Exam 2

Question 1

Stability of Noble gases

Answer 1

Helium, neon and argon are inert, they undergo few, if any chemical reactions. This results from their electron structures, each has an octet of electrons in its outermost shell.

Question 2

When do elements become less reactive?

Answer 2

when they alter their electron structures to that of a noble gas

Question 3

Isoelectronic

Answer 3

same # of elements.

Question 4

Octet Rule

Answer 4

In chemical reactions, atoms tend to gain, lose or share electrons so as to have eight valence electrons.

Question 5

Ionic bond

Answer 5

Result of 2 opposite charges being attracted to each other

Question 6

Crystal lattice

Answer 6

ionic compounds are held together by ionic bonds and exist as crystal lattice

Question 7

Metals

Answer 7

lose electrons to take on the electron structures of the previous noble gas. They form positive ions (cations)

Question 8

Nonmetals

Answer 8

gain electrons to take on the electron structure of the next noble gas. They become negative ions (anions)

Question 9

Cation charge

Answer 9

the charge of a cation from the representative elements is the same family #
The name of the cation is dimly the name of the element
(Sodium ion)

Question 10

Anion charge

Answer 10

The charge of an anion from the representative element is equal to the family number -8
-the name of the anion is the root name of the element plus the suffix -ide
chloride Ion, Oxide ion.

Question 11

Covalent Bonds

Answer 11

When 2 atoms share a pair of electrons (they don’t lose or gain them)

• generally have molecules that consist of 2 or more nonmetals. (water, ammonia and methane)
• can share two or three pairs of electrons—single, double or triple bonds.

Question 12

Binary Covalent Compounds

Answer 12

Named by using prefix to denote the # of atoms. 
mono 1
Di   2
Tri   3
Tetra   4
Penta   5
Hexa   6
Hepta  7
Octa    8
nona  9
Deca   10

Question 13

Electronegativity

Answer 13

A measure of an atom’s attraction for the pair of electrons in a bond. The atoms to the right on the periodic table are in general more electronegative than the atoms to the left. Tends to be higher @ the top & lower @ the bottoms of the column.

Question 14

Nonpolar covalent bonds

Answer 14

when 2 atoms with the same or similar electronegativity form a bond, the bonding electrons are equally shared between the 2 atoms. Such a bond exhibits a separation of charge and it is called a non polar covalent bond.
< 0.5

Question 15

Polar covalent

Answer 15

When 2 atoms with differing electronegativity form a bond, the bonding electrons are drawn closer to the atoms with the higher electronegativity.
- 0.5 2.0

Question 16

Ionic Bond

Answer 16

> 2.0

Question 17

Bond polarity

Answer 17

The difference in electronegativity between 2 bonded atoms can be used to determine the type of bond.

Question 18

Polyatomic ions

Answer 18

Groups of covalently bonded atoms with a charge.
Group 1: all have +1
Group 2: all have +2
When combined, they have to be neutral

Question 19

Calcium nitrate

Answer 19

Ca+2 NO3- : Ca(NO3)2

Question 20

Ammonium Sulfate

Answer 20

(NH4)+1 SO4 -2

(((NH4)+1)2 SO4-2)0

Question 21

Name Cu (HSO4)2

Answer 21

Copper hydrogen sulfate

Question 22

Reactants

Answer 22

the species present before the reaction

Question 23

Products

Answer 23

the species present after the reaction

Question 24

when talking about products and reactants, what does the arrow mean?

Answer 24

yields or reacts to

Question 25

Coefficients

Answer 25

numbers used to balance a chemical equation. Never change the subscripts.

Question 26

Law of combined volumes

Answer 26

when all measurements are made at the same temp and pressure, the volumes of gaseous reactants & products are in a small whole-number ratios.

Question 27

Avogadro’s hypothesis

Answer 27

when measured at the same temp and pressure, volumes of all gasses contain the same # of molecules.

Question 28

Avogadro’s number

Answer 28

defined as the # of atoms in a 12-g sample of baron -12 and is 6.02x10 to the 23

Question 29

A mole

Answer 29

the amount of a substance that contains 6.02x10 to the 23 particles.

Question 30

Molar volume

Answer 30

one mole of any gas occupies a volume of 22.4 L @ standard temp and pressure (S.T.P)

Question 31

S.T.P

Answer 31

1 atmosphere of pressure and a temp of 0 Celsius

Question 32

Formula mass (mole)

Answer 32

the sum of the atomic masses for all atoms in a formula.

If the formula represents a molecule, often the term MOLECULAR MASS is used.

Question 33

Stoichiometry

Answer 33

the quantitative relationship between reactants and products in a balanced chemical equation the coefficients of a balanced chemical equation represent moles

Question 34

steps in stoichiometric calculation

Answer 34

• write and balance the chemical equation
• determine molar masses of substances involved in the equation
• use the coefficients of the balanced equation to convert the moles of the given substance to the moles of the desired substance.
• use the molar mass to convert the moles of the desired substance to grams of the desired substance