Molecules Definition: Lesson for Kids

Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Would you like to know what a molecule is? In this lesson, you'll learn the definition of a molecule and discover where molecules are found, what they're made of, and how they're built.

What is a Molecule?

Take a look at your hand. The only thing you can see is a palm with fingers, but if you could look inside, you'd see that your hand is made up of many parts, like bones and muscles. Look through a microscope, and you'd notice that those bones and muscles are made of cells. Turn up the magnification, and you'd discover that each cell contains molecules.

So, your body is made up of molecules. Molecules don't just make up your body; they also make up the things around you. There are molecules in your desk, your pencil, and your lunch.

When two or more atoms join together, they form a molecule.

A molecule is a group of two or more atoms that bond together. Atoms are the basic building blocks of matter. You might have seen a picture of an atom before. It has a nucleus in the middle and electrons floating around it.

A good way to think about atoms and molecules is to think of the letters that make up a word. For example, the word 'dog' is made up of three letters, d-o-g. Those letters are the smallest units, so they are like atoms. The letters join to make a word, so the word is like a molecule.

DNA is a big molecule with a spiral shape.

There are many ways to put atoms together. The number atoms and type of atoms that bond together to form a molecule determine the size and shape of the molecule. Hydrogen gas (H2) is a small molecule that's made up of just two hydrogen atoms joined side-by-side. DNA is a complex molecule that carries your genetic information. It's made up of many different atoms that bond together to form a spiral shape.

How Molecules are Built

To better understand molecules, let's build a water molecule. A water molecule is sometimes referred to as H2O, which is its chemical structure. So, every molecule of water has two hydrogen atoms (H2) and one oxygen atom (O).

A water molecule consists of two hydrogen atoms and one oxygen atom.

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