Atoms and Elements

Flashcards covering key vocabulary related to atoms, elements, and their properties.

Atom

The smallest particle of an element that retains the characteristics of that element.

Element

A pure substance that cannot be broken down into simpler substances and consists of atoms with the same number of protons.

Molecule

A group of two or more atoms bonded together.

Compound

A substance formed when two or more elements are chemically bonded together.

Homogeneous mixture

A mixture in which the composition is uniform throughout.

Heterogeneous mixture

A mixture in which the composition is not uniform throughout.

Chemical symbol

A one or two-letter abbreviation for an element's name.

Atomic number

The number of protons in the nucleus of an atom, which determines the element's identity.

Mass number

The total number of protons and neutrons in an atomic nucleus.

Isotope

Atoms of the same element that have different mass numbers due to a different number of neutrons.

Electron energy levels

Regions around the nucleus where electrons are likely to be found.

Valence electrons

Electrons in the outermost energy level that determine an element's chemical properties.

Ionization energy

The energy required to remove an outermost electron from an atom.

Metalloids

Elements that have properties of both metals and nonmetals; found along the zigzag line in the periodic table.

Periodic table

A table that organizes all known elements according to their atomic number and properties.