matter
Anything that occupies space and has mass.
element
Pure substance that cannot be broken down chemically into simpler kinds of matter.
compound
A pure substance that is made up of atoms of two or more elements.
chemical reaction
Any process in which a chemical change occurs.
reactants
Shown on the left side of the equation; starting materials.
products
Shown on the right side of the equation; ending materials.
acid
Compound that has a pH below 7.
base
Compound that has a pH above 7.
neutral
Substance with a pH of exactly 7.
pH scale
0 to 14 scale that measures the acidity or basicity of substances; each step on the scale represents a tenfold change in acidity or basicity.
cohesion
Attractive force between particles of the same kind (such as water molecules "sticking" to other water molecules).
adhesion
Attractive force between unlike substances (such as water molecules sticking to other substances or surfaces).
surface tension
Results from cohesion of water molecules on the surface of a body of water; allows some organisms to walk on water.
monomer
Building Block;" smaller compound which must be joined together with other small compounds to build larger molecules.
polymer
Molecule consisting of linked units or building blocks (monomers).
macromolecule
VERY large polymer that typically consists of thousands of units.
polymerization
The process by which large compounds are constructed by joining together smaller compounds.
dehydration synthesis
Two or more monomers are combined to form larger molecules; water is lost during this polymerization reaction.
hydrolysis
A molecule of water is added to break apart the bond between two or more joined monomers; occurs when large molecules are split apart.
ATP
Stores and transports energy from one part of the cell to another.
carbohydrate
Known as "sugars and starches;" built from monosaccharides.
monosaccharide
Simplest carbohydrate; used to build bigger carbohydrates; examples include glucose, fructose, and galactose.
disaccharide
Double sugar" formed by joining two monosaccharides; examples include sucrose (table sugar), lactose, and maltose.
polysaccharide
Complex carbohydrate formed by joining three or more monosaccharides; examples include starch, glycogen, and cellulose.
protein
Built from amino acids joined by peptide bonds; these molecules have many roles in the cell and are generally considered to be "workers.
enzyme
A type of protein that speeds up the rate of a chemical reaction (a catalyst).
lipid
Built from one glycerol and three fatty acids; substances are typically oily or waxy; used for energy storage and cell membranes.
saturated fat
Fat that contains all single bonds; contains maximum number of hydrogen atoms and forms straight chains. (Solid at room temperature.)
unsaturated fat
Fat that contains one or more double bonds; does not contain maximum number of hydrogen atoms and forms "kinked" chains. (Liquid at room temperature.)
nucleic acid
Built from nucleotides; store and transmit genetic information; examples include DNA and RNA.