Drawing diagrams of electronic configurations
2 marks · EasyThe diagram below shows the electronic configuration for an atom, with shells containing 2, 5 electrons.
(a)[1 mark]
Calculate the total number of electrons in this atom.
(b)[1 mark]
State the atomic number of this atom.
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(a) 7
(b) 7
Common mistakes: adding incorrectly
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Adds the electrons in each shell correctly: 2 + 5 = 7.
A1 (b) · 1 mark · Identifies atomic number as 7 (same as total electrons). (follow-through)
Worked solution
a) Add the electrons: 2 (first shell) + 5 (second shell) = 7 electrons.
b) Atomic number = total electrons for a neutral atom, so atomic number = 7.