# How much?

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What is an isotope?
An isotope is an atom of the same element with a different number of neutrons (mass number)
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Calculate the average mass of chlorine given that 75% is chlorine 35 and 25% is chlorine 37.
75% of 35 = 26. 25% of 37 = 9.25 26.25 + 9.25 = 35.5
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Bromine contains 50.5% bromine-79 and 49.5% bromine- 81.
50.5 / 100 = 0.505 x 79 = 39.395 49.5 / 100 = 0.495 x 81 = 40.095 39.895 + 40.095 = 79.99
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How do you calculate the mass of the compound?
You add all of the mass numbers together
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Calculate the mass of calcium carbonate.
40+12+16+16+16= 100g
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How do you calculate percentage composition?
(number of atoms in element) x (atomic mass of element) x 100 / Formula mass of the compound
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## Other cards in this set

### Card 2

#### Front

Calculate the average mass of chlorine given that 75% is chlorine 35 and 25% is chlorine 37.

#### Back

75% of 35 = 26. 25% of 37 = 9.25 26.25 + 9.25 = 35.5

### Card 3

#### Front

Bromine contains 50.5% bromine-79 and 49.5% bromine- 81.

### Card 4

#### Front

How do you calculate the mass of the compound?

### Card 5

#### Front

Calculate the mass of calcium carbonate.