Unit 3: Compounds

Question 1

formula unit

Answer 1

The smallest whole-number ratio of the ions in the ionic compound lattice

Ratio rather than single particle (as in a molecule)

Question 2

naming molecular compounds (for binary)

Answer 2

1. Greek prefix for # of atoms (drop if only 1)
2. Element 1 name (furthest down, to left)
3. Greek prefix for # of atoms
4. Element 2 name
5. Suffix “-ide”

EX:

NO Nitrogen Monoxide

N₂O₃ Dinitrogen Trioxide

Question 3

nonelectrolyte

Answer 3

Compound does not generate ions when dissolved in water

Nonelectrolyte solutions (e.g. sugar dissolved in water) do not conduct electricity

Question 4

What are the Greek prefixes for molecular compounds?

Answer 4

# of Atoms__Prefix 1 mono- 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta- 8 octa- 9 nona- 10 deca-

Question 5

oxyanions

Answer 5

Negatively charged nonmetal atoms surrounded by 1-4 oxygen atoms

Question 6

organic compound

Answer 6

Molecules with carbon

Question 7

polyatomic ion nomenclature

Answer 7

Between 2 & 5 atoms sharing a single charge (nearly all are negatively charged)

Many are oxyanions and usually remain together during chemical reactions

• Nonmetal elements that form only one oxyanion use suffix “-ate”.
  
  • EX: BO₂^2- borate
• Nonmetal elements that form 2 oxyanions use the suffix “-ate” for the one with more oxygen atoms and “-ite” for the one with less
  
  • EX: SO₄^2- sulfate
  • SO₃^2- sulfite
• Nonmetal elements that form 4 oxyanions use the prefix “per-“ or “hypo-“ as well as the suffix “-ate” or “-‘ite”
  
  • EX: ClO₄^- perchlorate
  • ClO₃^- chlorate
  • ClO₂^- chlorite
  • Cl0^- hypochlorite

Question 8

How can you identify an inorganic compound?

Answer 8

Molecules without carbon

Inorganic compounds can be classified further as either ionic or molecular

Question 9

What are the composition and properties of an ionic compound?

Answer 9

Made of ions, usually a metal cation and non-metal anion; neutral - all charges are balanced

Form lattices - 3D array of ions

Properties

• crystalline solid
• hard, brittle
• very high melting point
• very high boiling point
• high density
• strong electrolyte in aqueous solution
• electrical conductivity good when compound is molten

Question 10

ionic compound nomenclature

Answer 10

The name of the cation followed by the name of the anion

If the compound includes a transition metal cation then include a roman numeral in parenthesis for the charge

Don’t indicate the number of each ion (when saying or writing out longhand)

Question 11

ionize

Answer 11

The process by which a compound dissolves in water to produce ions

AKA dissociation

Question 12

acid nomenclature

Answer 12

Name of an acid depends on the name of the anion it contains

Acids with monoatomic anions: root name of element w/ prefix “hydro-“ and suffic “-ic acid” EX: HCl Hydrochloric Acid

Acids with polyatomic anions: use the suffix “-ic acid” or “-ous acid” (memory trick: acid naming disease; ate-ic, ite-ous … if the ion ended in ate, the acid ends in ic, etc)

Question 13

molar mass

Answer 13

The mass (in grams) of 1 mole of a substance

AKA molecular weight or formula weight

The sum of the atomic masses of its elements - mass (in grams) of 1 mole of the compound (g/mol)

Used to convert between the mass of a compound (in units of grams) and the amount of a compound (in units of moles)

Common to report with 2 decimal places

Question 14

acids

Answer 14

Class of compounds that produce hydrogen ions - H⁺ - when they are dissolved in water

Most acids are molecular compounds that ionize in water

HX(g) → H⁺(aq) + X^-(aq)

HX(g) + H₂O(l) → H₃O⁺(aq) + X^-(aq)

Strong acids ionize or dissociate completely in water

Question 15

bases

Answer 15

Class of compounds that produce hydroxide ions - OH^- - when they are dissolved in water

Most bases are ionic compounds that contain hydroxide ions; ammonia is an important exception

MOH(s) → M⁺(aq) + OH^-(aq)

NH₃(g) + H₂O(l) → NH₄⁺(aq) + OH^-(aq)

Strong bases ionize or dissociate completely in water

Question 16

electrolyte

Answer 16

Compound that generates ions when dissolved in water

• strong: fully dissociated in water (EX: NaCl)
• weak: not fully dissociated in water

Electrolyte solutions conduct electricity - strong are better conductors then weak

Question 17

convert from moles to particles

Answer 17

moles ⇒ Avogadro’s Number ⇒ # of formula units ⇒ chemical formula ⇒ # of atoms or ions

Question 18

convert from moles to mass

Answer 18

moles ⇒ molar mass ⇒ mass in grams

Question 19

What are the composition and properties of a molecular compound?

Answer 19

Contain only nonmetals

Form molecules - small group of atoms that stay together

Properties:

• gas, liquid or solid
• soft solid
• low melting point
• low boiling point
• low density
• weak electrolyte or non-electrolyte in aqueous solution
• electrical conductivity poor in pure form

Question 20

monoatomic ion nomenclature

Answer 20

Simpliest ions, contain only one charged atom

Main group cation: name of the element + “ion”

Main group anion: root name of the element with suffix “-ide ion”

Transition Metal: include charge as roman numeral

EX:

O^2- oxide ion

Na⁺ sodium ion

N^3- nitride ion

FeCl₂ iron (II) chloride

FeCl₃ iron (III) chloride

CuSO₄ copper (II) sulfate