Chapter 2 Biology Terms

Front 1

matter

Back 1

anything that occupys space and has mass.

Front 2

elements

Back 2

a substance that cannot be broken down to other substances by other ordinary chemical means.

Hint 2

chemist recognized 92 of these occuring in nature;
Ex: gold, copper, and oxygen

Front 3

trace elements

Back 3

listed at the bottom of the perodic table are essential by only in minute quantities.

Hint 3

examples: Fe, and I

Front 4

Elements that make up 96% of the human body:

Back 4

oxygen, hydrogen, carbon and nitrogen

Hint 4

main indegrience of molecules such as protiens, sugars, and fats

Front 5

Accout for the remaining 4% of the body:

Back 5

phosphorus, calcium, potassium, sulfur, sodium, chlorine and magnesium

Hint 5

involved in important functions such as bone formation, nerve signaling, and DNA synthesis

Front 6

compound

Back 6

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

Hint 6

example: NaCl,H2O

Front 7

atom

Back 7

named from a Greek word meaning "indivisible;" is the smallest unit of matter that still retains the properties of an element

Front 8

proton

Back 8

subatomic particle with a single postive electrical charge

Front 9

electron

Back 9

subatomic particle with a single negative electrical charge

Front 10

neutron

Back 10

electrically neutral; no charge

Front 11

nucleus

Back 11

atoms central core, containing protons and neutrons

Front 12

atomic number

Back 12

equal to the number of protons that are in a nuclues

Front 13

mass number

Back 13

the sum of the protons and neutrons in a nucleus

Front 14

atomic mass

Back 14

equal to the mass number

Front 15

isotopes

Back 15

elements that has the same number of protons and electrons and behave idenically in chemical reactions but have a different number of neutrons

Front 16

radioactive isotope

Back 16

an isotope, in which the nuclues decays spontaneously, giving off particles and energy

Front 17

electron shells

Back 17

energy levels in which the electrons fall; depending on its atomic number it may have 1, 2 or more surround the nucleus

Front 18

chemical bonds

Back 18

interactions in which atoms stay closer together

Front 19

ion

Back 19

an atom or molecule with an electrical charge resulting from a gain or loss of one or more electrons

Front 20

ionic bond

Back 20

two ions with opposite charges that attract each other that hold the ions together

Front 21

salt

Back 21

a synonym for an ionic compound

Hint 21

example: sodium cholride

Front 22

covalent bond

Back 22

second kind of strong chemical bond in which two atoms share one or more pairs of outer shell electrons

Front 23

molecule

Back 23

formed when two or more atoms are held together by covalent bonds

Front 24

double bond

Back 24

when two or more atoms share to pairs of electrons and its indicated by a pair of lines

Front 25

electronegativity

Back 25

an atoms attractions for shared electrons

Front 26

nonpolar covalent bond

Back 26

when electrons are shared equally between the atoms

Front 27

polar covalent bond

Back 27

unequal sharing of the electrons between the atoms

Front 28

polar molecule

Back 28

unequal distribution of charges

Hint 28

example: water

Front 29

hydrogen bond

Back 29

a postively charged region in this special type of bond is always a hydrogen bond

Front 30

cohesion

Back 30

the tendency of molecules to stick together

Hint 30

stonger for water that for more other liquids

Front 31

adhesion

Back 31

the clinging of one substance to another

Front 32

surface tension

Back 32

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

Front 33

heat

Back 33

the amount of energy associated with the movement of atoms and molecules in a body of matter

Front 34

temperature

Back 34

mesures the intensity of heat or the average speed of molecules rather than the total amount of heat energy in a body of matter

Front 35

solution

Back 35

a liquid consisting of a uniform mixture or two of more substances

Front 36

solvent

Back 36

the dissolving agent

Front 37

solute

Back 37

the substance that is dissolved

Front 38

aqueous solution

Back 38

when water is the solvent

Front 39

acid

Back 39

a compound that donates hydrogen ions to solutions

Hint 39

example: hydrochloric acid

Front 40

base

Back 40

a compound that accepts hydrogen ions and removes them from the solution

Hint 40

example: sodium hydroxide

Front 41

pH scale

Back 41

describes how acidic or basic a solution is

Hint 41

scale ranges 0, being most acidic, to 14, being most basic

Front 42

buffers

Back 42

substances that minimize changes in pH, they do so by accepting H+, when it is excess and donating H+ when it is depleted

Front 43

acid preceptation

Back 43

rain, snow or fog with a pH lower than 5.6

Front 44

chemical reaction

Back 44

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

Front 45

reactants

Back 45

when the arrow indicated the conversion of the starting materials

Front 46

product

Back 46

the resulting materials indicated by the arrow