1. Chemical Family Resemblances
TYPES OF COMPOUNDS
Chemical Family Resemblances

2. Binary salts
Binary salts are made of a metal and a nonmetal – only two different elements. Examples: NaCl, MnO2
Binary salts are named with the name of the metal first, then the name of the nonmetal with the “-ide” ending.
Example: K2O
potassium oxide

3. FORMULAS The formula unit is the simplest ratio of ions in the salt.
Ga2O3
2:3 ratio of gallium atoms to oxygen atoms
2 gallium atoms and 3 oxygen atoms make one formula unit

4. formulas Electrons and charge are conserved in a formula unit.
2 gallium atoms have a total of 6 valence electrons and no charge
3 oxygen atoms have a total of 18 valence electrons and no charge
so gallium oxide (Ga2O3) has 18+6=24 valence electrons and no charge

5. conservation
Conservation of electrons and charge in gallium sulfide (Ga2S3)

6. conservation

7. oxidation numbers
Oxidation number of an ion is equal to the charge on an ion after it gains or loses electrons.
All atoms gain or lose electrons to try to attain a noble gas configuration (8 valence electrons)
Noble gases have no oxidation numbers

8. oxidation numbers
Metals – lose all valence electrons, positive (+) oxidation numbers
Metals lose electrons so as to expose full valence shell in next lower level
Alkali metals and hydrogen are +1
Alkaline earths are +2
Aluminum and friends are +3

9. oxidation states
Tin and lead are +2 or +4
Transition metals vary
Nonmetals – gain electrons, negative (-) oxidation numbers
Enough electrons are gained to complete the valence shell
Oxygen is always –2, and sulfur is –2 unless with oxygen

10. example: CO3-2 carbonate
ternary salts
Halogens are –1 unless with oxygen
Nitrogen and phosphorus are –3 unless with oxygen or halogens
Ternary salts are composed of more than two elements
Ternary salts contain polyatomic ions
Polyatomic ions contain more than one atom
example: CO3-2 carbonate

11. polyatomic ions
Polyatomic anions have a (-) charge, and polyatomic cations a (+) charge
Polyatomic ions act as a unit – the subscripts of the formula may not be changed
Names and formulas
Most names end in “-ate” or “-ite”, which means the ion contains oxygen

12. naming polyatomic ions
Examples: sulfate (SO4-2), sulfite (SO3-2)
The ending and prefix (if present) indicate the relative number of oxygen atoms in the formula.
perchlorate ClO4–
chlorate ClO3–
chlorite ClO2–
hypochlorite ClO–

13. polyatomic cations
The “-ium” ending means a positive ion (hydronium, H3O+, and ammonium, NH4+)
Multiple ions are indicated by parentheses and a subscript
Example: magnesium hydroxide is Mg(OH)2
Ammonium sulfide: (NH4)2S

14. formulas with polyatomic ions
Formulas are made the same way as the binary salts, with the criss-cross method + -2 Na
CO3 2 ( )
Ca+2 Ca
OH- 2

15. Naming ternary salts
Ternary salts are named with the metal name first, then the name of the polyatomic ion
K3PO4
potassium phosphate

16. Transition metal salts
Many transition and “other” metals have more than one oxidation number
These numbers are found on some periodic tables
Metals to know: Fe (+2, +3), Cu (+1, +2), Ag (+1), Zn (+2), Sn (+2, +4), Pb (+2, +4), Bi (+3, +5)

17. transition metal salts
Oxidation number of transition metal is indicated by a Roman numeral in parentheses
FeCl3 is iron (III) chloride
Name these: CrO
chromium (II) oxide
Cr2O3
chromium (III) oxide
CrO3
chromium (IV) oxide

18. transition metal salts
The Roman numeral is not needed if there is only one oxidation state for the metal (i.e. Zn, Ag, Sc)
The Roman numeral is also used for “other” metal salts like tin (II) fluoride (SnF2, formerly used in toothpaste)
Transition metal salts are often brightly colored

19. hydrates
Hydrates are salts that have water incorporated into the crystal structure
The water is usually associated with the cation
The number of water molecules in the crystal are specified in the formula
MgCl2. 6H2O

20. is magnesium chloride hexahydrate
hydrates
The dot means they are not chemically bonded
Names of hydrates – “hydrate” plus a prefix is added to the salt name
MgCl2. 6H2O
is magnesium chloride hexahydrate
Prefix indicates the number of water molecules

21. hydrate prefixes mono = 1 di = 2 tri = 3 tetra = 4 penta = 5 hexa = 6
hepta = 7 octa = 8
nona = 9 deca = 10

22. Formation of hydrates
Hydrates can be formed when certain salts are crystallized from water.
Example – CuSO4. 5H2O {copper (II) sulfate pentahydrate}
Hygroscopic compounds become hydrates by taking water from the air.

23. Formation of Hydrates
Example – sodium carbonate becomes sodium carbonate decahydrate
(Na2CO3. 10H2O)
Deliquescent compounds take enough water from the air to form concentrated solutions – examples: calcium chloride (CaCl2), sodium hydroxide (NaOH)