Silicon \(\ce{(Si)}\) is in Group 14 and Period 3 of the periodic table. Sodium \(\ce{(Na)}\) is in Group 1 and Period 3. (6 marks)
Compare the properties of silicon and sodium with reference to their:
-
- Metallic character
- Electrical conductivity
- Ion formation
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Metallic character:
- Sodium has much greater metallic character than silicon. Sodium is an alkali metal (Group 1) with typical metallic properties such as being shiny, malleable, and ductile.
- Silicon is a metalloid with properties intermediate between metals and non-metals.
Electrical conductivity:
- Sodium is an excellent electrical conductor, while silicon is a semiconductor. As a Group 1 metal, sodium has one valence electron that is delocalised in a metallic lattice, allowing it to move freely and conduct electricity very effectively.
- Silicon, as a metalloid, has moderate electrical conductivity that increases with temperature – its conductivity is much lower than sodium’s but higher than non-metals.
Ion formation:
- Sodium readily forms positive ions (cations) with a 1+ charge (\(\ce{Na^+}\)) by losing its single valence electron to achieve a stable electron configuration similar to neon. Silicon typically does not form simple ions due to its position as a metalloid.
- Instead, silicon forms covalent bonds by sharing its four valence electrons with other atoms. While silicon can theoretically form \(\ce{Si^4+}\) or \(\ce{Si^4-}\) ions, the energy required to remove or add four electrons is too high.
Show Worked Solution
Metallic character:
- Sodium has much greater metallic character than silicon. Sodium is an alkali metal (Group 1) with typical metallic properties such as being shiny, malleable, and ductile.
- Silicon is a metalloid with properties intermediate between metals and non-metals.
Electrical conductivity:
- Sodium is an excellent electrical conductor, while silicon is a semiconductor. As a Group 1 metal, sodium has one valence electron that is delocalised in a metallic lattice, allowing it to move freely and conduct electricity very effectively.
- Silicon, as a metalloid, has moderate electrical conductivity that increases with temperature – its conductivity is much lower than sodium’s but higher than non-metals.
Ion formation:
- Sodium readily forms positive ions (cations) with a 1+ charge (\(\ce{Na^+}\)) by losing its single valence electron to achieve a stable electron configuration similar to neon. Silicon typically does not form simple ions due to its position as a metalloid.
- Instead, silicon forms covalent bonds by sharing its four valence electrons with other atoms. While silicon can theoretically form \(\ce{Si^4+}\) or \(\ce{Si^4-}\) ions, the energy required to remove or add four electrons is too high.
