Introduction to Atoms and Elements

Flashcards covering key terms and definitions related to atoms and elements.

Element

A fundamental substance containing one kind of atom, determined by the number of protons, that cannot be broken down into simpler substances by chemical reactions.

Atom

The smallest unit of matter composed of protons, neutrons, and electrons; atoms make up all living and nonliving matter.

Protons

Positively charged subatomic particles found in an atom's nucleus, determining the element's atomic number.

Atomic number

A unique number assigned to each element equal to the number of protons in an atom.

Neutrons

Subatomic particles located in an atom's nucleus that have no charge and determine the element's isotope.

Isotopes

Atoms of a particular element that differ in the number of neutrons.

Electrons

Negatively charged subatomic particles that orbit the nucleus and participate in chemical reactions.

Electron shells

Orbits around an atom's nucleus where electrons are located; the outermost shell participates in chemical reactions.

Valence shell

The outermost electron shell of an atom, where electrons determine the atom's chemical behavior.