Chapter 2 - Chemical Bonding

Question 1

Bonding

Answer 1

bond = forces of attraction balanced against forces of repulsion (nuclei to nuclei), connects atoms together in some matter, long term
chemical bond = force within a fundamental particle, covalent or ionic
physical bond = force between fundamental particles

Question 2

Bond types

Answer 2

covalent = EN between 0 and 0.4, both ends of the bond are neutral
polar covalent = EN between 0.4 and 1.7 (approximately), bond has partial positive and negative ends
ionic = EN greater than 1.7 (approximately), metal and a nonmetal, high melting point, hard, brittle

Question 3

Ionic bonding

Answer 3

electrostatic attraction between oppositely charged ions (charged atoms)
ionization = gain/loss of electrons to/from other atoms
ionic bond formation = the attraction due to ionization

Question 4

Ionic substances and electricity

Answer 4

ionic substances are not conductive in a solid state due to the organized arrangement of ions in a crystal lattice shape
they are conductive in a dissolved, liquid, or gas state due to the motion of charges which produce an electrical current
the ions of a substance do not experience attraction in a solution because they are surrounded by hydration spheres

Question 5

Formula for ionic substances

Answer 5

ionization process (transfer of electrons) determines the charge of the ions
the criss-cross method determines the resulting ratio of the ions to form a substance
go to lowest terms, as this is only a ratio

Question 6

Covalent bonding

Answer 6

shared pair of electrons, mutual attraction between nuclei and shared electrons
when all atoms have a full valence shell, no more sharing is needed, unless in the case of a free radical or boron and beryllium
when deriving a formula, you cannot go to lowest terms because the substances exhibit different properties
covalent connection can be single bonded, double bonded, or triple bonded

Question 7

Molecular structure diagram

Answer 7

formula displays the number of atoms of each element in the molecule
expanded formula displays which atom is connected to which, which helps to distinguish the difference between compounds with the same formula
a molecular structure diagram can then be created from an expanded formula

Question 8

Forces on particles

Answer 8

there are always attractive forces between fundamental particles in substances
intramolecular forces = holds atoms of a molecule together, affect chemical properties (covalent)
intermolecular forces = attract adjacent molecules together due to oppositely charged poles, affect physical properties (ionic)
types of covalent bonds and geometry of the bonds determine the intermolecular forces, and therefore determine physical properties

Question 9

Bond angles

Answer 9

bond angles are determined by the number of lone pairs and bonds
bonds and lone pairs are mutually repulsive, lone pairs more so than bonds, and therefore adopt the maximum angle between bonds
in a 2D drawing, it may appear as if there are several versions of molecules, however in a 3D version, there is one molecule due to bond angles

Question 10

Shape names

Answer 10

straight = AX2E0
bent = AX2E2, AX2E1
flat triangle = AX3E0
triangular pyramid = AX3E1
tetrahedral = AX4E0

Question 11

Determining polarity

Answer 11

are any of the bonds polar (yes = continue, no = non)
is the shape symmetrical (yes = continue, no = polar)
are all the bonds the same (yes = non, no = polar)

Question 12

Dipole-dipole forces

Answer 12

dipole = structure with two pole

attractive force acting between polar molecules, positive end of one is attracted to the negative end of another

Question 13

London dispersion forces

Answer 13

electrostatic forces of attraction between adjacent molecules due to temporary dipoles created by random motion of electrons
affected by number of electrons in the molecule

Question 14

Hydrogen bonding

Answer 14

not a function of electron dispersion
attraction between hydrogen proton and nearby lone pairs on other molecules (oxygen, fluorine, nitrogen)
forms a very strong intermolecular force
mutual attraction of 2 electron pairs for the same nucleus, inverse covalent bond
10% as strong as a covalent bond

Question 15

Ranking of forces

Answer 15

ionic bonds
hydrogen bonds
dipole-dipole
London dispersion forces

Question 16

Physical properties related to bonds

Answer 16

the stronger the intermolecular bonds, the more energy must be used to break them, thermal energy is required
hardness = must separate the molecules
malleability = state of spatial organization in intermolecular bonds
odour = inversely related to intermolecular bond strength
melting point = directly related in intermolecular bond strength

Question 17

Solubility

Answer 17

solution = homogeneous mixture, same properties all the way down to particle size
polar molecules dissolve in polar
non polar dissolves in non polar
ionic can dissolve in polar depending on the charges

Question 18

Nomenclature

Answer 18

naming of pure substances = one substance has one name
naming of molecular substances = one structure has one name
regulated by IUPAC

Question 19

Ionic nomenclature

Answer 19

binary ionic compound = cation (roman numeral) anion
elements that require roman numerals = copper, tin, lead, iron
cation = name of element or of polyatomic ion, positive
anion = name of polyatomic ion, or of element, change ending to “ide”, negative
eg. copper (II) chloride

Question 20

Molecular nomenclature

Answer 20

list of element names, change ending to “ide”
inorganic molecules = order of the periodic table
organic molecules = alphabetical order
use greek prefixes to indicate number of atoms in formula

Question 21

Prefixes

Answer 21

mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca
omit prefix “mono” always for the first name in the list, or when ambiguity is not created
eg. carbon monoxide vs carbon dioxide

Question 22

Acid nomenclature

Answer 22

named as if ionic with hydrogen as the cation

eg. aqueous hydrogen sulfate, aqueous hydrogen chloride

Question 23

Coordinate covalent bonds

Answer 23

coordinate covalent bond = covalent bond made from a lone pair, once made, they are no different from a non coordinate bond

Question 24

Physical vs. chemical

Answer 24

physical change = any change not producing a new substance
chemical change = any process that produces a new substance
physical property = a trait that helps identify a substance
chemical property = description how a substance interacts with other substances in chemical changes

Question 25

Types of substances

Answer 25

pure substance = only one type of particle, cannot be broken down into other substances by physical processes
element = pure substance with only one type of atom, cannot be physically or chemically broken down
compound = pure substance with more than one type of atom, more than one element, can be chemically broken down

Question 26

Types of mixtures

Answer 26

mechanical mixture = a non-uniform mixture, different characteristics in different regions
homogenous mixture = uniform mixture, a solution