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How do we identify ionic formulas?

Ionic formulas start with metals (or NH
4
+1 )
How do we identify covalent formulas?

Covalent formulas contain only non-metals or metalloids.
How do we name ionic compounds?

Identify the compound as binary or ternary.
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
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Identify the metal as fixed charge or variable charge.
If the compound is binary, ends in –ide.
If the compound is ternary, name the anion appropriately.

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All the molecular compounds you’ll be asked to name are binary.

Molecular compounds w/ more than 2 elements are
usually organic.
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Organic compounds have their own special naming system.
Atoms in molecules don’t the number of each atom:
 mono = 1
 hexa = 6
 di = 2
 hepta = 7
 tri = 3
 octa = 8

 tetra = 4 penta = 5
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 nona = 9 deca = 10

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Prefix for first element in compound.

Omit if it’s “mono”.
Name first element.
Prefix for second element in compound.
Give stem of second element followed by suffix –ide.
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Examples:

CO = carbon monoxide


CO
2
= carbon dioxide
N
2
O = dinitrogen monoxide

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If the last letter of the prefix and the first letter of the element are both vowels, drop the last letter of the prefix.


CO = carbon monoxide, not carbon monooxide
N
2
O
5
= dinitrogen pentoxide, not dinitrogen pentaoxide
Some compounds are known only by their common names



H
2
O = water
NH
CH
4
3
= ammonia
= methane

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Write symbols in the same order they appear in the name.
Use prefixes to determine subscripts.
Metalloids are not metals.

Compounds that start with metalloids are named as molecular compounds.

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What are the names of the following molecular compounds?
 nitrogen dioxide





NO
2
SO
3
SiO
2
NO
P
2
O
5
S
4
N
4 sulfur trioxide silicon dioxide nitrogen monoxide diphosphorus pentoxide tetrasulfur tetranitride

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What are the formulas of the following molecular compounds?
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 carbon tetrachloride phosphorus trichloride selenium dibromide dinitrogen tetroxide sulfur dioxide xenon tetrafluoride diantimony trioxide
CCl
4
PCl
3
SeBr
2
N
2
O
4
SO
2
XeF
4
Sb
2
O
3