Chemistry Terms

acid

substance that donates or releases hydrogen ions (H⁺) when it ionizes in water

adenosine triphosphate (ATP)

energy-storing and-transferring molecule found in all cells

alkaline

pH scale of 14; basic range

anion

a negatively charged ion

aqueous solution

a solution in which water is the solvent

atom

fundamental unit of an element; the smallest part of the element that has the characteristics of that element

atomic number

the number of protons in the nucleus of an atom

base

substance, such as the hydroxyl ion (H-), that combines with hydrogen ion (H+)

catalysts

chemical substances that speed up the rate of a chemical reaction

cation

positively charged ion

colloid

a mixture in which one substance is evenly distributed throughout another substance; the particles do not settle out. Milk and blood are colloids

compound

substance composed of two or more chemical elements, such as water (H2O)

covalent

bond or attraction formed by the sharing of electrons between atoms

electrolyte

compound that dissociates into ions when dissolved in water

element

substance composed of only one type of atom

energy

ability to perform work

enzyme

organic catalyst; speeds up the rate of a chemical reaction

hydrogen bond

weak intermolecular bond formed between hydrogen and a negatively charged atom such as oxygen or nitrogen

ionic bond

bond formed by the exchange of electrons between atoms

ionization

the dissociation of an electrolyte into its ions

ions

atoms that carry an electrical charge

isotope

an atom that has the same number of protons and electrons but a different number of neutrons; it has the same atomic number but a different atomic mass

matter

anything that occupies space and has mass

mixture

combination of two or more substances that can be separated by ordinary physical means

molecule

chemical combination of two or more atoms

neutralized

eliminated

pH

a measure of the hydrogen ion (H+) concentration

polar molecule

a molecule, such as water, that is uncharged but has an uneven distribution of charge; one end of the molecule is positive while the other is negative

precipitate

the solid deposit formed in a chemical reaction

radioactivity

spontaneous disintegration of atomic nuclei whereby rays of energy or particles are emitted

solute

a substance that is dissolved in another substance (solvent)

solutions

are mixtures; in a solution, the particles that are mixed together remain evenly distributed

solvent

substance in which the solute is dissolved or mixed

suspensions

are mixtures; in a suspension, the particles are relatively large and tend to settle to the bottom unless the mixture is shaken continuously