Relative atomic mass
2 marks · EasyExplain why isotopes of calcium all react in the same way, even though they have different numbers of neutrons.
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Because isotopes have the same number of protons and electrons, so their electronic structure (which determines chemical properties) is the same.
Also accept: Because their electron arrangement is the same; Their chemical properties are determined by electrons, which are unchanged in isotopes
Common mistakes: Because they are the same element (incomplete explanation)
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Marking points
B1 · 1 mark · States that chemical properties depend on electron arrangement/number of electrons, not neutrons.
B2 · 1 mark · States that isotopes have the same number of electrons (or protons), so react the same way.
Worked solution
Isotopes of calcium have the same number of protons and electrons. Chemical reactions depend on the arrangement of electrons, so all calcium isotopes react alike even though they have different numbers of neutrons.