It is the mass of the atoms of an element (Ar) compared with carbon which is 12, and is an average of all the isotopes.
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What are isotopes?
Isotopes are atoms of the same element but with different numbers of neutrons. For example 35Cl and 37Cl. Both isotopes have 17 protons and 17 electrons. However, 35Cl has 18 neutrons and 37Cl has 20 neutrons.
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The percentage abundance for 35Cl is 75% and The percentage abundance for 37 Cl 25%. Calculate the Relative Atomic Mass of Cl.
Ar = ((35 x 75)+(37 x 25))/100 = 35.5
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What is the relative formula mass?
It is the mass of a compound (Mr) calculated using the relative mass (Ar) of each of the element present in its formula.
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Using a periodic table, calculate the relative formula mass Mr of KOH.
Mr = 39+16+1 = 56
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Using a periodic table, calculate the relative formula mass Mr of Na2CO3.
Mr = (23x2)+12+(16x3) = 106
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Other cards in this set
Card 2
Front
What are isotopes?
Back
Isotopes are atoms of the same element but with different numbers of neutrons. For example 35Cl and 37Cl. Both isotopes have 17 protons and 17 electrons. However, 35Cl has 18 neutrons and 37Cl has 20 neutrons.
Card 3
Front
The percentage abundance for 35Cl is 75% and The percentage abundance for 37 Cl 25%. Calculate the Relative Atomic Mass of Cl.
Back
Card 4
Front
What is the relative formula mass?
Back
Card 5
Front
Using a periodic table, calculate the relative formula mass Mr of KOH.
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