CHEM 105 Chapter 4 Quiz

Question 1

ionic bonding is between

Answer 1

a metal and a nonmetal

Question 2

covalent bonding is between

Answer 2

nonmetals

Question 3

ionic bonds involve

Answer 3

the transfer of electrons from one atom to the other (the metal atom becomes the cation (loses e-) and the nonmetal atom becomes the anion (gains e-))

Question 4

the result of ionic bonding is

Answer 4

an ionic compound, which in the solid phase is composed of a lattice

Question 5

covalent bonds involve

Answer 5

the sharing of electrons between two atoms

Question 6

a compound is represented by its

Answer 6

chemical formula, the type and number of each element present in the compound

Question 7

types of chemical formulas

Answer 7

empirical, molecular, structural

Question 8

empirical formula

Answer 8

gives the relative number of atoms of each element in a compound; the simplest whole number (ratio) representation of the type and number of elements present in a molecule

Question 9

molecular formula

Answer 9

gives the actual number of atoms of each element in a molecule of a compound

Question 10

the molecular formula (can/cannot) be the same as an element’s empirical formula

Answer 10

can

Question 11

structural formula

Answer 11

a sketch or diagram of how the atoms in the molecule are bonded to each other; it uses lines to represent covalent bonds

Question 12

Lewis structure model

Answer 12

represents an element’s valence electrons as dots

Question 13

Why does the Lewis structure focus on valence electrons?

Answer 13

chemical bonding involves the transfer or sharing of valence electrons between two or more atoms

Question 14

“Octet Rule”

Answer 14

when atoms bond, they tend to gain, lose, or share e-s to result in a noble gas-like configuration

Question 15

lattice energy

Answer 15

the extra stability that accompanies the formation of the crystal lattice; the energy released when the solid crystal forms form separate ions in the gas state; depends on size of charges and inversely on distance b/w ions

Question 16

ionic compounds can be categorized into two types

Answer 16

1. metal forms only one type of ion

2. metal forms more than one type of ion

Question 17

naming binary ionic compounds of type I cations

Answer 17

[name of cation] + [base name of anion (+ -ide)]

Question 18

naming type II binary ionic compounds

Answer 18

[name of cation] + (charge of cation in roman numerals) + [base name of anion (+ -ide)]

Question 19

oxyanions

Answer 19

anions containing oxygen and another element

Question 20

naming oxyanions

Answer 20

according to the number of oxygen atoms in the ion

if there are two ions in the series, the one with MORE oxygen atoms has the ending -ate and the one with LESS oxygen atoms has the ending -ite

if there are more than two ions in the series, then the prefixed hypo- (less than) and per- (more than) are used (e.g. hypo-?-ite, ?-ite, ?-ate, per-?-ate)

Question 21

naming ionic compounds containing polyatomic ions

Answer 21

named in the same manner as binary ionic compounds, except the name of the polyatomic ion is used (e.g. NaNO2 is sodium nitrite)

Question 22

hydrated ionic compounds

Answer 22

hydrates are ionic compounds containing a specific number of water molecules associated with each formula unit (e.g. MgSO4 * 7 H2O is magnesium sulfate heptahydrate)

Question 23

common hydrate prefixes

Answer 23

hemi 1/2
mono 1
di 2
tri 3
tetra 4
penta 5
hexa 6
hepta 7
octa 8

Question 24

covalent bonding: bonding pairs

Answer 24

electrons that are shared by atoms

Question 25

covalent bonding: lone pairs

Answer 25

electrons that are not shared by atoms but belong to a particular atom (AKA nonbonding pairs)

Question 26

single covalent bonds

Answer 26

when two atoms share one pair of electrons

Question 27

double covalent bond

Answer 27

when two atoms share two pairs of electrons

Question 28

triple covalent bond

Answer 28

when two atoms share three pairs of electrons

Question 29

the formula for a molecular compound (can/cannot) be readily determined from its constituent elements because ?

Answer 29

cannot; the same combination of elements may form different molecular compounds, each with a different formula (e.g. Nitrogen and Oxygen form NO, NO2, N2O, N2O3, etc.)

Question 30

molecular compounds

Answer 30

composed of two or more nonmetals

Question 31

naming molecular compounds

Answer 31

1. write the name of the element with the smallest group number first (if the two elements lie in the same group, then write the element with the greatest row number first) 2. the prefixes given to each element indicate the number of atoms present [(prefix) + (name of 1st element)] + [(prefix) + (base name of 2nd element + -ide)]

Question 32

prefixes for molecular compounds (same as hydrates)

Answer 32

``` mono 1 (usually omitted) di 2 tri 3 tetra 4 penta 5 hexa 6 hepta 7 octa 8 nona 9 deca 10 ```

Question 33

molecular mass

Answer 33

the mass of an individual molecule or formula unit; the mass of one mole of that compound

Question 34

determining a compound's molecular mass

Answer 34

sum of the masses of the atoms in a single molecule or formula unit

Question 35

the percentage of each element in a compound can be determined from

Answer 35

1. the formula of the compound 2. the experimental mass analysis of the compound % mass of element Z = [(molecular mass of element Z) / (mass of 1 mol of compound)] x 100%

Question 36

how to determine a chemical formula from experimental data

Answer 36

elemental analysis: masses of elements formed when a compound is decomposed, or that react together to form a compound (combustion analysis); percent composition

Question 37

finding an empirical formula

Answer 37

1. convert the percentage to grams 2. convert mass (g) to moles 3. divide all by the smallest number of moles to obtain the atom-to-atom ratio for each of the elements in the compound 4. multiply all mole ratios by a number to make all whole numbers

Question 38

to determine the molecular formula for a compound given the empirical formula,

Answer 38

molecular formula = (empirical formula) * n n = (molar mass) / (empirical formula molar mass)

Question 39

combustion analysis

Answer 39

a common technique for analyzing compounds is to burn a known mass of compound and weight the amount of product made; by knowing the m ass of the product and composition of constituent element in the product, the original amount of constituent element can be determined

Question 40

early chemists divided compounds into two types

Answer 40

organic and inorganic

Question 41

organic compounds

Answer 41

compounds from living things; easily decomposed, cannot be made in lab

Question 42

inorganic compounds

Answer 42

compounds from the nonliving environment; very difficult to decompose but able to be synthesized

Question 43

organic compounds are mainly made of

Answer 43

C and H, sometimes with O, N, P, and S

Question 44

the main element that is the focus of organic chemistry is

Answer 44

carbon

Question 45

carbon bonding

Answer 45

carbon atoms bond almost exclusively covalently; when carbon bonds, it forms four covalent bonds; unique b/c can form limitless chains of C atoms, both straight and branched, and rings of C atoms