# Oxygen and sulfur are both in Group 6 of the periodic table. An atom of the most common isotope of oxygen has atomic number 8 and mass number 16. An atom of the most common isotope of sulfur has atomic number 16 and mass number 32. Explain why atoms of oxygen and sulfur have similar chemical properties, and state how the electron arrangement of a sulfur atom differs from that of an oxygen atom.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.2 Atoms · Explain · 4 marks

## Mark scheme (4 marks)

1. Both oxygen and sulfur have the same number of electrons in their outermost shell (6 outer-shell electrons)
2. It is the number of outer-shell electrons that determines chemical properties
3. A sulfur atom has more electron shells / energy levels than an oxygen atom
4. Correct electron arrangement stated for sulfur: 2, 8, 6

## Key terms

- [atomic number](https://www.gradenine.co.uk/glossary/atomic-number)
- [mass number](https://www.gradenine.co.uk/glossary/mass-number)
- [isotope](https://www.gradenine.co.uk/glossary/isotope)
- [group](https://www.gradenine.co.uk/glossary/group)

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/oxygen-and-sulfur-are-both-in-9f4de4e1) · Published by Druglandscape Ltd.