Counting the number of electrons in an atom
3 marks · EasyState what is meant by the atomic number of an atom.
Draw a table to show the number of electrons in each of the following neutral atoms:
| Element | Atomic number |
|---|---|
| Beryllium | 4 |
| Fluorine | 9 |
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) The number of protons in the nucleus of an atom · must show references to protons, reference to atomic nucleus or atom
(b) — · must show Beryllium: 4 electrons, Fluorine: 9 electrons
Must show: correct statement in (a), numbers of electrons for beryllium and fluorine in (b)
Common mistakes: Confusing atomic number with mass number; Not matching number of electrons with atomic number
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Defines atomic number as the number of protons in the nucleus.
B2 (b) · 1 mark · Correctly gives number of electrons in beryllium (4).
B3 (b) · 1 mark · Correctly gives number of electrons in fluorine (9).
Worked solution
a) Atomic number is the number of protons in the nucleus of an atom.
b)
| Element | Atomic number | Number of electrons |
|---|---|---|
| Beryllium | 4 | 4 |
| Fluorine | 9 | 9 |