chemical bond that involves sharing of electron pairs between atoms.

Covalent bond

a horizontal row of the periodic table.


the number of protons in the nucleus of an atom. It determines the chemical properties of an element and its place on the periodic table.

Atomic number

a combination two or more pure substances that retain their chemical properties.

Heterogeneous mixture

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


- very small particle of matter that has no electrical charge and is part of all atoms except hydrogen


number of protons and neutrons of an atom (an average).

Atomic mass

a mixture that is uniform in composition throughout.

Homogenous mixture

smallest particle of a substance that can only exist by itself or be combined with other atoms to from a molecule.


substances produced by the reaction on the right-hand side of the chemical equation.


very small particle of matter that is part of the nucleus of an atom.


One of the basic substances that are made of atoms of one kind and cannot be separated into simpler substances.


a number that follows the elements, usually written lower, that represents the number of atoms in a compound.


the positively charged central core of an atom, consisting of protons, neutrons and containing most of the mass.


when a positively charged ion forms a bond with a negatively charged ion and one atom transfers the electron to another.

Ionic bond

a column of elements on the t=periodic table that have similar characteristics.


a substance that takes part in and undergoes change during a reaction.


- an arrow that separates the two sides of a chemical equation

Yield sign

any chemical element that is an effective conductor of electricity and heat.


a symbolic representation of a chemical reaction in the form of symbols and formulas.

Chemical equation

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