Lesson · P.5.1

Atomic structure and electric charge

Protons, neutrons and electrons and the charges they carry, why opposite charges attract and like charges repel, and how moving electrons become the electric current the HESI A2 physics subtest builds the rest of its electricity questions on.

ObjectiveP.5.1Read4 minExam weightElectricity and Magnetism ≈ 16% of Physics

This lesson is part of the full Study Guide

Unlock every lesson, unit, and quiz across every subject. The Physics electricity and magnetism unit is included.

See editions and pricing →

What you will be able to do

You can name the three subatomic particles and state the charge each one carries.
You can find the net charge of an ion and predict whether two charged objects will attract or repel.
You can explain what electric current is and calculate it from a charge and a time.

What the lesson concludes

Protons carry a positive charge, neutrons carry none, and electrons carry a negative charge equal in size but opposite in sign.
An atom becomes a charged ion by gaining or losing electrons, never by gaining or losing protons, and its net charge equals protons minus electrons.
Like charges repel and opposite charges attract, and a bigger charge or a shorter distance makes that push or pull stronger.
Electric current is charge in motion: current equals charge divided by time, measured in amperes.
A wire carries current as moving electrons, while the body's nerves and heart carry it as moving ions instead.