Nomenclature
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Transcript of Nomenclature
Nomenclature
Ionic Compounds
• Held together by ionic bonds.
• What are ionic bonds?– Between metals and
non-metals– Transfer of electrons
between atoms.– Attraction between
oppositely charged ions.
Ionic Compounds
• Some examples are:– NaCl
– MgCl2– KBr
– Li2O
• These are all bonds between cations (positive ions) and anions (negative ions).
Naming Ionic Compounds
• Binary Ionic Compounds– The metal will be your cation. Its name comes
first.– The non-metal will be your anion. Its name
comes second, but undergoes a slight change.• Change the ending to –ide. • Example: Chlorine Chloride, Nitrogen Nitride
•Li2O Lithium + Oxygen
Metal Non-Metal
ide
Practice
• Name the following ionic compounds:
– MgCl
– Rb2S
– BeF2
– Cs3N
– KI
– In ionic compounds, the subscripts do NOT affect the name of the compound.
Magnesium Chloride
Rubidium Sulfide
Beryllium Fluoride
Cesium NitridePotassium Iodide
Naming Ionic Compounds
• Polyatomic Ions NAC book page 235– Ions made of multiple atoms.– Name using an ion chart, but otherwise
name the same as binary compounds.– Examples:
– MgCO3 = Magnesium Carbonate
– (NH4)2SO4 = Ammonium Sulfate
Writing Formulas from Names• The key to writing correct ionic
formulas is to balance your positive and negative charges. We want a neutral molecule.
• The charge of the cation becomes the subscript of the anion .
• The charge of the anion becomes the subscript of the cation.
Writing Formulas From Names
• Sodium Chloride• Sodium = Na+, Chlorine = Cl-
Na1Cl1
NaCl
Writing Formulas from Names
• Magnesium Fluoride• Magnesium = Mg2+, Fluorine = F-
Mg1F2
MgF2
**Do not include the charge in your formula.
Why does this work?• Magnesium Fluoride
2+
-1
-1
2 + -2 = 0
Magnesium Fluorine
Ionic Naming using Transition Metals (and Tin and Lead)
• The charges of transition metals can vary.
• A transition metal can have different charges depending on the situation.
• You can use the formula to determine its charge in a specific molecule.
Example #1• CuI2• We know Iodine has a charge of -1, but we have to
determine the charge of copper.
+?
-1
-1
Copper Iodine
____ + -2 = 0
So… the charge of Copper in this molecule must be +2.
The name is written:
Copper (II) Iodide
Example #2• Mn2Cl4
+?
-1
-1
-1
-1
+?
Manganese Chlorine
2 x ? + -4 = 0
We are trying to find the charge of one Manganese atom.
The charge of one Manganese atom is +2, so the formula for Mn2Cl4 is:
Manganese (II) Chloride
Practice
• NiS2
• AgF
• Sn3N4
• Lead (III) Phosphide
• Titanium (IV) Chloride
• Chromium (II) Iodide
Writing Formulas from Names• You can write the formulas for ionic compounds
using transition metals the same as ionic compounds using alkali or alkaline earth metals.
Mercury (I) Sulfide
Mercury = Hg+, Sulfur = S2-
Hg2S
Molecular Compounds• Held together by Covalent bonds.
– Between non-metals.– Sharing of electrons
• Examples:– H2O
– C2H4
– SO
Naming Molecular Compounds
• Begin by writing the name as you would a binary ionic compound.
• Add prefixes to each name which tell you how many of that atom are in the molecule.– If there is only one atom
of the first element in the molecule you can leave out the “mono” prefix on the first element only.
Prefix Definitions
Mono = 1
Di = 2
Tri = 3
Tetra = 4
Penta = 5
Hexa = 6
Hepta = 7
Octa = 8
Nona = 9
Deca = 10
Practice
• P2S3
• H2O
• CO
• N2O4
Metal + Non-metal or presence of polyatomic
ion
2 non-metals (Carbon, Silicon, elements in
groups 15-17, or Hydrogen)
Includes Transition metal,
Lead or Tin
Name using prefixes. Charges are not
relevant.
Includes Alkali or
Alkaline Earth Metal
Must include charge of
transition metal in parentheses.
Name using binary ionic
rules. No charge in
parentheses needed.