An atom is a tiny, tiny bit of matter. It’s really hard to imagine how small an atom is. Suppose you could line atoms up in row. It would take 100 million atoms to make a row only 1 centimeter long.

Everything in the world is made of atoms. The chair you are sitting on, the computer you are looking at, the clothes you are wearing, and even your body are all made of atoms.

There are more than 100 kinds of atoms. Each kind of atom belongs to a different element, such as oxygen or iron.

An element is the simplest kind of substance there is, made up of only one kind of atom. Oxygen is the element made up of only oxygen atoms. Iron is the element made up of only iron atoms.

DO ATOMS HAVE PARTS?

All atoms have the same basic parts. Most of the matter in an atom is at its center, which is called the nucleus. The nucleus of nearly all atoms is made of two more parts called protons and neutrons. Protons and neutrons consist of even tinier parts called quarks.

Electrons whirl around the nucleus but at some distance. The distance between electrons and the nucleus means that most of an atom is empty space. Scientists do not think that electrons are made of any more parts.

Each type of atom has a different combination of protons, neutrons, and electrons. The number of protons determines what kind of chemical element the atom is. The difference in number of protons explains why oxygen differs from iron.

WHO DISCOVERED ATOMS?

Atoms are not a new discovery. Ancient Greeks came up with the idea of atoms around 400 bc. But the ancient Greeks did not understand what atoms were really like. Scientists made many discoveries about the structure and nature of atoms during the 1900s. They used big machines called atom smashers, or particle accelerators, to smash parts of atoms together. Then they studied the pieces. They learned that powerful forces hold each tiny atom together. They learned how to release this power called atomic energy or nuclear energy. They built atomic bombs using this energy. They also built nuclear power plants that use atomic energy to make electricity.

 Source: Microsoft ® Encarta

Twitter