Chapter 2

Question 1

electrons

Answer 1

negligible mass; negative charge

Question 2

protons

Answer 2

have mass; positive charge

Question 3

neutrons

Answer 3

have mass; no charge

Question 4

1 dalton

Answer 4

1.7x10^-24

Question 5

element

Answer 5

a fundamental substance containing only one kind of atom

Question 6

atomic number

Answer 6

number of protons

Question 7

mass number

Answer 7

protons + neutrons

Question 8

isotopes

Answer 8

forms of an element with different numbers of neutrons, thus different mass numbers

Question 9

molecule

Answer 9

a stable association of atoms

Question 10

orbital

Answer 10

regions where an electron is found 90% of the time

Question 11

electron shell

Answer 11

a specific sequence inside orbitals; also called energy levels

Question 12

first electron shell

Answer 12

1 orbital; holds 2 electrons

Question 13

second electron shell

Answer 13

4 orbitals; holds 8 electrons

Question 14

third electron shell

Answer 14

4 orbitals; holds 8 electrons

Question 15

valence shell

Answer 15

determines how the atom behaves; the outermost electron shell

Question 16

chemical bonds

Answer 16

attractive force that links atoms together to form molecules

Question 17

covalent bonds

Answer 17

atoms share one or more pairs of electrons so that the outer shells are filled; very strong

Question 18

electronegativity

Answer 18

attractive force that an atomic nucleus exerts on electrons

Question 19

nonpolar covalent bonds

Answer 19

electrons are shared equally (atoms have similar electronegativity)

Question 20

polar covalent bonds

Answer 20

one atom has greater electronegativity, so electrons are drawn more to that nucleus

Question 21

ionic bonds

Answer 21

when one atom is much more electronegativity than the other, a complete transfer of electrons may occur; formed by electrical attraction of positive and negative ions

Question 22

ions

Answer 22

electrically charged particles formed when atoms lose or gain one or more electrons

Question 23

cations

Answer 23

positive

Question 24

anions

Answer 24

negative

Question 25

hydrogen bonds

Answer 25

attraction between the - end of one molecule and the + hydrogen end of another molecule

Question 26

hydrophilic

Answer 26

polar molecules that form hydrogen bonds with water; water loving

Question 27

hydrophobic

Answer 27

nonpolar molecules, such as hydrocarbon; water hating

Question 28

van der waals forces

Answer 28

attractions between nonpolar molecules that are close together; brief and weak