Determine PH2- electron pair geometry: What is electron pair geometry for TeCl42-? What is electron pair geometry of CH3+?
The Correct Answer and Explanation is:
To determine the electron pair geometry for both TeCl4²⁻ and CH3⁺, we need to analyze their molecular structures using the VSEPR theory (Valence Shell Electron Pair Repulsion), which helps predict the geometry of molecules based on the repulsion between electron pairs.
1. TeCl4²⁻ (Tellurium Tetrachloride Ion)
- Central Atom: Tellurium (Te)
- Charge: The charge is 2- (TeCl4²⁻), meaning the molecule has 2 extra electrons compared to a neutral TeCl4.
- Electron Configuration of Te: Tellurium has an atomic number of 52 and an electron configuration of [Kr]5s²4d¹⁰5p⁴.
- Electron Pairs: In TeCl4²⁻, Tellurium forms four bonds with chlorine atoms, and the extra 2 electrons contribute to lone pairs on Te. This gives 4 bonding pairs and 2 lone pairs on the Te atom.
- Electron Pair Geometry: According to VSEPR theory, 6 electron pairs around the central atom (4 bonding pairs and 2 lone pairs) will arrange themselves in an octahedral geometry. The lone pairs will occupy opposite positions to minimize repulsion, but the electron pair geometry remains octahedral.
2. CH3⁺ (Methylium Ion)
- Central Atom: Carbon (C)
- Charge: The positive charge on the molecule (CH3⁺) indicates that one electron has been removed from the carbon atom.
- Electron Configuration of C: Carbon has an atomic number of 6, and its neutral electron configuration is 1s²2s²2p². In CH3⁺, after losing an electron, carbon has 3 bonding pairs (one for each hydrogen).
- Electron Pairs: In CH3⁺, there are 3 bonding pairs and 0 lone pairs on carbon.
- Electron Pair Geometry: The 3 bonding pairs will arrange themselves in a trigonal planar geometry to minimize electron repulsion, according to VSEPR theory.
Summary of Electron Pair Geometries:
- TeCl4²⁻ has an octahedral electron pair geometry.
- CH3⁺ has a trigonal planar electron pair geometry.
These geometries are based on minimizing the repulsion between bonding and lone electron pairs around the central atom.
