Bonding

Question 1

What is ionic bonding?

Answer 1

Electrostatic force of attraction between oppositely charged ions.

Question 2

Which atoms lose electrons and what do they form?

Answer 2

Metal atoms form +ve ions

Question 3

Which atoms gain electrons and what do they form?

Answer 3

Non metal atoms form -ve ions

Question 4

What structure do ionic crystals have?

Answer 4

Giant ionic lattice of ions

Question 5

When is ionic bonding stronger and has higher melting points?

Answer 5

When the ions are smaller and/or have higher charges.

Question 6

Why are positive ions smaller compared to their atoms?

Answer 6

They have one less shell of electrons and the ratio of protons to electrons has increased so there is a greater net force on remaining electrons holding them more closely.

Question 7

Why does the ionic radii increase down a group?

Answer 7

As one goes down a group, the ions have more shells of electrons.

Question 8

What is a covalent bond?

Answer 8

Shared pair of electrons.

Question 9

When does a dative covalent bond form?

Answer 9

When the shared pair of electrons in the covalent bond come from only one of the bonding atoms.

Question 10

What is a dative covalent bond also known as?

Answer 10

A co-ordinate bond.

Question 11

What is a dative covalent bond represented by?

Answer 11

An arrow.

Question 12

What direction does the arrow of the dative covalent bond go?

Answer 12

From the atom that is providing the lone pair to the atom that is deficient.

Question 13

What is metallic bonding?

Answer 13

The electrostatic force of attraction between the positive metal ions and the delocalised electrons.

Question 14

What 3 factors affect the strength of metallic bonding?

Answer 14

Number of protons
Number of delocalised electrons
Size of ion

Question 15

How does the number of protons affect the strength of metallic bonding?

Answer 15

The more protons the stronger the bond.

Question 16

How does the number of delocalised electrons affect the strength of metallic bonding?

Answer 16

The more delocalised electrons the stronger the bond.

Question 17

How does the size of the ion affect the strength of metallic bonding?

Answer 17

The smaller the ion the stronger the bond.

Question 18

Why does Mg have stronger metallic bonding than Na?

Answer 18

In Mg there are more electrons in the outer shell that are released to the sea of electrons. The Mg ion is also smaller and has one more
proton. There is therefore a stronger electrostatic attraction between the positive metal
ions and the delocalised electrons and higher energy is needed to break bonds.

Question 19

What are the two structures of a covalent molecule?

Answer 19

Macromolecular
Simple molecular

Question 20

What is the structure of metallic bonding?

Answer 20

Giant metallic lattice

Question 21

2 examples of an ionic substance?

Answer 21

Sodium chloride
Magnesium oxide

Question 22

3 examples of a simple molecular substance?

Answer 22

Iodine
Carbon Dioxide
Water

Question 23

4 examples of a macromolecular substance?

Answer 23

Silicon
Silicon Dioxide
Graphite
Diamond

Question 24

2 examples of a metallic substance?

Answer 24

Magnesium
Sodium

Question 25

When do you use the words 'molecules' and 'IMF'?

Answer 25

When talking about simple molecular substances.

Question 26

Describe the boiling/melting points of ionic substances.

Answer 26

High because of giant lattice of ions with strong electrostatic forces between oppositely charged ions.

Question 27

Describe the boiling/melting points of simple molecular substances.

Answer 27

Low because of weak IMF forces between molecules (e.g. VDW, H bonds, dipole-dipole)

Question 28

Describe the boiling/melting points of macromolecular structure.

Answer 28

High because of many strong covalent bonds in the structure. It takes a lot of energy to break the many strong bonds.

Question 29

Describe the boiling/melting points of metallic substances.

Answer 29

High because of strong electrostatic forces between positive ions and sea of delocalised electrons.

Question 30

State the solubility in water of ionic substances.

Answer 30

Generally good.

Question 31

State the solubility in water of simple molecular substances.

Answer 31

Generally poor

Question 32

State the solubility in water of macromolecular structures.

Answer 32

Insoluble

Question 33

State the solubility in water of metallic substances.

Answer 33

Insoluble

Question 34

Describe the conductivity when solid of ionic substances.

Answer 34

Poor - ions can't move because they're fixed in lattice.

Question 35

Describe the conductivity when solid of simple molecular substances.

Answer 35

Poor - no ions to conduct and electrons are localised.

Question 36

Describe the conductivity when solid of macromolecular structures.

Answer 36

Diamond and sand - poor because electrons are localised. Graphite - good because there are free delocalised electrons between the layers.

Question 37

Describe the conductivity when solid of metallic substances.

Answer 37

Good - delocalised electrons can move through the structure.

Question 38

Describe the conductivity when molten of ionic substances.

Answer 38

Good - ions can move

Question 39

Describe the conductivity when molten of simple molecular substances.

Answer 39

Poor - no ions

Question 40

Describe the conductivity when molten of macromolecular structures.

Answer 40

Poor

Question 41

Describe the conductivity when molten of metallic substances.

Answer 41

Good

Question 42

Describe the general description of ionic substances.

Answer 42

Crystalline solids.

Question 43

Describe the general description of simple molecular substances.

Answer 43

Mostly gases and liquids

Question 44

Describe the general description of macromolecular structures.

Answer 44

Solids

Question 45

Describe the general description of metallic substances.

Answer 45

Shiny metals. Malleable as the positive ions in the lattice are all identical. The ions can slide easily over one another.

Question 46

Name of a molecule with 2 b.p and 0 l.p.

Answer 46

Linear

Question 47

What is the bond angle of a linear molecule?

Answer 47

180

Question 48

Name of a molecule with 3 b.p and 0 l.p.

Answer 48

Trigonal planar

Question 49

What is the bond angle of a trigonal planar molecule?

Answer 49

120

Question 50

Name of a molecule with 4 b.p and 0 l.p.

Answer 50

Tetrahedral

Question 51

What is the bond angle of a tetrahedral molecule?

Answer 51

109.5

Question 52

Name of a molecule with 5 b.p and 0 l.p.

Answer 52

Trigonal bypyramidal.

Question 53

What is the bond angle of a trigonal bypramidal molecule?

Answer 53

120 and 90

Question 54

Name of a molecule with 6 b.p and 0 l.p.

Answer 54

Octahedral

Question 55

What is the bond angle of a octahedral molecule?

Answer 55

90

Question 56

Name of a molecule with 3 b.p and 1 l.p.

Answer 56

Trigonal pyramidal

Question 57

What is the bond angle of a trigonal pyramidal molecule?

Answer 57

107

Question 58

Name of a molecule with 2 b.p and 2 l.p.

Answer 58

Bent

Question 59

What is the bond angle of a bent molecule?

Answer 59

104.5

Question 60

How do you explain the shape of a molecule?

Answer 60

1. State number of bonding pairs and lone pairs of electrons. 2. State that electron pairs repel and try to get as far apart as possible (or to a position of minimum repulsion.) 3. If there are no lone pairs state that the electron pairs repel equally 4. If there are lone pairs of electrons, then state that lone pairs repel more than bonding pairs. 5. State actual shape and bond angle.

Question 61

How much should you reduce bond angles per lone pair?

Answer 61

2.5 degrees

Question 62

Bond angle of square planar?

Answer 62

90

Question 63

What is electronegativity?

Answer 63

Power of an atom to attract a pair of electrons in a covalent bond.

Question 64

What are the most electronegative elements?

Answer 64

F O N Cl

Question 65

What is the most electronegative element?

Answer 65

Fluorine

Question 66

What is electronegativity measured by?

Answer 66

Pauling scale

Question 67

What is the electronegativity of fluorine?

Answer 67

4.0

Question 68

What factors affect electronegativity?

Answer 68

Increases across a period as the number of protons increases and the atomic radius decreases because the electrons in the same shell are pulled in more. Decreases down a group because atomic radius increases and shielding of inner electrons increases.

Question 69

What is a compound containing elements of similar electronegativity and hence a small electronegativity difference?

Answer 69

Covalent

Question 70

What is a compound containing elements of very different electronegativity and hence a very large electronegativity difference (> 1.7)?

Answer 70

Ionic

Question 71

When does a permanent dipole bond form?

Answer 71

When the elements in the bond have different electronegativities (of around 0.3 to 1.7).

Question 72

What is represented by an element with a larger electronegativity?

Answer 72

Slightly negative.

Question 73

What does a permanent dipole bond have?

Answer 73

An unequal distribution of electrons in the bond and produces a charge separation (dipole). This creates the slightly positive and slightly negative ends.

Question 74

What is a symmetric molecule?

Answer 74

Identical bonds and no lone pairs.

Question 75

Can a symmetrical molecule be polar? Why?

Answer 75

No because the individual dipoles on the bonds ‘cancel out’ due to the symmetrical shape of the molecule. There is no net dipole moment: the molecule is non-polar.

Question 76

Where do van der waal forces occur and not occur?

Answer 76

Occur between all molecular substances and noble gases. Don't occur in ionic substances.

Question 77

What factors affect VDW forces?

Answer 77

The more electrons there are in the molecule, the higher the chance of a temporary dipole forming. This makes the VDW forces stronger between the molecules so boiling point will be greater.

Question 78

How can the increasing boiling points of the alkane homologous series be explained?

Answer 78

The increasing number of electrons in the bigger molecules causing an increase in the size of the Van der Waals between molecules.

Question 79

How can the shape of molecules have an affect on the size of the VDW forces?

Answer 79

Long chain alkanes have a larger surface area of contact between molecules for Van der Waals to form than compared to spherical shaped branched alkanes and so have stronger Van der Waals.

Question 80

When do permanent dipole-dipole forces occur?

Answer 80

Between polar molecules

Question 81

Why do the compounds with permanent dipole-dipole forces have higher melting points than those with VDW forces?

Answer 81

Permanent dipole-dipole forces are stronger than VDW

Question 82

Describe a polar molecule.

Answer 82

Polar molecules are asymmetrical and have a bond where there is a significant difference in electronegativity between the atoms.

Question 83

Can permanent dipole-dipole forces occur in addition to VDW Forces?

Answer 83

Yes

Question 84

When does hydrogen bonding occur?

Answer 84

In a compound that has a hydrogen atom attached to nitrogen, oxygen of fluorine - the three most electronegative elements - which must have an available lone pair of electrons.

Question 85

Can hydrogen bonding occur with VDW forces?

Answer 85

Yes

Question 86

Order of strength of the 3 intermolecular bonding?

Answer 86

Hydrogen bonding Permanent dipole dipole forces Van der Waal forces