Chemistry

Atom

The smallest unit of an element that retains the properties of that element.

Ion

An atom or molecule that has gained or lost one or more electrons, resulting in a net charge.

Element

A pure substance that cannot be broken down into simpler substances by chemical means.

Compound

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

Molecule

Two or more atoms bonded together, which can be the same or different elements.

Mixture

A combination of two or more substances that are not chemically combined.

Protons

Positively charged subatomic particles found in the nucleus of an atom.

Neutrons

Neutral subatomic particles found in the nucleus of an atom.

Electrons

Negatively charged subatomic particles that orbit the nucleus of an atom.

Atomic number

The number of protons in the nucleus of an atom, which defines the element.

Atomic mass

The weighted average mass of an element's isotopes, measured in atomic mass units (amu).

Electron arrangement

The distribution of electrons in the shells around an atom's nucleus.

Metals

Elements that are typically shiny, malleable, ductile, and good conductors of heat and electricity.

Non-metals

Elements that are generally poor conductors of heat and electricity and have various physical properties.

Group 17

Known as the halogens, this group includes elements such as fluorine and chlorine.

Group 18

Known as the noble gases, this group includes elements such as helium and neon.

Ionic bonding

A type of chemical bond that occurs between metals and non-metals, involving the transfer of electrons.

Covalent bonding

A type of chemical bond that occurs between non-metals, involving the sharing of electrons.

Metallic bonding

A type of chemical bonding that occurs within metals due to a sea of delocalized electrons.

Chemical reaction

A process that involves the transformation of reactants into products.

Precipitate

An insoluble solid that forms when two liquids react with each other.

Collision theory

A theory that states that reactants must collide with sufficient energy and proper orientation to react.

Rate of reaction

The speed at which reactants are converted into products in a chemical reaction.

Catalyst

A substance that increases the rate of a chemical reaction without itself undergoing any permanent change.