Biology Chapter 2

Atom

smallest basic unit of matter

Compound

substance made of atoms of different elements that are bonded together in a particular ratio.

Covalent Bond

chemical bond formed when two atoms share one or more pairs of elections.

Electron

its negative charge in the atom

Element

substance made of only one type of atom that cannot be broken down by chemical means.

Ion

atom that has gained or lost electrons

Ionic Bond

chemical bond formed between oppositely charged ions.

Molecule

two or more atoms held together by covalent bonds.

Neutron

no charge in the atom its found in the nucleus in the atom

Nucleus

center of atom

Proton

positive charge in the atom found in the nucleus in the atom

Acid

compound that donates a proton (H+) when dissolved in a solution.

Adhesion

attraction between molecules of difference substances

Base

compound that accepts a proton (H+) when dissolved in solution.

Cohesion

attraction between molecules of the same substances.

Hydrogen Bond

attraction between a slightly positive hydrogen atom and a slightly negative atom.

pH

measurement of acidity; related to free hydrogen material of organisms.

Solute

substance that dissolves in a solvent and is present at lower concentration

Solution

mixture that is consistent throughout; also called homogenous mixture.

Solvent

substance in which dissolve and that is present in greatest concentration in a solution.

Amino Acid

molecule that makes up proteins of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur

Carbohydrate

molecule made of carbon, hydrogen, and oxygen; includes sugars and starches.

Fatty Acid

hydrocarbon chain often bonded to glycerol in a lipid.

Lipid

nonpolar molecule made of carbon, hydrogen, and oxygen; includes fats and oils.

Monomer

molecule that binds with others to make a polymer

Nucleic Acid

polymer of nucleotides; the genetic material of organisms.

Polymer

large, carbon-based molecule made of repeating monomers

Protein

polymer composed of amino acids linked by peptide bonds

Activation Energy

energy needed to start a chemical reaction.

Bond Energy

amount of energy needed to break a bond between two particular atoms; or the amount of energy released when a bond forms between two particular atoms.

Chemical Reaction

process in which substances change into different substances through the breaking and forming of chemical bonds

Endothermic

chemical reaction that requires to be added

Equilibrium

when reactants and products of a chemical reaction are formed at the same rate

Exothermic

chemical reaction that yields a net release of energy in the form of heat

Product

substance formed by a chemical reaction.

Reactant

substance that dissolves in a solvent and is present at lower concentration than the solvent

Catalyst

substances that decreases activation energy and increase reaction rate in a chemical reaction

Enzyme

protein that catalyzes chemical reaction for organisms

Substrate

reactant in a chemical reaction upon which an enzyme acts.

Atomic Number

determined by number of protons, different for each element

Mass Number

determined by neutrons and protons combined, may differ in isotopes

Nonpolar Covalent Bond

this is the type of bond that holds the two oxygen atoms together in O2

Polar Covalent Bond

this is the type of bond that holds one of the hydrogen atoms to the oxygen atom in H2O