Atomic number	Mass number	Reactant	pH scale	Product
The number of protons in the nucleus of an atom	The sum of the numbers of protons and neutrons in the nucleus of an atom	A substance that enters into and is altered in the course of a chemical reaction	A numerical measure of the acidity or alkalinity of a chemical solution	A substance that forms in a chemical reaction

The positively changed central portion of an atom that comprises nearly all of the atomic mass and that consists of protons and neutrons	Neither acid nor basic; pH is 7	A change in the identity or characteristics of an atomic nucleus that results when it is bombarded with an energetic particle	An atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons	An atom or group of atoms that carries a positive or negative charge as a result of having lost or gained one or more electrons
Nucleus	Neutral	Nuclear reaction	Isotope	Ion

Atom	Endothermic reaction	Exothermic reaction	Fission	Fusion
The smallest particle of an element that can exist either alone or in combination	A chemical reaction that requires heat	A chemical reaction in which heat is released to the surroundings	The splitting of an atomic nucleus resulting in the release of large amounts of energy	The union of atomic nuclei to form heavier nuclei resulting in the release of enormous quantities of energy

Element	Neutron	Proton	Electron	Ionic bond
Any of more than 100 fundamental substances that consist of atoms of only one kind and that singly or in combination constitute all matter	A subatomic particle that has no charge and that is found in the nucleus of an atom	A subatomic particle that has a positive electrical charge and is found in the nucleus of an atom	A subatomic particle that has a negative electrical charge	A bond formed by the attraction between oppositely charged ions

Base	Chemical change	Physical change	Chemical reaction	Covalent bond
Any compound that increases the number of hydroxide ions (OH^-) when dissolved in water; pH of greater than 7	A change in a substance resulting in an entirely different substance with different properties from the first (ex: combustion)	A change in a substance that does not alter its chemical makeup (ex: phase change)	A process that involves rearrangement of the molecular or ionic structure of a substance; it can be represented using a chemical equation	A bond that forms when atoms share one or more pairs of electrons

Acid

Any compound that increases the number of hydronium ions (H₃0⁺) when dissolved in water; pH of less than 7