Chapter 2 - Chemistry of Life - Holt McDougal Biology

atom

Smallest basic unit of MATTER

element

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

compound

Substance made of atoms of DIFFERENT elements that are bound together in a particular ratio.

isotope

Atoms that have the same number of protons but different number of NEUTRONS (Ex C-12, C-13, C-14)

ion

An atom that has gained or lost one or more ELECTRONS; will be positive or negative

ionic bond

Type of BOND that forms when electrons are TRANSFERRED from one atom to another

covalent bond

Type of BOND that forms when atoms SHARE a pair of electrons

molecule

Two or more atoms held together by covalent bonds

hydrogen bond

An attraction between a slightly positive hydrogen atom and a slightly negative atom
(Example: Between water molecules --> Causing cohesion)

cohesion

The attraction between like substances

adhesion

The attraction between different substances

solution

Mixture of two or more substances that is homogenous (same throughout)

solvent

In a solution, the substance in which the solute dissolves.

solute

The substance that dissolves in a solvent (what "you" put in)

acid

A compound that release hyrdogen ions (H+) when dissolved in water; higher H+ concentration. pH below 7

base

A compound that releases hydroxide (OH-) ions in a solution; has a lower hydrogen ion concentration in a solution. pH above 7

pH

Measuring unit for acidity. (acids <7, bases >7)

monomer

a building block of a polymer

polymer

A large molecule (macromolecule) made of many monomers bonded together.

carbohydrate

Molecules composed of carbon, hydrogen and oxygen in a 2:1 ratio of H to O (carb= carbon, hydrate=water) (Ex. monosaccharides and polysaccharides)

lipid

Nonpolar molecules that include fats, oils, and cholesterol (This organic polymer is composed of 1 glycerol + 3 fatty acids)

fatty acid

One of the building blocks (monomer) that makes up lipids

protein

An organic polymer composed of monomers called amino acids

amino acids

Any one of 20 different organic molecules that combine to form proteins

nucleic acids

Polymers that are made up of monomers called nucleotides (Ex: DNA & RNA)

chemical reactions

Process that changes substances into different substances by breaking and forming chemical bonds

reactants

Substances that participates a chemical reaction (Left side of arrow)

product

Substance formed in a chemical reaction (Right side of arrow)

bond energy

The amount of energy that will break a bond between two atoms

equilibrium

The state reached when both reactants and products are made at the same rate.

activation energy

Energy needed to get a reaction started

exothermic

A chemical reaction in which energy is GIVEN OFF in the form of heat (Also exergonic reaction)

endothermic

A chemical reaction that TAKES IN or REQUIRES heat energy (Also endergonic reaction)

catalyst

A substance that decreases the activation energy needed to start a chemical reaction. (So... It speeds up the reaction)

enzymes

BIological catalysts for chemical reactions in LIVING THINGS; made of proteins

substrates

Specific reactants that an enzyme acts on

polar molecule

a molecule that has a partial positive end and a partial negative end because of unequal sharing of electrons

dehydration synthesis reaction

A chemical reaction in which two molecules are bonded together with the removal of a water molecule. (Ex - Monosaccharides bond together through this process to form polysaccharides)

hydrolysis reaction

A chemical reaction that breaks apart a larger molecule by adding a molecule of water (Ex - Proteins break down into amino acids through hydrolysis)