Ch. 2 Flashcard Terms

atom

the basic unit of matter

nucleus

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

electron

negatively charged particle; constantly moving around the nucleus

element

pure substance that consists entirely of one type of atom

isotope

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

compound

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

ionic bond

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

ion

atom that has a positive or negative charge

covalent bond

type of bond between atoms in which the electrons are shared

molecule

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

van der Waals forces

weak attraction that develops between oppositely charged regions of nearby molecules

hydrogen bond

weak attraction between a slightly positive hydrogen atom and another atom that is slightly negative

cohesion

attraction between molecules of the same substance

adhesion

force of attraction between different kinds of molecules

monomer

small chemical unit that makes up a polymer

polymer

molecules composed of many monomers; makes up macromolecules

carbohydrate

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

lipid

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

nucleotide

subunit of which nucleic acids are composed; made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

nucleic acid

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

protein

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

amino acid

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

chemical reaction

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

reactant

elements or compounds that enter into a chemical reaction

product

elements or compounds produced by a chemical reaction

activation energy

energy that is needed to get a reaction started

catalyst

substance that speeds up the rate of a chemical reaction

enzyme

protein catalyst that speeds up the rate of specific biological reactions

substrate

reactant of an enzyme-catalyzed reaction