# Electricity explained The science of electricity

## Everything is made of atoms

To understand electricity, some basic information about atoms is helpful. Atoms are the building blocks of the universe. Everything in the universe is made of atoms—every star, every tree, and every animal. The human body is made of atoms. Air and water are made of atoms, too. Atoms are so small that millions of them would fit on the head of a pin.

## Atoms are made of even smaller particles

The center of an atom is called the nucleus. The nucleus is made up of particles called protons and neutrons. Electrons spin around the nucleus in shells. If the nucleus was the size of a tennis ball, the atom would be the size of a sphere about 1,450 feet in diameter, or about the size of one of the largest sports stadiums in the world. Atoms are mostly empty space.

If the naked eye could see an atom, it would look a little like a tiny cluster of balls surrounded by giant invisible bubbles (or shells). The electrons would be on the surface of the bubbles, constantly spinning and moving to stay as far away from each other as possible. Electrons are held in their shells by an electrical force.

The protons and electrons of an atom are attracted to each other. They both carry an electrical charge. Protons have a positive charge (+) and electrons have a negative charge (-). The positive charge of the protons is equal to the negative charge of the electrons. Opposite charges attract each other. An atom is in balance when it has an equal number of protons and electrons. The neutrons carry no charge, and their number can vary.

The number of protons in an atom determines the kind of atom, or element, it is. An element is a substance consisting of one type of atom. The Periodic Table of Elements shows elements with their atomic numbers—the number of protons they have. For example, every atom of hydrogen (H) has one proton and every atom of carbon (C) has six protons.

## Electricity is the movement of electrons between atoms

Electrons usually remain a constant distance from the atom's nucleus in precise shells. The shell closest to the nucleus can hold two electrons. The next shell can hold up to eight. The outer shells can hold even more. Some atoms with many protons can have as many as seven shells with electrons in them.

The electrons in the shells closest to the nucleus have a strong force of attraction to the protons. Sometimes, the electrons in an atom's outermost shells do not have a strong force of attraction to the protons. These electrons can be pushed out of their orbits. Applying a force can make them shift from one atom to another. These shifting electrons are electricity.

## Static electricity exists in nature

Lightning is a form of electricity. Lightning is electrons moving from one cloud to another or electrons jumping from a cloud to the ground. Have you ever felt a shock when you touched an object after walking across a carpet? A stream of electrons jumped to you from that object. This is called static electricity.

Have you ever made your hair stand straight up by rubbing a balloon on it? If so, you rubbed some electrons off the balloon. The electrons moved into your hair from the balloon. The electrons tried to get far away from each other by moving to the ends of your hair. They pushed against or repelled each other and made your hair move. Just as opposite charges attract each other, like charges repel each other.

Last reviewed: December 19, 2022