6 Shapes of Molecules and Intermolecular Forces Flashcards

1
Q

Does a lone pair or bonded pair repel more strongly? (1 mark)

A

Lone pair

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2
Q

Why does a lone pair repel more strongly than a bonded pair? 2 marks)

A

A lone pair is slightly closer to the central atom, and occupies more space.

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3
Q

What is the bond angle decreased by for each lone pair? (1 mark)

A

2.5 degrees

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4
Q

What is the bond angle and shape of methane? (2 marks)

A

Tetrahedral
109.5

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5
Q

What is the bond angle of a tetrahedral molecule? (1 mark)

A

109.5

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6
Q

What is the shape of a molecule with bond angle 109.5?

A

Tetrahedral

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7
Q

What is the shape and bond angle of a molecule with 4 bonded pairs and no lone pairs? (2 marks)

A

Tetrahedral 109.5

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8
Q

What is the shape and bond angle of ammonia? (2 marks)

A

Pyramidal
107

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9
Q

What is the bond angle of a molecule with a pyramidal shape? (1 mark)

A

107

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10
Q

What is the shape of a molecule with bond angle 107? (1 mark)

A

Pyramidal

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11
Q

What is the shape and bond angle of a molecule with 2 bonded pairs and 2 lone pairs? (2 marks)

A

Non- linear
104.5

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12
Q

What is the shape of a molecule with bond angle 104.5? (1 mark)

A

Non-linear

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13
Q

What is the shape and bond angle of a molecule with three bonded paired and one lone pair? (2 marks)

A

Pyramidal
107

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14
Q

What is the bond angle of a molecule with a non-linear shape? (1 mark)

A

104.5

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15
Q

What is the shape and bond angle of water? (2 marks)

A

Non-linear
104.5

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16
Q

What is the shape of a molecule with 2 electron regions? (2 marks)

A

Linear

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17
Q

What is the bond angle of a linear molecule? (1 mark)

A

180

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18
Q

What is the bond angle and shape of carbon dioxide? (2 marks)

A

Linear
180

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19
Q

What is the shape of a molecule with bond angle 180? (1 mark)

A

Linear

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20
Q

What is the shape and bond angle of a molecule with 3 electron pairs/regions?

A

Trigonal planar
120

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21
Q

What is the shape of a molecule with bond angle 120? (1 mark)

A

Trigonal planar

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22
Q

What is the shape and bond angle of BF3? (2 marks)

A

Trigonal planar
120

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23
Q

What is the bond angle of a molecule with a trigonal planar shape? (1 mark)

A

120

24
Q

What is the bond angle and shape of sulphur hexafluoride? (2 marks)

A

Octahedral
90

25
Q

What is the bond angle of a molecule with an octahedral shape? (1 mark)

A

90

26
Q

What is the bond angle and shape of a molecule with 6 electron pairs/regions? (2 marks)

A

90
Octahedral

27
Q

What is the shape of a molecule with bond angle 90? (1 mark)

A

Octahedral

28
Q

What is electronegativity? (1 mark)

A

The attraction of a bonded atom for the pair of electrons in a covalent bond.

29
Q

How is electronegativity measured? (1 mark)

A

The Pauling scale

30
Q

Describe electronegative on the periodic table. (2 marks)

A

The top right of the periodic table contains the most electronegative elements. With Florine being in the corner (ignore group 0).

31
Q

Is an ionic or covalent bond more electronegative? (1 mark)

A

Ionic

32
Q

What is the electronegativity difference of a covalent bond? (1 mark)

A

0

33
Q

What is the electronegativity difference of a polar covalent bond? (1 mark)

A

0 to 1.8

34
Q

What is the electronegativity difference of an ionic bond? (1 mark)

A

Greater than 1.8

35
Q

What does a bond being non-polar mean? (1 mark)

A

The bonded electron pair is shared equally between the bonded atoms.

36
Q

What does it mean when a bond is described as polar? (1 mark)

A

The bonded electron pair is shared unequally between the bonded atoms.

37
Q

Why is carbon dioxide non-polar even though it contains two C=O bonds with permanent dipoles? (1 mark)

A

The two dipoles act I’m opposite directions and exactly oppose each other (due to a linear shape).

38
Q

What are the three main catagories of intermolecular forces? (3 marks)

A

Induced dipole-dipole interactions
Permanent dipole-dipole interactions
Hydrogen bonding

39
Q

Which intermolecular force is the strongest? (1 mark)

A

Hydrogen bond

40
Q

Which intermolecular bond is the weakest? (1 mark)

A

Induced dipole-dipole interactions

41
Q

Where are induced dipole-dipole interactions? (2 marks)

A

Exist between all molecules.
They act between induced dipoles in different molecules.

42
Q

Describe the origin of induced dipole-dipole interactions. (3 marks)

A

Movement of electrons produces a changing dipole in a molecule.
At any instant, an instantaneous dipole will exist (position is alway shifting).
This instantaneous dipole induces a dipole on a neighbouring molecule.
Etc.

43
Q

Describe the strength of the induced dipole-dipole interactions in a molecule with more electrons. (3 marks)

A

Larger instantaneous and induced dipoles
Greater the induced dipole-dipole interactions
The stronger the attractive forces between molecules.

44
Q

What are permanent dipole-dipole interactions? (2 marks)

A

They act between the permanent dipoles in different polar molecules.

45
Q

Describe the bonding and intermolecular forces in a simple molecular lattice. (2 marks)

A

Strong covalent bonds
Weak intermolecular forces.

46
Q

What happened when a simple non-polar molecular substance is added to a non-polar solvent? (3 marks)

A

Intermolecular forces form between the molecules and the solvent.
The interactions weaken the intermolecular forces in the simple molecular lattice.
The intermolecular forces break.
The compound dissolves.

47
Q

Why are non-polar simple molecular substances insoluble in polar solvents? (2 marks)

A

The intermolecular bonding within the polar solvent is too strong to be broken, so there is little interaction between the molecules keep s in the lattice and the solevent molecules.

48
Q

What is the solubility of a polar simple molecular substance dependent on? (1 mark)

A

The strength of the dipole.

49
Q

Describe the electrical conductivity of simple molecular structures. (2 marks)

A

There are no mobile charge carriers, so they do not conduct electricity.

50
Q

What three elements can form a hydrogen bond with H? (3 marks)

A

Oxygen
Nitrogen
Fluorine

51
Q

Why is ice less dense than water? (2 marks)

A

Hydrogen bonds hold water molecules apart in an open lattice structure in ice.

52
Q

Why does water have a relatively high melting and boiling point? (2 marks)

A

Hydrogen bonds are really strong, require more energy to be broken.

53
Q

What is the bond angle of a molecule with a square planar shape? (1 mark)

A

90 degrees

54
Q

How many lone/bonded pairs of electrons does a molecule with a square planar shape have? (2 marks)

A

4 bonded
2 lone

55
Q

Which elements form a square planar shape? (3 marks)

A

Au
Pt
Pd