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What is a molecule? | Science for Kids

When you look around, how many different textures and materials do you notice? It's hard to believe, but everything around is you made up of the same thing - atoms! Today we're molecules, which are a group of atoms bonded together.

Molecules are made up of two or more atoms, which are one of the smallest sizes of matter out there. While some molecules have only two atoms, others, like DNA, have thousands of atoms. If there is only one atom in a molecule, this is called a noble gas. For example, helium (He), the gas that makes balloons float, is a noble gas and a molecule of helium made up of just helium atoms.

While it's possible to break down molecules into their atoms, they won't share the same chemicals as the original anymore, making them an entirely new thing. For example, water is made up of two hydrogen atoms and one oxygen atom (written H2O). So a single molecule of water will have two hydrogen atoms and one oxygen. However, breaking down water even further makes hydrogen and oxygen, which is something completely different than water!

How do Atoms Make Molecules?

Atoms are made of a center part called the nucleus, which is made of protons and neutrons. Around the outside of the atom are electrons. If you've ever played with a magnet, you have a pretty good idea of how atoms stay together - they cling together like the force you feel when connecting the magnets. The neutrons and the protons in the nucleus of an atom are positive, while the electrons are negative; this is because the electrons stay near the nucleus like opposite sides of a magnet attract each other.

Since scientists know how atoms act, they can show how molecules attach. For example, when atoms are close, they can have their electrons interact. If these atoms interact the right way, they'll become a molecule. Molecules with two atoms that form thanks to a chemical reaction are diatomic (die-at-tom-ik). In comparison, molecules with more than two atoms are polyatomic (pol-ee-at-tom-ik).

What Do Molecules Look Like?

Since some molecules are tiny, it can be hard for scientists to capture exactly what they look like. However, there are ways to tell what forms molecules take based on their atoms' behavior. For example, the molecular shape shows scientists how molecules interact with each other. It also lets them know how that molecule will react to boiling or melting.

Electrons come in many different shapes, including linear molecules forming in a straight line, trigonal planar molecules almost like a triangle lying down, and more. These shapes all happen because the electron pairs want to be as far from each other as possible without running into another electron pair. Think about it like two people who want to hang out with each other but don't want to sit next to anyone else. So they're going to try and find a place far enough away from other people without running into another person, which is what electrons try and do with each other in a covalent bond.

Why Are Molecules Important?

Molecules make up almost everything on the planet and help scientists learn how the world works. Once you know about molecules, understanding why different chemical reactions happen can be a lot easier. In addition, because these atoms interact in specific ways, you can predict what will happen based on their shapes. Pretty cool, right? Check out this month's GIGIL STEM kit for more information about chemical reactions and building your own molecule model at home!


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