AP Bio chemistry of life vocab

compound

a substance consisting of two or more different elements combined in a fixed ratio

element

any substance that cannot be broken down to any other substance by chemical reactions

essential elements

a chemical element required for an organism to survive, grow, and reproduce

trace elements

an element indispensable for life but required in extremely minute amounts

matter

anythting that takes up space and has mass

neutrons

a subatomic particle having no electrical charge (electrically neutral), with a mass of about 1.7 x 10^-24 g, found in the nucleus of an atom

protons

a subatomic particle with a single positive electrical charge, with mass of about 1.7 x 10^-24 g, found in the nucleus of an atom

electrons

a subatomic particle with a single negative electrical charge and a mass about 1/2,000 that of a neutron or proton. One or more BLANK move around the nucleus of an atom

atom

the smallest unit of matter that retains the properties of an element

atomic nucleus

an atom's dense central core, containing protons and neutrons

dalton

a measure of mass for atoms and subatomic particles; the same as the atomic mass unit or amu

atomic number

the number of protons in the nucleus of an atom, unique for each element and designated by a subscript

mass number

the sum of the number of protons and neutrons in an atom's nucleus

atomic mass

the total mass of an atom, the numerically equivalent to the mass in grams of 1 mole of an atom. (For an element with more that on isotope, the atomic mass is the average mass of the naturally occurring isotopes weighted by their abundance.)

isotopes

one of several atomic forms of an element, each with the same number of protons, but a different number of neutrons, thus differing in atomic mass

radioactive isotope

an isotope (an atomic form of a chemical element) that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy

half-life

the amount of time it takes for 50% of a sample of a radioactive isotope to decay

radiometric dating

a method for determining the absolute age of rocks and fossils, based on the half-life of radioactive isotopes

energy

the capacity to cause change, especially to do work (to move matter against an opposite force)

potential energy

the energy that matter possesses as a result of its location or spatial arrangement (structure)

electron shells

an energy level of electrons at a characteristic average distance from the nucleus of an atom

valence electrons

an electron in the outermost electron shell

valence shell

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

orbital

the three-dimensional space where an electron is found 90% of the time

chemical bonds

an attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells

molecule

two or more atoms held together by covalent bonds

valence

the bonding capacity of a given atom; usually equals the number of unpaired electrons required to complete the atom's outermost (valence) shell

single bond

a single covalent bond; the sharing of a pair of valence electrons by two atoms

electronegativity

the attraction of a given atom for the electrons of a covalent bond

nonpolar covalent bond

a type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity

polar covalent bond

a covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive

ions

an atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge

cations

a positively charged ion

anions

a negatively charged ion

ionic bond

a chemical bond resulting from the attraction between oppositely charged ions

hydrogen bond

a type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule

van der Waals interactions

weak attractions between molecules or parts of molecules that result from transient local partial charges

ionic compounds

a compound resulting from the formation of an ionic bonds; also called a salt

salts

a compound resulting from the formation of an ionic bond; also called an ionic compound

reactants

a starting material in a chemical reaction

products

a material resulting from a chemical reaction

chemical equilibrium

in a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentration of the reactants and products do not change with time

chemical reactions

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

polar molecule

a molecule (such as water) with an uneven distribution of charges in different regions of the molecule

cohesion

the linking together of like molecules often by hydrogen bonds

adhesion

the clinging of one substance to another, such as water to plant cell walls by means of hydrogen bonds

surface tension

a measure of how difficult it is to stretch or break the surface of a liquid. Water has a high surface tension because of the hydrogen bonding of surface molecules

kinetic energy

the energy associated with the relative motion of objects. Moving matter can perform work by imparting motion to other matter

thermal energy

kinetic energy due to the random motion of atoms and molecules; energy in its most random form

temperature

a measure in degrees of the average kinetic energy (thermal energy) of the atoms and molecules in a body of matter

heat

thermal energy in transfer from one body of matter to another

calorie(cal)

the amount of heat energy required to raise the temperature of 1 gram of water by 1 degree Celsius. The BLANK, usually used to indicate the energy content of food, is a kilocalorie

kilocalorie(kcal)

a thousand calories; the amount of heat energy required to raise the temperature of 1 kg of water by 1 degree Celsius

joule (J)

a unit of energy: 1 J= 0.239 cal

specific heat

the amount of heat that must be absorbed or lost for 1 g of a substance to change its temperature by 1 degree Celsius

heat of vaporization

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

evaporative cooling

the process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid gaseous state

solution

a liquid that is a homegenous mixture of two or more substances

solvent

the dissolving agent of a solution. Water is the most versatile solvent known

solute

a substance that is dissolved in a solution

aqueous solution

a solution in which water s the solvent

hydration shell

the sphere of water molecules around a dissolved ion

hydrophobic

having no affinity for water; tending to coalesce and form droplets in water

hydrophilic

having an affinity for water

molecular mass

the sum of the masses of all the atoms in a molecule; sometimes called molecular weight

mole (mol)

the number of grams of a substance that equals its molecular or atomic mass in daltons; a BLANK contains Avogadro's number of the molecules or atoms in question

molarity

a common measure of solute concentration, referring to the number of moles of solute per liter of solution

hydroxide ion

a water molecule that has lost a proton: OH-

hydrogen ion

a single proton with a charge of 1+. The dissociation of a water molecule (H2O) leads to the generation of a hydroxide ion (OH-) and a hydrogen ion (H+); in water, H+ is not found alone but associates with a molecule or in another region of the same molecule

hydronium ion

a water molecule that has an extra proton bound to it; H3O+, commonly represented as H+

base

a substance that reduces the hydrogen ion concentration of a solution

acid

a substance that increases the hydrogen ion concentration of a solution

buffer

a solution that contains a weak acid and its corresponding base, A BLANK minimizes changes in pH when acids or bases are added to the solution

ocean acidification

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

organic chemistry

the study of carbon compounds (organic compounds)

hydrocarbons

an organic molecule consisting only of carbon and hydrogen

isomers

one of several compounds with the same molecular formula but different structures and therefore different properties.

structural isomers

one of several compounds that have the same molecular formula but differ in the covalent arrangements of their atoms

cis-trans isomers

one of several compounds that have the same molecular formula and covalent bonds between atoms but differ in the

spatial arrangements of their atoms

enantiomers

one of two compounds that are mirror images of each other and that differ in shape due to the presence of an asymmetric carbon

functional groups

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

adenosine triphosphate ATP

an adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells

macromolecules

a giant molecule formed by the joining of smaller molecules, usually by a dehydration reaction. Polysaccharides, proteins, and nucleic acids are BLANK

polymer

a long molecule consisting of many similar or identical monomers linked together by covalent bonds

enzymes

a macromolecule serving as a catalyst, a chemical agent that increases that rate of a reaction without being consumed by the reaction. Most BLANK are proteins

monomers

the subunit that serves as the building block of a polymer

dehydration reaction

a chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule

hydrolysis

a chemical reaction that breaks bonds between two molecules by the addition of water; functions in disassembly of polymers to monomers

monosaccharides

the simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides. Also called simple sugars, BLANK have molecular formula that are generally some multiple of CH2O

disaccharide

a double sugar, consisting of two monosaccharides joined by a glucosidic linkage formed by a dehydration reaction

glycosidic linkage

a covalent bond formed between two monosaccharides by a dehydration reaction

polysaccharides

a polymer of many monosaccharides, formed by dehydration reactions

starch

a storage polysaccharides in plants, consisting entirely of glucose monomers joined by a glycosidic linkages

glycogen

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

cellulose

a structural polysaccharide of plant cell walls, consisting of glucose monomers joined by a glycosidic linkage

chitin

a structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods

fat

a lipid consisting of three fatty acids linked to one glycerol molecule' also called a triacylglycerol or triglyceride

fatty acid

a carboxylic acid with a long carbon chain. BLANK vary in length and in the number and location of double bonds' three BLANKS linked to a glycerol molecule form a fat molecule, also called triacylglycerol or triglycerol

triacylglycerol

a lipid consisting of three fatty acids linked to one glycerol molecule; also called a fat or triglyceride

saturated fatty acid

a fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that are affected to the carbon skeleton