4.2 – Ionic and Covalent Compound Naming
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Transcript 4.2 – Ionic and Covalent Compound Naming
4.2 – Ionic and Covalent Compound Naming
Ionic Compounds:
Salt, NaCl
- are made up of positive and negative
ions arranged in a crystal structure.
(metal and non-metal)
Covalent Molecules:
- are made up of atoms sharing
electrons.
Water, H2O
(non-metal and non-metal)
Naming Ionic Compounds:
name
of an ionic compound = positive ion negative ion-ide
Ex.1: magnesium and oxygen
positive
ion negative ion-ide
Magnesium ox + ide
Magnesium oxide
Ex.2:
what is the name of Ca3N2?
Ca = calcium; N = nitrogen
Drop the end of the negative ion and add –ide
Calcium nitride
Ex.3:
What is the name of BaCl2?
Barium
chloride
Magnesium oxide
is used as a
drying agent.
Writing formulas for Ionic Compounds
Remember: positive charges must = negative charges
Ex.1: What is the formula for magnesium phosphide?
Magnesium is Mg2+ Phosphorous is P3–
Lowest common multiple of 2 and 3 is 6
3 Mg2+ ions & 2 P3– ions (6 +ve’s & 6 –ve’s)
Magnesium phosphide = Mg3P2
Ex.2: What is the formula for calcium oxide?
Calcium is Ca2+
Oxygen is O2–
1 Ca2+ ion
&
1 O2– ion
Calcium oxide = CaO
Drawing Formula Diagrams
More Examples:
Lithium
nitride
Barium sulphide
Ionic Compound with a Multivalent Metal
Multivalent: some transition metals have more than
one charge.
Roman
numerals are used after the metal name to
indicate which ion was used
Ex. 1 What is the formula manganese(III) sulphide?
This manganese is Mn3+ Sulphur is S2–
Lowest common multiple of 3 and 2 is 6
2 Mn3+ ions and 3 S2– ions
Mn2S3
You try!
What is the name for TiF4?
can be Ti4+ or Ti3+
Fluorine is F–
From the ratio in the formula you can find out it is Ti4+
1 Ti4+ ion and 4 F– ions
Titanium (IV) fluoride
Titanium
Polyatomic Ions
are made up of several atoms joined together by
covalent bonds
The
whole group has a + or – charge, not individual
atoms.
Ex.1 What is the formula of sodium sulphate?
Na+ and SO42–
Na2SO4
Ex.2: What is the name of the compound KClO?
K+ = potassium
ClO– = hypochlorite
Potassium hypochlorite
Ex.3: What is the formula for Calcium nitrate?
Ca2+
and
NO3-
Ca(NO3)2
* Note the brackets around NO3 show there are two of
the nitrate ions present
Naming Simple Covalent Compounds
Prefixes are used before the atom name to indicate
the number of atoms in the molecule.
Examples:
CO = carbon monoxide
CO2 = carbon dioxide
Write the most metallic atom (furthest
left) first, then add -ide to the end of
the second atom’s name
Examples:
What is the name of the molecule Si3P6?
Trisilicon
hexaphosphide
What is the chemical formula for the molecule
trinitrogen tetrachloride?
N3Cl4
How do you know which type it is?
To determine whether a compound is ionic or covalent:
- Examine the formula
•
•
Ionic compounds start with a metal or the ammonium ion
Covalent compounds start with a non-metal
Take the Section 4.2 Quiz