Complete Lewis BeH2 Structure-show Molecular Geometry drawing bonds and electron dots Total # of valence electrons Central Atom # of pairs of electrons around the central atom Electron geometry Bond angles Hybridization #of lone pairs on central atom #of bonding pairs on central atom Molecular geometry Polar or nonpolar?
The Correct Answer and Explanation is :
Complete Analysis of Lewis Structure and Molecular Geometry for ( \text{BeH}_2 )
1. Lewis Structure:
- Total # of Valence Electrons:
- Beryllium (Be): 2 valence electrons
- Hydrogen (H): (1 \times 2 = 2) valence electrons
- Total: (2 + 2 = 4) valence electrons
- Drawing the Structure:
Beryllium (Be) is the central atom with two hydrogen atoms bonded to it via single bonds. Be doesn’t achieve a full octet because it is in Group 2 and can stabilize with fewer than 8 electrons.
H—Be—H2. Central Atom:
- Number of Pairs of Electrons Around Central Atom: 2 bonding pairs (no lone pairs).
3. Electron Geometry:
- Linear Geometry: The electron groups around Be are arranged linearly to minimize repulsion.
4. Bond Angles:
- (180^\circ) due to the linear arrangement.
5. Hybridization:
- sp hybridization: Beryllium forms two sp hybrid orbitals to overlap with the 1s orbitals of hydrogen.
6. Lone Pairs on Central Atom:
- 0 lone pairs.
7. Bonding Pairs on Central Atom:
- 2 bonding pairs.
8. Molecular Geometry:
- Linear.
9. Polarity:
- Nonpolar: Although the Be-H bonds are slightly polar, the molecule’s symmetry cancels out the dipole moments.
Explanation:
The structure of ( \text{BeH}_2 ) is based on the valence shell electron pair repulsion (VSEPR) theory, which predicts the molecule will adopt a linear geometry to minimize repulsion between electron pairs. Beryllium, with only 2 valence electrons, forms two sigma bonds with hydrogen atoms using sp hybrid orbitals. The absence of lone pairs on the central atom ensures there’s no distortion from the ideal geometry.
Since the linear geometry cancels any dipole moments, ( \text{BeH}_2 ) is nonpolar despite individual Be-H bonds being polar. This nonpolarity affects properties like solubility and reactivity. The molecular geometry and electronic structure highlight ( \text{BeH}_2 )’s unique characteristics due to beryllium’s electron deficiency.