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A molecule is the smallest particle that has any of the
properties of a compound. The formula for a molecule must be neutral. When
writing the formula for an ionic compound, the charges on the ions must
balance, the number of postive charges must equal the number of negative
charges.
Examples:
| CaCl2 |
Balanced formula has 2 positive charges (1 calcium ion with +2
charge) and 2 negative charges (2 chloride ions with a -1
charge) |
| Al2(SO4)3 |
Balanced formula has 6 positive charges (2 aluminum ions with
a +3 charge) and 6 negative charges (3 sulfate ions with -2
charge) |
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