ap bio unit 1

element

pure substance that consists entirely of one type of atom

compound

A substance made up of atoms of two or more different elements joined by chemical bonds

essential elements

elements that an organism needs to live a healthy life and reproduce

trace elements

required by an organism in only minute quantities

mass number

the sum of the number of neutrons and protons in an atomic nucleus

atomic number

the number of protons in the nucleus of an atom

number of neutrons

mass number - atomic number

isotopes

Atoms with the same number of protons but different numbers of neutrons

atomic mass unit

a unit of mass that describes the mass of an atom or molecule

radioactive isotope

An isotope that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy.

chemical energy

Energy stored in chemical bonds

potential energy

stored energy

valence shell

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

chemical bonds

An attraction between two atoms resulting from sharing outer-shell electrons or the presence of opposite charges

covalent bonds

Bonds created by sharing electrons with other atoms

molecule

two or more atoms held together by covalent bonds

electronegativity

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

nonpolar covalent bond

equal sharing of electrons

polar covalent bond

A covalent bond between atoms that differ in electronegativity; electrons are pulled closer to the more electronegative atom

ions

positively and negatively charged atoms

cation

positive ion

anion

negative ion

ionic bond

A chemical bond resulting from the attraction between oppositely charged ions

ionic compounds

compounds composed of cations and anions

emergent property

a property of a system that emerges from the interaction of the elements of the system

hydrogen bond

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

Van der Waals interactions

individually weak interactions that occur only when atoms and molecules are very close together

chemical reactions

the making and breaking of chemical bonds, leading to changes in the composition of matter

reactants

elements or compounds that enter into a chemical reaction

products

the elements or compounds produced by a chemical reaction

chemical equilibrium

a state of balance in which the rate of a forward reaction equals the rate of the reverse reaction

polar molecule

molecule with an unequal distribution of charge, resulting in a positive end and negative end

cohesion

an attraction between molecules of the same substance

adhesion

attraction between molecules of different substances

surface tension

a measure of how difficult it is to stretch or break the surface of a liquid

kinetic energy

the energy an object has due to its motion

thermal energy

the total energy of all the particles of an object

calorie

amount of energy needed to raise the temperature of 1 gram of water 1°C

kilocalorie

a unit of energy equal to 1,000 calories

joule

SI unit of energy

specific heat

the amount of energy required to raise the temperature of 1 gram of a substance by 1°C

heat of vaporization

the quantity of heat a liquid must absorb for 1 g of it to be converted from liquid to gas

evaporative cooling

the process in which the surface of an object becomes cooler during evaporation because the molecules with the greatest kinetic energy leave

solution

homogeneous mixture

solvent

a liquid substance capable of dissolving other substances

solute

the substance that is dissolved

hydration shell

the sphere of water molecules around a dissolved ion

hydrophilic

attracted to water

hydrophobic

water hating

molecular mass

the sum of the masses of all the atoms in a molecule

molarity

moles of solute/liters of solution

hydrogen ion

a positively charged ion (H+) formed from a hydrogen atom that has lost its electron

hydroxide ion

OH-

hydronium ion

a hydrogen ion combined with a water molecule, H3O+

acid

a substance that increases the hydrogen ion concentration of a solution

base

a substance that decreases the hydrogen ion concentration of a solution

pH

hydrogen ion concentration

buffer

compound that prevents sharp, sudden changes in pH

ocean acidification

decreasing pH of ocean waters due to absorption of excess atmospheric CO2 from the burning of fossil fuels

organic compound

compounds that contain carbon

macromolecule

large molecule formed by joining smaller organic molecules together

hydrocarbons

organic molecules consisting only of carbon and hydrogen

isomers

compounds with the same formula but different structures

structural isomers

have different covalent arrangements of their atoms

cis-trans isomers

have the same covalent bonds but differ in spatial arrangements

enantiomers

isomers that are mirror images of each other

functional groups

chemical groups attached to carbon skeletons that give compounds their functionality

adenosine triphosphate

compound used by cells to store and release energy (ATP)

polymer

large compound formed from combinations of many monomers

monomer

small chemical unit that makes up a polymer

enzymes

proteins that speed up chemical reactions

dehydration synthesis

a chemical reaction in which two molecules are bonded together with the removal of a water molecule

hydrolysis

breaking down complex molecules by the chemical addition of water

carbohydrates

the starches and sugars present in foods

monosaccharides

glucose, fructose, galactose (simple sugars)

disaccharides

sucrose, lactose, maltose

polysaccharides

large macromolecules formed from monosaccharides

glycosidic linkage

a covalent bond formed between 2 monosaccharides by a dehydration reaction

starch

storage form of glucose in plants

glycogen

an extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch

cellulose

a substance made of sugars that is common in the cell walls of many organisms

chitin

a structural polysaccharide consisting of amino sugar monomers, found in fungal cell walls and arthropod exoskeletons

fat

a large lipid molecule made from glycerol and three fatty acids; a triglyceride; most fats function as energy-storage molecules

fatty acid

an organic acid contained in lipids, such as fats or oils

saturated fatty acid

a long-chain hydrocarbon with single covalent bonds in the carbon chain; the number of hydrogen atoms attached is maximized

unsaturated fatty acid

a fatty acid that has one or more double bonds between carbons in the hydrocarbon tail

phospholipid

a molecule in biological membranes having a polar, hydrophilic head and nonpolar, hydrophobic tails

steroids

lipids characterized by a carbon skeleton consisting of four fused rings

cholesterol

a lipid that is an essential component of animal cell membranes and a precursor for other steroids

catalysts

substances that speed up chemical reactions

polypeptide

long chain of amino acids that makes proteins

protein

chains of amino acids

amino acid

compound with an amino group and a carboxyl group

peptide bond

covalent bond formed between amino acids

nucleic acid

macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

deoxyribonucleic acid

DNA

ribonucleic acid

RNA

polynucleotides

polymers of nucleic acids

nucleotides

basic units of DNA, composed of a sugar, phosphate, and nitrogenous base

pyrimidine

a nitrogenous base with a single-ring structure; thymine, cytosine, or uracil