Molecular orbitals homonuclear diatomic molecules Flashcards

1
Q

What are homonuclear diatomic molecules?

A

Molecules that consist of two atoms from the same element

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2
Q

What are the 5 steps involved?

A
  1. Construct molecular orbitals
  2. For each combination of two atomic orbitals, obtain two molecular orbitals
  3. Allocate valence electrons to the molecular orbitals
  4. Calculate bond order
  5. Look for unpaired electrons
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3
Q

What do two 2s orbitals combine to form?

A

they combine in phase and out of phase to give σ and σ* MO

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4
Q

What do two 2Pz orbitals combine to form?

A

They combine in phase and out of phase to give σ and σ* MO

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5
Q

What do two 2Px and 2Py orbitals combine to form?

A

They combine in phase and out of phase to give two π and two π* MO

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6
Q

What effect does a large overlap integral have on bonding MO’s?

A

The will be more stable and have less energy

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7
Q

What effect does a large overlap integral have on antibonding MO’s?

A

They will be less stable and have more energy

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8
Q

Which is higher in energy, 2p or 2s?

A

2p

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9
Q

What other symbols can be given to the symmetry of the atoms towards the mathematical operation of inversion?

A

g

u

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10
Q

What does g mean? (MO symmetry)

A

Gerade

Even

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11
Q

What does u mean? (MO symmetry)

A

Ungerade

Uneven

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12
Q

When allocating valence electrons, which orbitals are filled first and why?

A

Bonding

Lower in energy

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13
Q

Which electrons do you ignore when allocating electrons to molecular energy diagrams?

A

Core electrons eg. 1s2

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14
Q

How do you calculate bond order?

A

1/2 (Number of bonding electrons - number of antibondung electrons)

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15
Q

What does a higher bond order mean for the type of bond?

A

Shorter and stronger

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16
Q

What does paramagnetic mean?

A

A substance that has unpaired electrons

17
Q

What does diamagnetic mean?

A

A substance that has no unpaired electrons

18
Q

When can s and p mix?

A

When they have the same geometry

19
Q

How do you name the orbitals when there is sp mixing?

A

eg. σ1, σ2 etc

20
Q

What are the consequences of adding more antibonding electrons?

A

bond strength decreases

bond length increases