What is the lewis structure for silicon tetrachloride, SiCl4?
The correct answer and explanation is:
Lewis Structure for Silicon Tetrachloride (SiCl₄):
Correct Lewis Structure:
Cl
|
Cl – Si – Cl
|
Cl
Each chlorine (Cl) atom has three lone pairs of electrons, and the silicon (Si) atom forms four single bonds with the chlorine atoms.
300-Word Explanation:
Silicon tetrachloride (SiCl₄) is a covalent compound made up of one silicon atom and four chlorine atoms. To draw its Lewis structure, we follow a step-by-step process:
1. Count the Total Valence Electrons
- Silicon (Si) is in Group 14: 4 valence electrons
- Chlorine (Cl) is in Group 17: 7 valence electrons × 4 = 28 electrons
- Total valence electrons = 4 (Si) + 28 (Cl) = 32 electrons
2. Choose the Central Atom
Silicon is less electronegative than chlorine, so it goes at the center. Chlorine atoms surround it.
3. Form Single Bonds
Connect each chlorine atom to silicon with a single bond. Each single bond uses 2 electrons × 4 bonds = 8 electrons used, 24 remaining.
4. Complete the Octets of Outer Atoms
Each chlorine atom needs 6 more electrons (3 lone pairs) to complete its octet:
- 6 electrons × 4 Cl = 24 electrons used
Now all 32 electrons are placed, and each atom has a full octet.
5. Check the Octet Rule
- Silicon has 4 bonds (8 electrons), fulfilling the octet rule.
- Each chlorine has 1 bond + 3 lone pairs = 8 electrons.
6. Shape and Polarity
The molecular geometry is tetrahedral due to four regions of electron density around silicon. Since the four Cl atoms are symmetrically arranged, SiCl₄ is non-polar, despite having polar bonds.
This Lewis structure accurately represents bonding and lone pairs, making SiCl₄ a good example of tetrahedral covalent geometry.