Atomic number and mass number
2 marks · EasyExplain why the atomic number is important in identifying an element.
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Must show: atomic number unique to element, each element has different number of protons
Also accept: Atomic number is unique for each element and tells us the number of protons in its nucleus.
Common mistakes: Confusing atomic number with mass number; Saying atomic number shows the mass
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Marking points
B1 · 1 mark · States that atomic number is unique to each element
B2 · 1 mark · Explains that it gives the number of protons in the nucleus, which defines the element
Worked solution
The atomic number is important because it is unique to each element. It tells us how many protons are in the nucleus, so each element has a different atomic number and cannot be confused with another.