Chapter 2: The Chemical Basis Of Life

Front 1

acid

Back 1

substances that dissociate in water; releasing hydrogen ions (H+)

Front 2

atom

Back 2

smallest particle of an element

Front 3

atomic mass

Back 3

constant weight of an atom; protons plus neutrons

Front 4

atomic number

Back 4

determined by the number of protons in an atom; equals number of electrons when an atom is neutral

Front 5

atomic symbol

Back 5

name of an element & it's atoms; represented by one or two letters

Hint 5

Na

Front 6

base

Back 6

substances that either take up hydrogen ions or release hydroxide ions

Front 7

buffer

Back 7

chemical or combination of chemicals that keep pH in its normal limits

Front 8

compound

Back 8

molecule containing atoms of more than one element

Front 9

covalent bond

Back 9

when two atoms share electrons in order to have a completed outer shell

Front 10

electron

Back 10

negative charge in an atom

Front 11

electronegativity

Back 11

affinity for electrons in a covalent bond; larger atoms - higher affinity, smaller atoms - lower affinity

Front 12

electron shell

Back 12

energy levels in an atom

Front 13

first shell

Back 13

complete with two electrons

Front 14

other shells

Back 14

complete with eight electrons, assuming an atomic number of 20 or below

Front 15

element

Back 15

substance that can't be broken down into another substance

Front 16

hydrogen (H) bond

Back 16

positive hydrogen atoms in one molecule are attracted to the negative oxygen atoms in other water molecules

Front 17

hydrophilic

Back 17

molecules are attracted to water

Front 18

hydrophobic

Back 18

molecules are not attracted to water

Front 19

ion

Back 19

charged atoms

Front 20

ionic bonds

Back 20

when two atoms are held together by the attraction between opposite charges

Front 21

isotope

Back 21

atoms of the same element that differ in number of neutrons

Front 22

matter

Back 22

anything that takes up space and has weight

Front 23

molecule

Back 23

group of atoms bonded together

Front 24

neutron

Back 24

no electric charge

Front 25

nucleus

Back 25

center of an atom; containing a neutron and a proton

Front 26

octet rule

Back 26

atoms react with one another in order to have a completed outer shell with eight electrons

Front 27

pH

Back 27

mathematical way of indicating number of hydrogen ions in a solution

Front 28

pH scale

Back 28

indicates acidity or basicity of a solution

Front 29

polar

Back 29

atoms on both sides of the bond are partially charged, although overall molecule itself bears no net charge

Front 30

product

Back 30

molecules formed by a reaction

Front 31

proton

Back 31

positive charge in an atom

Front 32

reactant

Back 32

molecules that participate in a reaction

Front 33

salt

Back 33

compound produced by reaction between an acid and a base

Front 34

hydrogen ion (H+)

Back 34

hydrogen atom that has lost its electron and bears a positive charge

Front 35

tracer

Back 35

substance having an attached radioactive isotope that allows a researcher to track it's whereabouts in a biological system

Front 36

valence shell

Back 36

number of electrons in outer shell; determines reactivity of an atom