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Chemistry A-Level > Module 2 - Bonding and Structure > Flashcards

Module 2 - Bonding and Structure Flashcards

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1
Q

What are the 3 main types of
chemical bonds?

A

● Ionic
● Covalent
● Metallic

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2
Q

Define ionic bonding

A

The electrostatic attraction between
positive and negative ions

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3
Q

Give an example of a ionically
bonded substance

A

NaCl (Sodium Chloride - salt)

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4
Q

Define covalent bonding

A

Electrostatic attraction between a shared
pair of electrons and the nuclei

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5
Q

Define metallic bonding

A

Electrostatic attraction between the
positive metal ions and the sea of
delocalised electrons

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6
Q

Electrons in which shell are
represented in a dot and cross
diagram?

A

The outer shell

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7
Q

Why does giant ionic lattices
conduct electricity when liquid
but not when solid?

A

In solid state the ions are in fixed
positions and thus cannot move. When
they are in liquid state the ions are
mobile and thus can freely carry the
charge

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8
Q

Giant ionic lattices have high
or low melting and boiling
point? Explain your answer

A

They have high melting and boiling point
because a large amount of energy is
required to overcome the electrostatic
bonds

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9
Q

In what type of solvents do
ionic lattices dissolve?

A

Polar solvents
E.g water

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10
Q

Why are ionic compounds
soluble in water?

A

Water has a polar bond. Hydrogen atoms
have a delta + charge and oxygen atoms
have a delta - charge. These charges are
able to attract charged ions

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11
Q

What is it called when atoms
are bonded by a single pair of
shared electrons?

A

Single bond

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12
Q

How many covalent bonds
does carbon form?

A

4

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13
Q

How many covalent bonds
does oxygen form?

A

2

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14
Q

What is a lone pair?

A

Electrons in the outer shell that are not
involved in the bonding

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15
Q

What is formed when atoms
share two pairs of electrons?

A

Double bond

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16
Q

What is formed when atoms
share three pairs of electrons?

A

Triple bond

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17
Q

What is average bond
enthalpy?

A

Measure of average energy needed to
break the bond

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18
Q

What is a dative covalent
bond?

A

A bond where both of the shared
electrons are supplied by one atom

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19
Q

How are oxonium ions
formed?

A

Formed when acid is added to water,
H3O+

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20
Q

What does expansion of the
octet mean?

A

When a bonded atom has more than 8
electrons in the outer shell

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21
Q

What are the types of covalent
structure?

A

● Simple molecular lattice
● Giant covalent lattice

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22
Q

Describe the bonding in simple
molecular structures

A

Atoms within the same molecule are held
by strong covalent bonds and different
molecules are held by weak
intermolecular forces

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23
Q

Why do simple molecular
structures have low melting
and boiling point?

A

Small amount of energy is enough to
overcome the intermolecular forces

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24
Q

Can simple molecular
structures conduct electricity?

A

No, they are non conductors.

25
Q

Why do simple molecular
structures not conduct
electricity?

A

The have no free charged particles to
move around

26
Q

Simple molecular structures
dissolve in what type of
solvent?

A

Non polar solvents

27
Q

Give examples of giant
covalent structures

A

● Diamond
● Graphite
● Silicon dioxide, SiO2

28
Q

List some properties of giant
covalent structures? (3)

A

● High melting and boiling point
● Non conductors of electricity, except graphite
● Insoluble in polar and non polar solvents

29
Q

How does graphite conduct
electricity?

A

Delocalised electrons present between
the layers are able to move freely
carrying the charge

30
Q

Why do giant covalent
structures have high melting
and boiling point?

A

Strong covalent bonds within the
molecules need to be broken which
requires a lot of energy

31
Q

Draw and describe the
structure of a diamond

A

3D tetrahedral structure of C atoms, with each C atom
bonded to four others

32
Q

What does the shape of a
molecule depend on?

A

Number of electron pairs in the outer shell
Number of these electrons which are bonded and
lone pairs

33
Q

What is the shape, diagram
and bond angle in a shape
with 2 bonded pairs and 0 lone
pairs?

A

Linear
180°

34
Q

What is the shape, diagram
and bond angle in a shape
with 3 bonding pairs and 0
lone pairs?

A

Trigonal planar
120°

35
Q

What is the shape, diagram and
bond angle in a shape with 4
bonded pairs and 0 lone pairs?

A

Tetrahedral
109.5°

36
Q

What is the shape,diagram
and bond angle in a shape
with 6 bonded pairs and 0 lone
pairs?

A

Octahedral
90°

37
Q

What is the shape, diagram
and bond angle in a shape
with 3 bonded pairs and 1 lone
pairs?

A

Pyramidal
107°

38
Q

What is the shape, diagram
and bond angle in a shape
with 2 bonded pairs and 2 lone
pairs?

A

Non linear
104.5°

39
Q

By how many degrees does
each lone pair reduce the
bond angle?

A

2.5°

40
Q

Define electronegativity

A

The ability of an atom to attract the pair
of electrons (the electron density) in a
covalent bond

41
Q

In which direction of the
periodic table does
electronegativity increase?

A

Top right, towards fluorine

42
Q

What does it mean when the
bond is non-polar?

A

The electrons in the bond are evenly
distributed

43
Q

What is the most
electronegative element?

A

Fluorine

44
Q

How is a polar bond formed?

A

Bonding atoms have different
electronegativities

45
Q

Why is H2O polar, whereas
CO2
is non polar?

A

CO2 is a symmetrical molecule, so there
is no overall dipole

46
Q

What is meant by
intermolecular force?

A

Attractive force between neighbouring
molecules

47
Q

What are the 2 types of
intermolecular forces?

A

● Hydrogen bonding
● dipole dipole
● dispersion

48
Q

What is the strongest type of
intermolecular force?

A

Hydrogen bonding

49
Q

What are the 2 interactions
that can be referred as Van
der Waals’ forces?

A

● Permanent dipole - induced dipole
interaction
● Permanent dipole - permanent dipole
interaction

50
Q

Describe permanent dipole-induced dipole interactions

A

● When a molecule with a permanent dipole is
close to other non polar molecules it causes
the non polar molecule to become slightly
polar leading to attraction

50
Q

Describe permanent dipolepermanent dipole interactions

A

Some molecules with polar bonds have
permanent dipoles → forces of attraction
between those dipoles and those of
neighbouring molecules

51
Q

Describe London forces

A

● induced dipole-induced dipole attraction
● London forces are caused by random movements of
electrons
● This leads to instantaneous dipoles
● Instantaneous dipole induces a dipole in nearby
molecules
● Induced dipoles attract one another

52
Q

Are London forces greater in
smaller or larger molecules?

A

Larger due to more electrons

53
Q

Does boiling point increase or
decrease down the noble gas
group? Why?

A

Boiling point increases because the
number of electrons increases and
hence the strength of London forces also
increases

54
Q

What conditions are needed
for hydrogen bonding to
occur?

A
  • O-H, N-H or F-H bond, lone pair of electrons on O, F, N
  • Because O, N and F are highly electronegative, H nucleus is
    left exposed
  • Strong force of attraction between H nucleus and lone pair of
    electrons on O, N, F
55
Q

Draw a diagram of hydrogen
bonding

A
56
Q

Why is ice less dense than
liquid water?

A

● In ice, the water molecules are arranged in a
orderly pattern. It has an open lattice with
hydrogen bonds.
● In water, the lattice is collapsed and the
molecules are closer together.

57
Q

Why does water have a
melting/ boiling point higher
than expected?

A

Hydrogen bonds are stronger than other
intermolecular forces so extra strength is
required to overcome the forces

Chemistry A-Level (19 decks)

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