Molecular Shape and VSEPR Flashcards
What is VSEPR theory?
- Effective in predicting the shapes of molecules.
- Focuses on pairs of electrons in the valence shell of the central atom.
- Based on the idea that valence shell electron pairs repel each other.
- Electron pairs assume orientations to minimize repulsions.
- The force of repulsion between two electron pairs is much greater at an angle of 90degrees than 120 or 180.
Order the amount of repulsion of Lone pairs and bonding pairs from strongest to weakest.
LP-LP, LP-BP, BP-BP
What does VSEPR stand for?
Valence shell electron pair repulsion theory.
What is VSEPR notation?
AXnEm (where A is central atom, X is atoms bonded to central atom, E is lone electron pairs)
What are the 4 steps for predicting Molecular Shape?
- Draw the Lewis structure of the molecule.
- Determine the total number of electron pairs around the central atom.
- Determine the geometric arrangement based on the number of electron pairs.
- Determine the molecular shape from the position occupied by the bond pairs and lone pairs.
What is the electronic geometry of AX2 molecules?
Linear
What is the electronic geometry of AX3 molecules?
Trigonal Planar
What is the electronic geometry of AX4 molecules?
Tetrahedral
What is the electronic geometry of AX5 molecules?
Trigonal bipyramidal
What is the electronic geometry of AX6 molecules?
Octahedral
What is the molecular shape/geometry distribution of AX2E1?
Bent
What are the bond angles of AX2 linear molecule?
180 degrees
What is the molecular shape/geometry distribution of AX3E1?
Trigonal pyramidal
What is the molecular shape/geometry distribution of AX2E2?
Bent
What is the molecular shape/geometry distribution of AX4E1?
see-saw
What is the molecular shape/geometry distribution of AX3E2?
T-shaped
What is the molecular shape/geometry distribution of AX2E3?
Linear
What is the molecular shape/geometry distribution of AX5E1?
Square pyramidal
What is the molecular shape/geometry distribution of AX4E2?
Square planar
What are the possible molecular shapes of 2?
linear
What are the possible molecular shapes of 3?
Trigonal planar, bent
What are the possible molecular shapes of 4?
Tetrahedral, Trigonal pyramidal, bent
What are the possible molecular shapes of 5?
Trigonal Bipyramidal, see-saw, T-shaped, linear
What are the possible molecular shapes of 6?
Octahedral, square pyramidal, square planar
What are the bond angles of trigonal planar molecules?
AX3 is 120
AX2E1 is less than 120
What are the bond angles of tetrahedral molecules?
AX4 is 109.5
AX3E1 is 107
AX2E2 is 104.5
What are the bond angles of trigonal bipyrimidal molecules?
They are all 120/90 (120 is equatorial, 90 is axial) except AX2E3 (180)
What are the bond angles of octahedral molecules?
90
What shape is CO2?
Linear (AX2)
What shape is BF3?
Trigonal planar
What shape is CH4?
Tetrahedral AX4
WHat shape is NH3?
Trigonal pyramidal AX3E1
What shape is H2O?
Bent AX2E2
What shape is PF5?
Trigonal bipyramidal AX5
What shape is SF4?
See-saw AX4E1
What shape is ClF3?
T-shaped AX3E2
What shape is SF6?
Octahedral AX6
What shape is IF5?
Square pyramidal AX5E1
What shape is XeF4?
Square planar AX4E2