Valence bond theory

Question 1

advantage of vb theory over lewis structures?

Answer 1

describes electron distribution in terms of orbitals, not just a dot to represent the one location of an electron

Question 2

in terms of localisation

Answer 2

describes electrons as being localised in a bond or as a lone pair

Question 3

advantages of valence bond

Answer 3

predicts molecular bonding and shape

Question 4

disadvantages of valence bond theory

Answer 4

doesnt explain delocalisatioin or spectral properties well

Question 5

what are hybrid orbitals

Answer 5

atomic orbitals combine to form hybrid orbitals

Question 6

describe sp hybrid orbital

Answer 6

2s orbital and 2px orbital overlap to form 2x sp orbitals. energy the average.

• since 2 orbitals are formed, they form linear geo to minimise repulsions
• 2py and 2pz unhybridised

Question 7

describe sp2 orbital

Answer 7

2s orbital and 2px and 2py orbitals combine to form 3 sp2 orbitals. 2/3 p character, 1/3 s character (and hence energy)
-since 3 orbitals are formed, they form trig planar

Question 8

describe sp3 orbital

Answer 8

2s and 2px/y/z orbital combine to form 4 sp3 orbitals. 3/4 p character/energy.
-since four orbitals are made, they form tetrahedral geo to minimise repulsions.

Question 9

describe sigma bonds

Answer 9

when unpaired electrons in hybrid orbitals overlap

Question 10

describe pi bonds

Answer 10

when unpaired electrons in atomic (nonhybridised) orbitals overlap