1. NAMING COMPOUNDS
The chemical formula represents the composition of each molecule.
In writing the chemical formula, in almost all cases the element farthest to the left of the periodic table is written first because it is the least electronegative.

2. NAMING COMPOUNDS
So for example the chemical formula of a compound that contains one sulfur atom and six fluorine atoms is SF6.
If the two elements are in the same Group or Family, the symbol of the element of that is lower in the group (i.e. heavier & lower electronegativity) is written first e.g. IF3.

3. Naming Covalent Compounds
In naming covalent compounds, the name of the first element in the formula is unchanged.
The suffix “-ide” is added to the second element.
Often a prefix on the name of the second element indicates the number of the element in the compound
SF6 – sulfur hexafluoride
P4O10 – tetraphosphorous decoxide
CO – carbon monoxide
CO2 – carbon dioxide

4. Naming Covalent Compounds Cont.
SF6 – sulfur hexafluoride
P4O10 – tetraphosphorous decoxide
CO – carbon monoxide
CO2 – carbon dioxide
Notice that the first element does NOT get a mono- prefix!

5. Hydrogen Cmpds Example HF - hydrogen fluoride HCl - hydrogen chloride
The binary compounds of hydrogen are special cases. They were discovered before a convention was adopted and hence their original names have stayed
Water H2O is not called dihydrogen monoxide
Hydrogen forms binary compounds with almost all non- metals except the noble gases.
Example
HF - hydrogen fluoride
HCl - hydrogen chloride
H2S - hydrogen sulfide

6. Organic Nomenclature
The molecular formulas for compounds containing C and H (called hydrocarbons) are written with C first.
Example, CH4, C2H6, etc.
Organic molecules (containing C) have a separate nomenclature

7. BINARY IONIC COMPOUNDS
Compounds formed by elements on opposite sides of the periodic table which either give up (left side = metals) or take up electrons (right side = nonmetals).
Depending on the atom, there can be an exchange of more than one electron resulting in charges greater than ±1.

8. Group IA – alkali metals – loose 1 e- to form +1 (Na+)
Group II A– alkaline earth metals –loose 2 e- to form +2 (Ca+2)
Group III A– loose three e- to form +3 (Al+3)
Group IV A– loose four e- to form +4 (Sn+4)
Group V A– accept three e- to form –3 (N-3)
Group VI A– accept two e- to form –2 (O-2)
Group VIIA – accept one e- to form –1 (Cl-1)

9. Naming BINARY IONIC compounds
Cations
For Na+, Ca2+, the name of the ion is the same except refer to the ion.
So SODIUM ION or SODIUM CATION
Anions – suffix – “ide”
So Cl- is chloride, Oxygen O2- is OXIDE & S2- is SULFIDE
NaCl - sodium chloride
CaCl2 - calcium chloride

10. Naming BINARY IONIC compounds
EXAMPLES CONT.
BaCl2
barium chloride
K2O
potassium oxide
Mg(OH)2
magnesium hydroxide
KNO3
potassium nitrate

11. Covalent, charged compounds - MOLECULAR IONS
Negative Molecular Ions
Positive Molecular Ions
End the name with “ium” or “onium”
NH4+ is ammonium, H3O + is hydronium -
NO3 - NITRATE 2-
SO4 - SULFATE
NO2 - NITRITE 3-
PO4 - PHOSPHATE

12. Transition Elements
The transition elements are chemically quite different from the metals in the “A” block, due to differences in electronic configuration
For example, Fe can loose two or three electrons to become Fe2+ and Fe3+, respectively.

13. To identify the charge of Fe in a compound the following nomenclature is used.
Fe2+ is iron(II)
Fe3+ is iron (III)
So iron(III) chloride is FeCl3
An older scheme differentiated between the lower and higher charge by ending the name of the element with “ous” to indicate the lower charge and “ic” for the higher.
ferrous chloride => FeCl2
ferric chloride => FeCl3
However, this convention does not indicate the numerical value of the charge.

14. TERTIARY IONIC COMPOUNDS
NAME THE METAL NORMALLY, WITH A ROMAN NUMERAL IF NEEDED FOR A TRANSITION METAL
NAME THE APROPRIATE POLYATOMIC ION
Au2(Cr2O7)3 Sc4(P2O7)3
Mg (SCN)2 V3(BO3)5
Gold (III) Dichromate Scandium Pyrophosphate
Magnesium Thiocyanate Vanadium (V) Borate

15. Summary of Naming Compounds

16. NAMING ACIDS Pure substance, hydrogen chloride
An acid can be defined as a substance that yields hydrogen ions (H+) when dissolved in water.
EXAMPLE: HCl
Pure substance, hydrogen chloride
Dissolved in water (H+ Cl-), hydrochloric acid
An oxoacid is an acid that contains hydrogen, oxygen, and another element.
HNO3
nitric acid
H2CO3
carbonic acid
H2SO4
sulfuric acid

18. Naming Acids Cont. Name of ion Name of Acid Sulfate = (SO4)-2
Sulfuric Acid = H2SO4
Sulfite = (SO3)-2
Sulfurous Acid = H2SO3
Hyposulfite = (SO2)-2
Doesn’t exist!

19. Representing Formulas of Covalent & Ionic Bonds

21. Formula Types: empirical molecular H2O H2O CH2O C6H12O6 O O3 N2H4 NH2
An empirical formula shows the simplest whole-number ratio of the atoms in a substance
A molecular formula shows the exact number of atoms of each element in the smallest unit of a substance
empirical
molecular
H2O
H2O
CH2O
C6H12O6 O O3
N2H4
NH2

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Revisions and additions by A. Vasto