Chemistry 120 Handouts/Notes

Chemistry 120
Chapter Six Notes
Chapter Six:
Nomenclature—The Names of Chemical Compounds
Types of Ions
• Ions are classified according to how many atoms they contain
◦ If an ion is derived from a single atom, it is called a monatomic ion.
• Examples include Na + , O 2- , and Pb 4+ .
◦ Ions which are derived from two or more atoms are called polyatomic ions.
Polyatomic Ions
• Polyatomic ions can be described as molecules which have collectively gained or lost
electrons to become an ion.
• Being molecules, the ions themselves are held together by covalent bonds.
• From this, you would expect the atoms in a polyatomic ion to all be nonmetals.
◦ Examples: NO 3 - , ClO 4 - , NH 4
+
• However, some polyatomic ions contain metals which are able to covalently bond.
◦ Examples: Cr 2 O 7 2- , MnO 4
-
• All but one of the more common polyatomic ions are anions.
• The ammonium ion, NH 4 + , is the only common polyatomic cation.
• The common polyatomic ions must be memorized, and you must learn to recognize them in a
formula on sight.
1- anions
OH - hydroxide
-
NO 3
CN - cyanide
-
ClO 3
OCN - cyanate
-
BrO 3
SCN - thiocyanate
-
IO 3
-
MnO 4 permanganate
-
C 2 H 3 O 2
2- anions
2-
CO 3 carbonate
2-
SO 4
2-
CrO 4 chromate
2-
Cr 2 O 7
2-
C 2 O 4 oxalate
2-
SiO 3
2-
S 2 O 3 thiosulfate
2-
O 2
3- anions
3-
PO 4 phosphate
3-
BO 3
nitrate
chlorate
bromate
iodate
acetate
sulfate
dichromate
silicate
peroxide
borate
1