Atoms, Bonds and Groups - Electrons, Bonding and Structure Flashcards Preview

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Flashcards in Atoms, Bonds and Groups - Electrons, Bonding and Structure Deck (111):
1

Define the first ionisation energy.

The first ionisation energy of an element is the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.

2

What is the energy needed to form positive ions known as?

The energy needed to form positive ions is known as the ionisation energy.

3

What do ionisation energies provide evidence for?

Ionisation nergies provide evidence for the arrangement of electrons in atomic shells.

4

If there is a large increase between a successive ionisation energy, what could this mean?

Sometimes a large increase in successive ionisation energies will be observed. This is because the electron has been removed from the next shell.

5

Why are electrons in the outer shell removed first?

Electrons in the outer shell are removed first as they have the least attraction to the nucleus.

6

On what three factors does nuclear attraction rely?

Nuclear attraction relies on:

  • atomic radius
  • nuclear charge
  • electron shielding (also known as screening)

7

How does the atomic radius affect nuclear attraction?

The greater the atomic radius, the smaller the nuclear attraction experienced by the outer electrons.

8

How does the nuclear charge affect nuclear attraction?

The greater the nuclear charge, the greater the attractive force on the outer electrons.

9

How does electron shielding affect nuclear attraction?

Shielding reduces the net attractive force from the positive nucleus on the outer shell electrons.

10

Define eledtron shielding.

Electron shielding is the repulsion between electrons in different inner shells. The more inner shells there are the larger the shielding effect.

11

Define successive ionisation energies.

Successive ionisation energies are a measure of the energy required to remove each electron in turn.

12

Define the second ionisation energy.

The second ionisation energy of an element is the energy required to remove one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.

13

How many ionisation energies does each element have?

Each element has as many ionisation energies as it has electrons.

14

TRUE or FALSE

Each successive ionisation energy is smaller than the one before?

FALSE!

Each successive ionisation energy is larger than the one before.

15

Define a shell.

A shell is a group of atomic orbitals with the same principal quantum number, n. Also known as a main energy level.

16

Define the principle quantum number, n.

The principle quantum number, n, is a number representing the relative overall energy of each orbital, which increases with distance from the nucleus. The sets of orbitals with the same n-value are referred to as electron shells or energy levels.

17

TRUE or FALSE

The larger the value of n the further the shell from the nucleus.

TRUE!

The larger the value of n, the further the shell from the nucleus.

18

How many electrons can be held in the first shell?

The first shell can hold 2 electrons.

19

How many electrons can the second shell hold?

The second shell can hold 8 electrons.

20

How many electrons can the third shell hold?

The third shell can hold 18 electrons.

21

How many electrons can the fourth shell hold?

The fourth shell can hold 32 electrons.

22

What is the 'rule' to work out how many electrons each shell can hold?

Each shell can hold up to 2n2 electrons.

23

Define atomic orbitals.

An atomic orbital is a region within an atom that can hold up to two electrons, with opposite spins. Each shell in comprised of atomic orbitals. There are four different types of orbitals.

24

What are the four different types of atomic orbitals?

The four different types of atomic orbitals are: s, p, d and f.

25

What shape is an s orbital?

An s orbital is spherical.

26

How many s orbitals are found in each shell?

Each shell contains one s orbital.

27

What shape are p orbitals?

p orbitals have a 3D dumbbell shape.

28

How many p orbitals are in each shell?

From n=2 upwards, each shell contains 3 p orbitals.

29

How many d orbitals are found in each shell?

From n=3 upwards, each shell contains 5 d orbitals.

30

How many f orbitals are found in each shell?

From n=4 upwards, each shell contains 7 f orbitals.

31

TRUE or FALSE

Electrons occupying the same atomic orbital must have the same spin?

FALSE!

Each of the electrons in an orbitals must have opposite spins.

32

Define a sub-shell.

A sub-shell is a group of the same type of atomic orbitals (s, p, d, f) within a shell.

33

In what order do the sub-shell energies increase?

s < p < d < f

34

What are the set of rules to determine the electron configuration sometimes also known as?

The rules used to figure out electron configuration are also sometimes known as the Aufbau principle.

35

What are the rules to determine electron configuration?

  • electrons are added, one at a time, to 'build up' the atom
  • the lowest available energy level is filled first
  • each energy level must be full before the next, higher, energy level starts to fill
  • when a sub-shell is built up with electrons, each orbital is filled singly before pairing starts

36

Each occupied sub-shell is written in what format?

Each occupied sub-shell is written in the format nxy.

37

When each occuppied sub-shell is written in the format nxy, for what do the n, x and y stand?

n = shell number

x = type of orbital

y = number of electrons in the orbital making up the sub-shell

38

Which energy level is, unexpectedly, below that of the 3d energy level?

The 4s energy level is below that of the 3d energy level, so the 4s energy level fills before the 3d orbitals.

39

When positive ions are formed, from where are electrons removed?

When positive ions are formed, electrons are removed from the highest energy orbitals.

40

When negative ions are formed, where are electrons added to?

When negative ions are formed, electrons are added to the highest energy orbitals.

41

TRUE or FALSE

The 3d electrons are lost before the 4s electrons?

FALSE!

The 4s electrons are lost before the 3d electrons.

42

Only six elements exist naturally as single, unbonded atoms, what are they?

Only six elements exist naturally as single, unbonded atoms, these are the noble gases.

43

Which are the only elements with eight electrons in their outer shells?

The noble gases are the only elements with eight electrons in their outer shells.

44

What is the octet rule?

The tendency to acquire a noble gas electron configuration is referred to as the octet rule.

45

 What is the tendency to acquire a noble gas electron configuration also known as?

The tendency to acquire a noble gas electron configuration is known as the octet rule.

46

In ionic bonding electrons are ............

In ionic bonding, electrons are transfererred.

47

In covalent bonding, electrons are ............

In covalent bonding, electrons are shared between the atoms.

48

What is metallic bonding?

Metallic bonding occurs in metals, electrons are shared between all the atoms.

49

Approximately what percentage of the air is made up of noble gases?

~1% of air is made up of noble gases.

50

Which is the most abundant noble gas?

Argon is the most abundant noble gas with around 30x more argon than CO2 in air.

51

What is helium used for?

Helium is used in air ships.

52

What is neon used for?

Neon is used in signs.

53

What is argon used for?

Argon is used in filament light bulbs.

54

What is krypton used for?

Krypton is used in lasers for eye surgery.

55

What is xenon used for?

Xenon is used in car headlights.

56

Define an ionic bond.

An ionic bond is the electrostatic attraction between oppositely charged ions.

57

What determines the shape of a molecule?

The shape of a molecule or ion is determined by the number of electron pairs in the outer shell surrounding the central atom.

58

What shape molecule will two electron pairs / bonded regions on the central atom produce?

Two bonded regions will produce a linear molecule.

59

What shape molecule will three electron pairs / bonded regions on the central atom produce?

Three bonded regions will produce a trigonal planar molecule.

60

What shape molecule will four electron pairs / bonded regions on the central atom produce?

Four bonded regions on the central atom will produce a molecule which is tetrahedral.

61

What shape molecule will six electron pairs / bonded regions on the central atom produce?

Six bonded regions on the central atom will produce a molecule which is octahedral.

62

TRUE or FALSE

A bonded pair of electrons is slightly more electron dense than a lone pair of electrons?

FALSE!

A lone pair of electrons is slightly more electron dense than a bonded pair of electrons.

63

By approximately how much does each lone pair reduce the bond angle by?

Each lone pair reduces the bond angle by ~2.5o.

64

Define electronegativity.

Electronegativity is a measure of the attraction of a bonded atom for the pair of electrons in a covalent bond.

65

Define a non-polar bond.

A non-polar bond is one in which the electron are evenly distributed between the two atoms (eg H-H).

66

In a non-polar bond, which of the atoms is said to be more electronegative?

The bonding atom with the greater attraction for the electron pair is said to be more electronegative.

67

What is a permanent dipole?

A permanent dipole is a small charge difference across a bond that results from a difference in the electronegativities of the bonded atoms.

68

TRUE or FALSE

A polar covalent bond has a permanent dipole?

TRUE!

A polar covalent bond has a permanent dipole.

69

In 1932 Linus Pauling invented what scale to measure electronegativity?

In 1932 Linus Pauling invented the Pauling scale to measure electronegativity.

70

A small difference in electronegativity of bonded atoms makes what type of bond?

A small difference in electronegativity of bonded atoms results in a polar covalent bond.

71

A large difference in electronegativity of bonded atoms results in what type of bond?

A large difference in electronegativity results in an ionic bond.

72

TRUE or FALSE

At room temperature all ionic compounds are solids?

TRUE!

At room temperature, all ionic compounds are solids.

73

TRUE or FALSE

Intermolecular forces are strong.

FALSE!

Intermolecular forces are weak.

74

What are the three most common types of intermolecular forces?

The three common types of intermolecular forces are:

  • hydrogen bonds
  • permanent dipole-dipole forces
  • van der waals forces

75

What is a permanent dipole-dipole force?

A permanent dipole-dipole force is a weak attractive force between permanent dipole in neighbouring polar molecules.

76

What are van der Waals' forces?

van der Waals' forces are attractive forces between induced dipoles in neighbouring molecules.

77

TRUE or FALSE

van der Waals' forces increase with increasing number of electrons?

TRUE!

van der Waals' forces increase with increasing number of electrons.

78

TRUE or FALSE

Hydrogen bonds are the only forces acting between non-polar molecules?

FALSE!

van der Waals' forces are the only forces acting between non-polar molecules.

79

What is a hydrogen bond / hydrogen bonding?

A hydrogen bond is a strong dipole-dipole attraction between an electron-deficient hydrogen atom on one molecule and a lone pair of electrons on a highly electronegative atom on a different molecule.

80

A hydrogen bond in water has only about .. % of the strength of an O-H bond.

A hydrogen bond in water has only about 5% of the strength of the strength of an O-H bond.

81

TRUE or FALSE

Water is more dense than ice?

TRUE!

Water is more dense than ice (ice is less dense than water).

82

What property of water gives it its relatively high melting and boiling points?

The relatively strong hydrogen bonds in water give it its relatively high melting and boiling points.

83

What property of water gives it its high level of surface tension?

Hydrogen bonds give water a relatively high surface tension.

84

What role do hydrogen bonds play in DNA?

In DNA, hydrogen bonds are responsibly for holding together the double helix structure.

85

What is metallic bonding?

Metallic bonding is the electrostatic attraction between positive metal ions and delocalised electrons.

86

What are the properties of giant metallic lattices?

Giant metallic lattices:

  • high melting / boiling points
  • good conductors of electricity
  • maleable
  • ductile

87

Why do giant metallic lattices have high melting / boiling points?

Giant metallic lattices have high melting / boiling points because of the attraction between positive ions and delocalised electrons is strong.

88

Define ductile.

Ductile means it can be drawn out or stretched. Ductility permits metals to be drawn out into wires.

89

Define maleable.

Malleable means it can be hammered into shape.

90

Why is magnesium oxide used to line furnaces for brick-making?

Magnesium oxide has such a high melting point because of its ionic lattice structure that it can be used to line furnaces for brick-making.

91

TRUE or FALSE

An ionic lattice in its solid state does not conduct electricity?

TRUE!

An ionic lattice in its solid state is a non-conductor of electricity.

92

When does an ionic lattice conduct electricity?

When an ionic compound is melted or dissolved in water the solid breaks down and the ions are free to move making it an electrical conductor.

93

What is a simple molecular lattice?

A simple molecular lattice is a three-dimensional structure of molecules, bonded together by weak intermolecular forces.

94

What are the properties of simple molecular lattices?

Simple molecular lattices:

  • low melting and boiling point
  • non-conductors of electricity
  • soluble in non-polar solvents (eg hexane)

95

What is a giant covalent lattice?

A giant covalent lattice is a three-dimensional structure of atoms, bonded together by strong covalent bonds.

96

What are examples of giant covalent lattices?

Graphite and diamond

97

What are the properties of giant covalent lattices?

Properties of giant covalent lattices:

  • high melting and boiling points
  • non-conductors of electricity
  • insoluble in both polar and non-polar solvents

98

Why are giant covalent lattices generally non-conductors of electricity?

Giant covalent lattices are non-conductors of electricity because there are no free charged particles (except in graphite).

99

Why are giant covalent lattices insoluble in both polar and non-polar solvents?

Giant covalent lattices are insoluble in both polar and non-polar solvents because the lattice is too strong to break.

100

What is the structure of diamond?

Diamond has a tetrahedral structure held together by strong covalent bonds throughout the lattice.

101

What is the structure of graphite?

Graphite has a strong hexagonal layer structure, but with weak van der Waals' forces between the layers.

102

What is the conductivity of diamond like and why?

Diamond has poor electrical conductivity because there are no delocalised electrons as all outer-shell electrons are used for covalent bonds.

103

What is the conductivity of graphite like and why?

Graphite has good electrical conductivity because there are delocalised electrons between the layers. Electrons are free to move parallel to the layers when a voltage is applied.

104

What is the hardness of diamond like and why?

Diamond is hard because its tetrahedral shape allows external forces to be spread throughout the lattice.

105

What is the hardness of graphite like and why?

Graphite is soft because the bonding within each layer is strong, but the weak forces between layers allow layers to slide easily.

106

What is a dative covalent bond?

A dative covalent or coordinate bond is a shared pair of electrons which has been provided by one of the bonding atoms only.

107

What is the bond angle in a molecule which is tetrahedral?

The bond angle in a molecule which is tetrahedral is 109.5o.

108

What is the bond angle in a molecule which is trigonal planar?

A molecule which is trigonal planar has a bond angle of 120o.

109

What is the bond angle in a molecule which is octahedral?

The bond angle in an octahedral molecule is 90o.

110

What is the bond angle in a pyramidal molecule?

The bond angle in a pyramidal molecule is 107o.

111

What is the bond angle in a non-linear molecule?

The bond angle in a non-linear molecule is 104.5o.