the lithium atom has lost a proton, so it now has 2 protons and 3 electrons. the lithium atom has gained a proton, so it now has 4 protons and 3 electrons. the lithium atom has lost an electron, so it now has 3 protons and 2 electrons. the lithium atom has gained an electron, so it now has 3 protons and 4 electrons.

Explanation:

A neutral lithium atom has 3 protons. In the given $Li^-$ ion, the negative charge indicates an extra electron. Since the number of protons defines the element and doesn't change in normal chemical - state changes, lithium always has 3 protons. The $Li^-$ ion has gained an electron. A neutral lithium atom has 3 electrons (equal to the number of protons for neutrality), and $Li^-$ has 4 electrons.

Answer:

The lithium atom has gained an electron, so it now has 3 protons and 4 electrons.