Chemistry Module 2 - Chapter 5 Flashcards

1
Q

What are shells?

A

In an atom, electron shells make up a model that helps us to visualise something that cannot be seen.
1. Shells are regarded as energy levels.
2. The energy increases as the shell number increases.
3. The shell number or energy level is called the principal quantum number n.

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2
Q

What is an atomic orbital?

A

An atomic orbital is a region around the nucleus that can hold up to two electrons, with opposite spins.

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3
Q

How many electrons can be found in the 1st shell?

A

2

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4
Q

How many electrons can be found in the 2nd shell?

A

8

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5
Q

How many electrons can be found in the 3rd shell?

A

18

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6
Q

How many electrons can be found in the 4th shell?

A

32

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7
Q

What subshells can the second shell be split into?

A

2s = contains 2 electrons slightly harder to remove
2p = containing 6 electrons slightly easier to remove.

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8
Q

What are the 4 types of sub-shells?

A

S
P
D
F

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9
Q

How many orbitals do the 4 subshells (S,P,D,F) contain?

A

S = 1
P = 3
D = 5
F = 7

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10
Q

How many electrons can an orbital hold?

A

It can hold 2 in each orbital

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11
Q

How many max electrons doe the four subshells (S,P,D,F) contain?

A

S = 2
P = 6
D = 10
F = 14

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12
Q

What does the s-orbital look like?

A

O (spherical shape)

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13
Q

What does the p-orbital look like?

A

8 (dumbbell shape)

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14
Q

What is the order in which the subshells full up?

A

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p

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15
Q

From which shell onwards is S orbital present?

A

n = 1

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16
Q

From which shell onwards is P orbital present?

A

n = 2

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17
Q

From which shell onwards is D orbital present?

A

n = 3

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18
Q

From which shell onwards is F orbital present?

A

n = 4

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19
Q

What is the filling order in the n=2 shell?

A

2s, 2p

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20
Q

What is the filling order in the n=3 shell?

A

3s, 3p, 3d

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21
Q

What is the filling order in the n=4 shell?

A

4s, 4p, 4d, 4f

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22
Q

What is the Aufbau Principle?

A

Electrons always occupy the lowest energy sub-levels first.

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23
Q

Why does the 4s orbital fill before the 3d orbital?

A

4s orbital has a lower energy than 3d before it is filled.

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24
Q

How is the noble gas notation for an atom or ion deduced?

A
  1. The symbol of the noble gas from the previous period is written in square brackets.
  2. This represents the electronic structure of the noble gas.
  3. The rest of the electronic structure is written next to it.
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25
Q

What are the 3 main types of chemical bonds?

A
  1. Ionic
  2. Covalent
  3. Metallic
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26
Q

What is ionic bonding?

A

Ionic bonding is the electrostatic attraction between positive and negative ions. It holds together cations (positive ions) and anions (negative ions) in ionic compounds.

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27
Q

Give an example of an ionically bonded substance.

A

NaCl (Sodium Chloride - salt)

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28
Q

How are ions found in ionic compounds? What does this form?

A

Although it is convenient to look at ionic bonding acting between a small number of ions, each ion attracts oppositely charged ions in all directions.

The result is a giant ionic lattice structure containing billions of billions of ions.

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29
Q

Define covalent bonding.

A

Attraction between a shared pair of electrons and the nuclei.

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30
Q

Define metallic bonding.

A

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

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31
Q

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

A

The outer shell.

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32
Q

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

A

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

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33
Q

Do Giant IOnic lattices have a high or low melting and boiling point?

A

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

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34
Q

In what types of solvents do ionic lattices dissolve?

A

Polar solvents (e.g., water)

35
Q

Why are ionic compounds soluble in water?

A

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

36
Q

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

A

Single bond.

37
Q

How many covalent bonds does carbon form?

A

4

38
Q

How many covalent bonds does oxygen form?

A

2

39
Q

What is a lone pair?

A

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

40
Q

What is formed when atoms share two pairs of electrons?

A

Double bond.

41
Q

What is formed when atoms share three pairs of electrons?

A

Triple bond.

42
Q

What is average bond enthalpy?

A

Measure of average energy needed to break the bond.

43
Q

What is a dative covalent bond?

A

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

44
Q

How are oxonium ions formed?

A

Formed when acid is added to water, H3O(+)

45
Q

What does expansion of the octet mean?

A

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

46
Q

What are the types of covalent structure?

A
  1. Simple molecular lattice.
  2. Giant covalent lattice.
47
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.

48
Q

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

A

Small amount of energy si enough to overcome the intermolecular forces.

49
Q

Can simple molecular structures conduct electricty?

A

No, they are non conductors.

50
Q

Why do simple molecular structures not conduct electricty?

A

They have no free-charged particles to move around.

51
Q

Simple molecular structures dissolve in what type of solvent?

A

Non-polar solvents.

52
Q

Give examples of giant covalent structures.

A
  1. Diamond
  2. Silicon dioxide (SiO2)
  3. Graphite
53
Q

List some properties of giant covalent structures (3).

A
  1. High melting and boiling point.
  2. Non-conductors of electricity, except graphite.
  3. Insoluble in polar and non-polar solvents.
54
Q

How does graphite conduct electricity?

A

Delocalised electrons present between the layers can move freely carrying the charge.

55
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.

56
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.

57
Q

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

A

Linear
180°
–*

58
Q

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

A

Trigonal planner
120°

59
Q

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

A

Tetrahedral
109.5°

60
Q

What is the shape, and bond angle in a shape with 5 bonding pairs, and 0 lone pairs?

A

Trigonal bipyramid
90° and 120°

61
Q

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

A

Octahedral
90°

62
Q

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

A

Pyramidal
107°

63
Q

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

A

Non-linear
104.5°

64
Q

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

A

2.5°

65
Q

Define electronegativity.

A

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

66
Q

In what direction of the periodic table, does electronegativity increase?

A

Top right, towards flourine

67
Q

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

A

The electrons in the bond are evenly distributed.

68
Q

What is the most electronegative element?

A

Flourine.

69
Q

How is a polar bond formed?

A

Bonding atoms have different electronegativities.

70
Q

Why is H2O polar, whereas CO2, is non-polar?

A

CO2 is a symmetrical molecules, so there is no overall dipole.

71
Q

What is meant by intermolecular force?

A

Attractive force between neighbouring molecules.

72
Q

What are the 2 types of intermolecular forces?

A
  1. Hydrogen bonding.
  2. Van der Waals’ forces.
73
Q

What is the strongest type of intermolecular force?

A

Hydrogen bonding.

74
Q

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

A
  1. Permanent dipole - induced dipole interaction.
  2. Permanent dipole - permanent dipole interaction.
75
Q

Describe Permanent dipole - induced dipole interaction.

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.

76
Q

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

A
  1. Permanent dipole - induced dipole interaction.
  2. Permanent dipole - permanent dipole interaction.
77
Q

Describe Permanent dipole - permanent dipole interaction.

A

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

78
Q

Describe London forces.

A
  1. London forces are caused by random movements of electrons.
  2. This leads to instantaneous dipoles.
  3. Instantaneous dipole induced a dipole in nearby molecules.
  4. Induces dipoles attract one another.
79
Q

Are London forces greater in smaller or larger molecules?

A

Larger due to more electrons.

80
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.

81
Q

What conditions are needed for hydrogen bonding to occur?

A

O-H, N-H, or F-H bond, lone pairs of electrons on O, F, N, because O, N, F, are highly electronegative.

H nucleus is left exposed.

A strong force of attraction between the H nucleus and a lone pair of electrons on O, N, and F.

82
Q

Why is ice less dense than liquid water?

A
  1. In ice, the water molecules are arranged in an orderly pattern. It has an open lattice with hydrogen bonds.
  2. In water, the lattice collapses and the molecules are closer together.
83
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.