Draw the Lewis Structure for SiH4 and Determine Its Molecular Shape, Electron Pair Geometry, and Hybridization

To draw the Lewis structure for SiH₄ (silane), follow these steps:

1. Count the total number of valence electrons: Silicon (Si) has 4 valence electrons, and each hydrogen (H) has 1 valence electron. Since there are 4 hydrogen atoms, the total number of valence electrons is 4 (from Si) + 4 × 1 (from H) = 8 electrons.
2. Place the least electronegative atom in the center: Silicon is less electronegative than hydrogen, so it will be the central atom.
3. Connect the atoms with single bonds: Draw single bonds between the silicon atom and each hydrogen atom. This uses up 4 × 2 = 8 electrons (2 electrons per bond).
4. Check the octet rule: Silicon has 4 electrons around it (from the 4 single bonds), satisfying the octet rule. Each hydrogen atom has 2 electrons (from the single bond), satisfying the duet rule.

a. Molecular Shape: The molecular shape of SiH₄ is tetrahedral. This is because the four hydrogen atoms are arranged symmetrically around the central silicon atom, with bond angles of approximately 109.5°.

b. Electron Pair Geometry at the Central Atom: The electron pair geometry around the central silicon atom is also tetrahedral. This is because there are four regions of electron density (the four Si-H bonds) around the silicon atom.

c. Hybridization of the Central Atom: The hybridization of the central silicon atom is sp³. This is because the silicon atom forms four sigma bonds with the hydrogen atoms, requiring the mixing of one 3s orbital and three 3p orbitals to form four equivalent sp³ hybrid orbitals.