Chapter 4 Vocab Biology

Front 1

matter

Back 1

anything that occupies space and has mass

Front 2

element

Back 2

a pure substance that cannot be broken down into other substances by chemical means

Front 3

trace element

Back 3

elements that make up less than 0.01 percent of your body mass, are nevertheless critical to your health

Front 4

compound

Back 4

a substance containing two or more elements that are chemically combined in a fixed ratio

Front 5

atom

Back 5

the smallest possible particle of an element

Front 6

proton

Back 6

a subatomic particle with a single unit of positive electrical charge

Front 7

electron

Back 7

a subatomic particle with a single unit of negative electrical charge

Front 8

neutron

Back 8

electrically neutral

Front 9

nucleus

Back 9

in an atom, the central core that contains protons and neutrons

Front 10

atomic number

Back 10

number of protons in an atom's nucleus; is unique for each element

Front 11

isotope

Back 11

one of several forms of an element, each containing the same number of protons in their atoms but a different number of neutrons

Front 12

radioactive isotope

Back 12

isotope in which the nucleus decays (breaks down) over time, giving off radiation in the form of matter and energy

Front 13

ionic bond

Back 13

chemical bond that occurs when an atom transfers an electron to another atom

Front 14

ion

Back 14

atom that has become electrically charged as a result of gaining or losing an electron

Front 15

covalent bond

Back 15

chemical bond that forms when two atoms share electrons

Front 16

molecule

Back 16

two or more atoms held together by covalent bonds

Front 17

chemical reaction

Back 17

breaking of old and formation of new chemical bonds that result in new substances

Front 18

reactant

Back 18

starting material for a chemical reaction

Front 19

product

Back 19

material created as a result of a chemical reaction

Front 20

polar molecule

Back 20

molecule in which opposite ends have opposite electric charges

Front 21

hydrogen bond

Back 21

bond created by the weak attraction of a slightly positive hydrogen atom to a slightly negative portion of another molecule

Front 22

cohesion

Back 22

tendency of molecules of the same kind to stick to one another

Front 23

thermal energy

Back 23

total amount of energy associated with the random movement of atoms and molecules in a sample of matter

Front 24

temperature

Back 24

measure of the average energy of random motion of particles in a substance

Front 25

solution

Back 25

uniform mixture of two or more substances

Front 26

solvent

Back 26

substance in a solution that dissolves the other substance and is present in the greater amount

Front 27

solute

Back 27

substance in a solution that is dissolved and is present in a lesser amount

Front 28

aqueous solution

Back 28

solution in which water is the solvent

Front 29

acid

Back 29

compound that donates H+ ions to an aqueous solution and measures less than 7 on the pH scale

Front 30

base

Back 30

compound that removes H+ ions from an aqueous solution and that measures more than 7 on the pH scale

Front 31

pH scale

Back 31

a range of numbers used to describe how acidic or basic a solution is; ranges from 0 (most acidic) to 14 (most basic)

Front 32

buffer

Back 32

substance that maintains a fairly constant pH in a solution by accepting H+ ions when their levels rise and donating H+ ions when their levels fall