VSEPR and Polarity Flashcards
What is VSEPR ?
tells the shape of a molecule
- electron geometry
- molecular shape
What is the difference between electron geometry and molecular shape ?
- electron geometry:
- molecular shape:
How to tell electron geometry and molecular shape ?
- Do Lewis structure
- determine # of centers of electron density connected to central atom (only count lone pairs of central atom)
What is electron geometry for 2 centers of electron density ?
- linear
What is electron geometry for 3 centers of electron density ?What if there’s 1 lone pair ?
- trigonal planar
- bent
What is electron geometry for 4 centers of electron density ? What’s the molecular shape if there’s 1 lone pair ? 2 lone pairs ?
- tetrahedral
- trigonal pyramidal
- bent
What is the periodic trend of electronegativity ? exception ?
- increases across, decreases down
- exception: noble gases: always the least electrongative
Practice: Electronegativity:
Arrange from least to most electronegative:
C, N, O, Ne
Ne < C < N < O
How to determine molecular polarity ?
- Draw Lewis structure
- e- geometry
- molecular shape:
- symmetrical (same
atoms, no lone pairs:
= nonpolar
- asymmetrical (diff or
same atoms + lone pairs)
= polar
Practice: Lewis Structure, geometry, shape, hybridization AND Polarity:
H3 CCHCH2
- ve-: 18
- bonds: C: 4, H:1
- search it upppp :ppp
- geometry: trigonal planar
- shape: trigonal planar
- hybridization: 4 + 0 = sp^3
- nonpolar
Practice: Lewis Structure, geometry, shape, hybridization AND Polarity:
H3 CCHCH2
- ve-: 18
- bonds: C: 4, H:1, O: 2
- search it upppp :ppp
- geometry: trigonal planar 1. ve-: 18
- bonds: C: 4, H:1, Cl: 1
- search it upppp :ppp
- geometry: tetrahedral (look at 1st carbon)
- shape: tetrahedral (look at 1st carbon)
- hybridization: 4 + 0 = sp^3
- polar
What makes an element less electronegative ?
the valence e- experience a lower effective nuclear charge
