# Isotopes and Relative Atomic Mass

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• Created by: joshd
• Created on: 29-03-14 16:27
What ARE isotopes? (Isotopes cannot be described singularly)
Isotopes ARE different atomic forms of the same element, which have the SAME number of PROTONS, but DIFFERENT numbers of NEUTRONS.
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What must isotopes have and what must they have different?
Isotopes must have the same number of protons but different mass numbers.
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What would it mean if they had different a different number of protons?
They would be different elements.
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What's a popular pair of isotopes?
carbon-12 and carbon-14 (DIAGRAM ON PAGE 44)
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What does relative atomic mass? (Ar) What does it have to allow?
Relative atomic mass (Ar) uses the average mass of the isotopes of an element. It has to allow for the relative mass of each isotope and its relative abundance.
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What is relative abundance? What can it be represented in?
Relative abundance means how much there is of each isotope compared to the total amount of the element in the world. This can be a ratio, fraction or a percentage.
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What do you do first to find relative atomic mass? (1)
First, multiply the mass of each isotope by its relative abundance.
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What do you do second to find relative atomic mass? (2)
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What do you do third to find relative atomic mass? (3)
Divide by the sum of the relative abundances.
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What do relative atomic masses usually not come out as?
Relative atomic masses don't usually come out as whole numbers or easy decimals, but they're often rounded to the nearest 0.5 in periodic tables.
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## Other cards in this set

### Card 2

#### Front

What must isotopes have and what must they have different?

#### Back

Isotopes must have the same number of protons but different mass numbers.

### Card 3

#### Front

What would it mean if they had different a different number of protons?

### Card 4

#### Front

What's a popular pair of isotopes?

### Card 5

#### Front

What does relative atomic mass? (Ar) What does it have to allow?