What is an atom? (2024)

FAQs

What is an atom very short answer? ›

An atom is a particle of matter that uniquely defines a chemical element. An atom consists of a central nucleus that is surrounded by one or more negatively charged electrons. The nucleus is positively charged and contains one or more relatively heavy particles known as protons and neutrons.

An atom is the basic building block of chemistry. It is the smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element.

Atom Examples

Carbon atom - Carbon atoms have an atomic number of 6 and typically have a mass of 12 amu. However, isotopes of carbon, such as carbon-14 will have different mass numbers due to differing numbers of neutrons. Oxygen atom - Oxygen atoms have an atomic number of 8 and typically have a mass of 16 amu.

Anything that has a mass—in other words, anything that occupies space—is composed of atoms. While its name originally referred to a particle that couldn't be divided any more—the smallest thing possible—we now know that each atom is generally made up of smaller particles.

An atom itself is made up of three tiny kinds of particles called subatomic particles: protons, neutrons, and electrons. The protons and the neutrons make up the center of the atom called the nucleus and the electrons fly around above the nucleus in a small cloud.

In fact, there are over 100 kinds of atoms. About 92 of them occur naturally, and the others have been made by scientists in the laboratory. There are hydrogen atoms, helium atoms, carbon atoms, oxygen atoms, and so on.

Atoms range in size from a few tenths of a nanometer to several nanometers across. More than 10 million hydrogen atoms would fit across the head of a pin. Atoms are the basic constituents of molecules, cells, humans, and planets. The human body contains about a billion billion billion (10^27) atoms.

An atom is an extremely small piece of matter. All normal matter – everything that has mass – is made of atoms. This includes solids, liquids, and gases. The atom cannot be broken to parts by chemistry, so people once thought it was the smallest piece of matter that could exist.

Atoms do exist but they are certainly not indivisible. As Democritus rightly guessed, atoms are the basic units of matter. Like Lego bricks, they can be put together in many different ways to make everything from viruses to Venus. But while Democritus' pictured solid atomos, real atoms are mostly empty space.

Atoms consist of three fundamental types of particles, protons, electrons and neutrons. Neutrons and protons have approximately the same mass and in contrast to this the mass of an electron is negligible. A proton carries a positive charge, a neutron has no charge and an electron is negatively charged.

Is an atom a thing? ›

Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons.

The universe is a vast range to consider and while knowing that all matter is composed of extremely small particles called atoms, it is estimated that there may be 10⁷⁸ to 10⁸² atoms in the known universe. What differentiates elements?