atom

Also known as atom of element

Atoms are the basic particles of the chemical elements and the fundamental building blocks of matter. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element.

AI overview

An atom is the smallest unit of a chemical element and the fundamental building block of all matter, consisting of a nucleus containing protons and neutrons surrounded by electrons held in place by electromagnetic forces. Atoms matter because the number of protons they contain determines what chemical element they are, and this atomic composition is what gives all materials their properties and determines how they behave and interact with one another.

AI-generated from the Wikipedia summary — may contain errors.

~54 min read

Encyclopedic overview

34 sections

Contents

History of atomic theory
Philosophy
Dalton's law of multiple proportions
Discovery of the electron
Discovery of the nucleus
Bohr model
Discovery of protons and neutrons
The current consensus model
Structure
Subatomic particles
Nucleus
Electron cloud
Properties
Nuclear properties
Mass
Shape and size
Radioactive decay
Magnetic moment
Energy levels
Valence and bonding behavior
States
Identification
Origin and current state
Formation
Earth
Rare and theoretical forms
Superheavy elements
Exotic matter
See also
Notes
References
Bibliography
Further reading
External links

Atoms are extremely small, typically around 100 picometers across. A human hair is about a million carbon atoms wide. Atoms are smaller than the shortest wavelength of visible light, which means humans cannot see atoms with conventional microscopes. They are so small that accurately predicting their behavior using classical physics is not possible due to quantum effects.

Excerpted from Wikipedia’s “atom” article, available under the CC BY-SA 4.0 licence.