# Explain why silicon (Si) is classified as a metalloid rather than as a metal or a non-metal, referring to its position in the periodic table and its physical and chemical properties.

> IB DP Chemistry Standard Level (2023 syllabus) — S3.1 The periodic table: classification of elements · Explain · 4 marks

## Mark scheme (4 marks)

1. Silicon is located on the 'staircase' / zigzag boundary between metals and non-metals in the periodic table (period 3, group 14), a region associated with metalloids.
2. Silicon has a physical property characteristic of metals: it has a lustrous / shiny appearance, OR it has a high melting point / is solid at room temperature.
3. Silicon has a physical property characteristic of non-metals: it is brittle / not malleable or ductile, OR it is a semiconductor rather than a good conductor of electricity.
4. Because silicon exhibits properties intermediate between metals and non-metals (both metallic and non-metallic character), it does not fit neatly into either category and is therefore classified as a metalloid.

## Key terms

- [metalloid](https://www.gradenine.co.uk/glossary/metalloid)
- [periodic table](https://www.gradenine.co.uk/glossary/periodic-table)

## Related

- [Revision notes for IB DP Chemistry Standard Level (2023 syllabus)](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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-silicon-si-is-classified-286f201f) · Published by Druglandscape Ltd.