Chemistry for Biology Vocabulary

acid
A substance that increases the hydrogen ion concentration of a solution.
aqueous solution
A mixture of two or more substances, one of which is water.
atom
The smallest unit of matter that retains the properties of an element.
atomic number
The number of protons in the nucleus of an atom, unique for each element and designated by a subscript to the left of the elemental symbol.
base
A substance that reduces the hydrogen ion concentration of a solution.
buffer
A substance that consists of acid and base forms in a solution and that minimizes changes in pH when extraneous acids or bases are added to the solution.
cell
The simplest collection of matter that can live.
chemical bond
An attraction between two atoms resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms; the bonded atoms gain complete outer electron shells.
chemical reaction
A process leading to chemical changes in matter; involves the making and/or breaking of chemical bonds.
cohesion
The binding together of like molecules, often by hydrogen bonds.
community
All the organisms that inhabit a particular area; an assemblage of populations of different species living close enough together for potential interaction.
compound
A substance containing two or more elements in a fixed ratio; for example, table salt NaCl.
covalent bond
A type of strong chemical bond in which two atoms share one pair of valence electrons.
ecosystem
All the organisms in a given area as well as the abiotic factors with which they interact; a community and its physical environment.
electron
A subatomic particle with a single negative charge; one or more electrons move around the nucleus of an atom.
evaporative cooling
Surface cooling that results when a substance evaporates. This occurs because the "hottest" molecules vaporize first
heat
The total amount of kinetic energy due to molecular motion in a body of matter. Heat is energy in its most random form.
hydrogen bond
A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.
ion
An atom that has gained or lost electrons, thus acquiring a charge.
ionic bond
A chemical bond resulting from the attraction between oppositely charged ions.
isotope
One of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass.
mass number
The sum of the number of protons and neutrons in an atom's nucleus.
matter
Anything that takes up space and has mass.
molecule
Two or more atoms held together by covalent bonds.
neutron
An electrically neutral particle (a particle having no electrical charge), found in the nucleus of an atom.
organ system
A group of organs that work together in performing vital body functions.
organ
A specialized center of body function composed of several different types of tissues.
organism
An individual living thing.
pH scale
A measure of hydrogen ion concentration equal to -log [H+] and ranging in value from 0 to 14.
polar molecule
A molecule (such as water) with opposite charges on opposite sides.
population
A group of individuals of one species that live in a particular geographic area.
product
An ending material in a chemical reaction.
proton
A subatomic particle with a single positive electrical charge, found in the nucleus of an atom.
radioactive isotope
An isotope (an atomic form of a chemical element) that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy.
reactant
A starting material in a chemical reaction.
solute
A substance that is dissolved in a solution.
solution
A homogeneous, liquid mixture of two or more substances.
solvent
The dissolving agent of a solution. Water is the most versatile solvent known.
temperature
A measure of the intensity of heat in degrees, reflecting the average kinetic energy of the molecules.
tissue
An integrated group of cells with a common structure and function.
trace element
An element indispensable for life but required in extremely minute amounts.