Shapes of molecules and ions Flashcards

1
Q

How many shape names are there (main ones)?

A

There are 5 shape names

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2
Q

What are the 6 main shape names?

A
  1. Linear shape
  2. Trigonal planar
  3. Tetrahedral
  4. Trigonal bipyramid
  5. Octahedral
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3
Q

How can you predict the shape of a simple covalent molecule?

A

You can predict by the number of electrons around an atom. Each pair of electrons will repel all the other electron pairs. Therefore they will take positions as far apart as possible to minimise repulsion

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4
Q

What is the positioning of electrons far apart and repulsion between electrons referred to as? (theory)

A

The electron repulsion theory

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5
Q

What does the shape of a molecule depend on?

A

The shape of a molecule depends on the number of pairs of electrons surrounding the central atom

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6
Q

What is the shape name of a molecule with two electron pairs?
If the shape has two electron pairs how many ELECTRONS does the shape have?

A

The shape name given to a molecule with two electron pairs would be a LINEAR shape

There are four electrons within this shape type

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6
Q

What is the bond angle of a LINEAR shape?

A

180 degrees

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7
Q

What is are a few examples of linear shaped molecules

A

Carbon dioxide
Beryllium chloride
Beryllium fluoride

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8
Q

What is the shape name of a molecule with three electron pairs?
If the shape has three electron pairs how many ELECTRONS does the shape have?

A

The shape name given to a molecule with three electron pairs would be a TRIGONAL PLANAR shape

There are 6 electrons within this shape type

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9
Q

What is the bond angle of a TRIGONAL PLANAR shape?

A

120 degrees

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10
Q

What are a few examples of trigonal planar shaped molecules?

A

Boron trifluoride
Formaldehyde
Phosgene
Sulphur trioxide
Nitrate
Carbonate
Guanidinium

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11
Q

What is the bond angle of a TETRAHEDRAL shape?

A

109.5 degrees

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12
Q

What are a few examples of a tetrahedral shaped molecule?

A

Methane
Phosphate
Sulfate
Permanganate
Ammonium

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12
Q

What is the shape name of a molecule with four electron pairs?
If the shape has 4 electron pairs how many ELECTRONS does the shape have?

A

The shape name given to a molecule with four electron pairs would be a TETRAHEDRAL shape

There are 8 electrons within this shape

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13
Q

What is the shape name of a molecule with 5 electron pairs?
If the shape has 5 electron pairs how many ELECTRONS does the shape have?

A

The shape name given to a molecule with five electrons pairs would be a TRIGONAL PLANAR shape

There are 10 electrons within this shape

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14
Q

What is the bond angle of a TRIGONAL BIPYRAMIDAL shape?

A

120 degrees

14
Q

What are a few examples of a trigonal bipyramidal shaped molecule?

A

Phosphorus pentafluoride
Phosphorus pentachloride

15
Q

What is the shape name of a molecule with 6 electron pairs?
If the shape has 6 electron pairs how many ELECTRONS does the shape have?

A

The shape name given to a molecule with six electron pairs would be an OCTAHEDRAL shape

There are 12 electrons within this shape

16
Q

What is the bond angle of a OCTAHEDRAL shape?

A

90 degrees

16
Q

What are a few examples of a octahedral shaped molecule?

A

Sulfur hexafluoride
Molybdenum hexacarbonyl

17
Q

Do bonding rules change or stay the same when molecules with lone pairs of electrons are introduced?

A

Bonding rules change when molecules with lone pairs of electrons are introduced

18
Q

What affect do lone electron pairs have on the shape of molecules?

A

Lone electron pairs provide additional repulsive forces which change the bond angle

19
Q

For each lone electron pair, how much is the covalent bond reduced?

A

For each lone electron pair, the covalent bond is reduced by 2.5 degrees

20
Q

Order these in the increase of repulsion:
1. Lone pair - bonded pair
2. Lone pair - lone pair
3. Bonded pair - bonded pair

A
  1. Bonded pair - Bonded pair
  2. Bonded pair - Lone pair
  3. Lone pair - Lone pair