Chemistry of Life

matter

Anything that has mass and takes up space

element

A pure substance made of only one kind of atom

proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

electron

A subatomic particle that has a negative charge

atomic number

the number of protons in the nucleus of an atom

atomic mass

The average mass of all the isotopes of an element

isotope

Atoms of the same element that have different numbers of neutrons

orbitals

regions around the nucleus in which given electron or electron pair is likely to be found

valence shell

The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom.

chemical bond

the attractive force that holds atoms or ions together

molecule

two or more atoms held together by covalent bonds

macromolecule

A very large organic molecule composed of many smaller molecules

cation

A positively charged ion

anion

A negatively charged ion

electron transfer

movement of electrons from one element to another; important in creation of ionic bonds

ionic bond

Formed when one or more electrons are transferred from one atom to another

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

nonpolar

No partial charges. Do not mix with water.

polar

Molecule with partial charges. Mixes with water.

hydrogen bond

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

functional group

A specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and involved in chemical reactions.

hydrophilic

describes ions or polar molecules that interact well with other polar molecules such as water

hydrophobic

describes uncharged nonpolar molecules that do not interact well with polar molecules such as water

hydroxyl

OH-

methyl

CH3

carboxyl

COOH

phosphate

PO4 3-

acid

A substance that increases the hydrogen ion concentration of a solution.

base

A substance that decreases the hydrogen ion concentration in a solution.

pH scale

measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14

buffer

compound that prevents sharp, sudden changes in pH

reactant

A chemical substance that is present at the start of a chemical reaction

product

A substance produced in a chemical reaction

anabolic

A process in which large molecules are built from small molecules

catabolic

A process in which large molecules are broken down

enzyme

A type of protein that speeds up a chemical reaction in a living thing

catalyst

substance that speeds up the rate of a chemical reaction

substrate

A specific reactant acted upon by an enzyme

active site

a region on an enzyme that binds to a protein or other substance during a reaction

activation energy

the minimum amount of energy required to start a chemical reaction

open system

A system in which matter can enter from or escape to the surroundings.

closed system

A system in which no matter is allowed to enter or leave

entropy

A measure of disorder or randomness.

heat

The energy transferred between objects that are at different temperatures

adhesion

attraction between water molecules and other molecules

electronegativity

the ability of an atom to attract electrons when the atom is in a compound

nonpolar covalent bond

type of covalent bond that forms between atoms when electrons are shared equally between them

polar covalent bond

type of covalent bond that forms as a result of unequal electron sharing, resulting in creating slightly positive and negative charged molecule regions