an atom with a positive or negative net charge is called an ion. select all of the models of ions. proton…

Explanation:

Step1: Recall ion definition

An ion has unequal protons and electrons.

Step2: Analyze first model

In the first model, there are 5 protons and 2 electrons. Since $5\neq2$, it is an ion.

Step3: Analyze second model

In the second model, there are 4 protons and 1 electron. Since $4\neq1$, it is an ion.

Step4: Analyze third model

In the third model, there is 1 proton and 1 electron. Since $1 = 1$, it is a neutral atom, not an ion.

Step5: Analyze fourth model

In the fourth model, there are 3 protons and 1 electron. Since $3\neq1$, it is an ion.

Answer:

The first, second, and fourth models are ions.