Biology Ch 2 Life's Chemical Basis

Front 1

atom

Back 1

particle that is a fundamental building block of all matter

Front 2

atomic number

Back 2

number of protons in the atomic nucleus; determines the element

Front 3

charge

Back 3

electrical property. Opposite charges attract, and like charges repel

Front 4

electron

Back 4

negatively charged subatomic particle that occupies orbitals around an atomic nucleus

Front 5

element

Back 5

a pure substance that consists only of atoms with the same number of protons

Front 6

isotopes

Back 6

forms of an element that differ in the number of neutrons their atoms carry

Front 7

mass number

Back 7

total number of protons and neutrons in the nucleus of and element's atoms

Front 8

neutron

Back 8

uncharged subatomic particle in the atomic nucleus

Front 9

nucleus

Back 9

core of an atom; occupied by protons and neutrons

Front 10

periodic table

Back 10

tabular arrangement of the elements by atomic number

Front 11

proton

Back 11

positively charged subatomic particle that occurs in the nucleus of all atoms

Front 12

radioactive decay

Back 12

process by which atoms of a radioisotope emit energy and/or subatomic particles when their nucleus spontaneously disintegrates

Front 13

radioisotope

Back 13

isotope with an unstable nucleus

Front 14

tracer

Back 14

substance with a detectable component, such as a molecule labeled with a radioisotope

Front 15

free radical

Back 15

atom with an unpaired electron

Front 16

ion

Back 16

atom that carries a charge because it has an unequal number of protons and electrons

Front 17

shell model

Back 17

model of electron distribution in an atom

Front 18

chemical bond

Back 18

an attractive force that arises between two atoms when their electrons interact

Front 19

compound

Back 19

molecule that has atoms of more than one element

Front 20

covalent bond

Back 20

chemical bond in which two atoms share a pair of electrons

Front 21

electronegativity

Back 21

measure of the ability of an atom to pull electrons away from other atoms

Front 22

ionic bond

Back 22

chemical bond that consists of a strong mutual attraction between ion of opposite charge

Front 23

molecule

Back 23

group of two or more atoms joined by chemical bonds

Front 24

polarity

Back 24

separation of charge into positive and negative regions

Front 25

cohesion

Back 25

property of a substance that arises from the tendency of its molecules to resist separating from one another

Front 26

evaporation

Back 26

transition of a liquid to a gas

Front 27

hydrogen bond

Back 27

attraction between a covalently bonded hydrogen atom and another atom taking part in a separate covalent bond

Front 28

hydrophilic

Back 28

describes a substance that dissolves easily in water

Front 29

hydrophobic

Back 29

describes a substance that resists dissolving in water

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mixture

Back 30

an intermingling of two or more types of molecules

Front 31

salt

Back 31

ionic compound that releases ions other that H+ and OH- when it dissolves in water

Front 32

solute

Back 32

a dissolved substance

Front 33

solution

Back 33

homogeneous mixture

Front 34

solvent

Back 34

substance that can dissolve other substances

Front 35

temperature

Back 35

measure of molecular motion

Front 36

acid

Back 36

substance that releases hydrogen ions in water

Front 37

base

Back 37

substance that accepts hydrogen ions in water

Front 38

buffer system

Back 38

set of chemicals that can keep the pH of a solution stable by alternately donating and accepting ions that contribute to pH

Front 39

concentration

Back 39

the number of molecules or ions per unit volume of a solution

Front 40

pH

Back 40

a measure of the number of hydrogen ions in a fluid