Campbell Biology Chapter 2 Vocabulary

Front 1

matter

Back 1

anything that takes up space and has mass

Front 2

element

Back 2

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

Front 3

compound

Back 3

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

Front 4

essential elements

Back 4

20 to 25% of the 92 elements essential to healthy life

Front 5

trace elements

Back 5

required by an organism in only minute quantities

Front 6

atom

Back 6

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

Front 7

neutrons

Back 7

neutral charge, in the nucleus, mass of 1

Front 8

protons

Back 8

positive charge, in the nucleus, mass of 1

Front 9

electrons

Back 9

negative charge, in the electron cloud, mass of 0

Front 10

atomic nucleus

Back 10

center of atom, contains protons and neutrons

Front 11

atomic number

Back 11

number of protons

Front 12

mass number or atomic mass

Back 12

neutrons + protons

Front 13

isotopes

Back 13

same atom different number of neutrons

Front 14

radioactive isotopes

Back 14

nucleus decays spontaneously, or the nucleus has the tendency to lose particles, unstable

Front 15

energy

Back 15

capacity to change

Front 16

potential energy

Back 16

energy matter possesses because of location and structure, most common in the form of chemical energy

Front 17

electron shells

Back 17

levels of energy at different distances from the nucleus

Front 18

valence electrons

Back 18

outer electrons

Front 19

valence shell

Back 19

outermost shell

Front 20

orbital

Back 20

dimension in space where an electron can be found 90% of the time

Front 21

chemical bonds

Back 21

attractions that hold atoms close together

Front 22

covalent bond

Back 22

sharing a pair of valence electrons by two atoms

Front 23

molecule

Back 23

two or more atoms of the same type held together by covalent bonds

Front 24

single or double bonds

Back 24

sharing one or two electrons at a time

Front 25

valence

Back 25

bonding capacity, usually equals the number of unpaired electrons required to complete the atom’s outermost shell

Front 26

electronegativity

Back 26

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

Front 27

nonpolar covalent bond

Back 27

electrons are shared equally

Front 28

polar covalent bond

Back 28

electrons are not shared equally

Front 29

ion

Back 29

charged atom or molecule (not neutral)

Front 30

cation

Back 30

positively charged ion

Front 31

anion

Back 31

negatively charged ion

Front 32

ionic bond

Back 32

cations and anions are attracted to each other

Front 33

ionic compounds or salts

Back 33

compounds formed by ionic bonds

Front 34

hydrogen bond

Back 34

when partially positively charged hydrogen is bonded to an electronegative atom the hydrogen is attracted to a different electronegative atom nearby

Front 35

van der waals interactions

Back 35

this can occur in both polar and nonpolar bonds, atoms are not arranged symmetrically so there are regions of positive or negative charge that enable all atoms and molecules to stick to one another

Front 36

chemical reactions

Back 36

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

Front 37

reactants

Back 37

starting materials of a chemical reactions

Front 38

products

Back 38

what you get out of a chemical reaction

Front 39

chemical equilibrium

Back 39

forward and reverse reactions occur at the same rate, there can be change but ultimately they are balanced

Front 40

strongest bonds

Back 40

covalent bonds and iconic bonds