9th grade biology chemistry of life

atom

the basic unit of matter

nucleus

the center of an atom, which contains the protons and neutrons

electron

a negatively charged particle; located in the space surrounding the nucleus

element

a pure substance that consists entirely of one type of atom

isotope

one of several forms of a single element, each of which contains the same number of protons but different numbers of neutrons

compound

a substance formed by the chemical combination of two or more elements in definite proportions

ionic bond

a chemical bond formed when one or more electrons are transferred from one atom to another

covalent bond

a type of bond between atoms in which the electrons are shared

molecule

the smallest unit of most compounds that displays all the properties of that compound

cohesion

the attraction between molecules of the same substance

adhesion

the force of attraction between different kinds of molecules

solution

a type of mixture in which all the components are evenly distributed

suspension

a mixture of water and nondissolved material

acid

a compound that releases +hydrogen ions (H ) in solution; a solution with a pH of less than 7

base

a compound that releases -hydroxide ions (OH ) in solution; a solution with a pH of more than 7

buffer

a compound that prevents sharp, sudden changes in pH

carbohydrate

a compound made up of carbon, hydrogen, and oxygen atoms; a type of nutrient that is the main source of energy for the body

lipid

a macromolecule made mostly from carbon and hydrogen atoms; includes fats, oils, and waxes

nucleic acid

a macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

protein

a macromolecule that contains carbon, hydrogen, oxygen, and nitrogen; needed by the body for growth and repair

amino acid

a compound with an amino group on one end and a carboxyl group on the other end

chemical reaction

the process that changes, or transforms, one set of chemicals into another set of chemicals

activation energy

the energy that is needed to get a reaction started

catalyst

a substance that speeds up the rate of a chemical reaction

enzyme

a protein catalyst that speeds up the rate of specific biological reactions