Bonding and Structure

Question 1

What are ions

Answer 1

Charged particles that is formed when an atom loses or gains electrons

Question 2

What is the charge of the ion
when electrons are gained?

Answer 2

Negative

Question 3

What are molecular ions

Answer 3

Covalently bonded atoms that lose or
gain electrons

Question 4

Which electrons are lost when
an atom becomes a positive
ion

Answer 4

Which electrons are lost when
an atom becomes a positive
ion

Question 5

Do metals usually gain or lose
electrons

Answer 5

Lose electrons

Question 6

Which are the 4 elements that
don’t tend to form ions and
why?

Answer 6

beryllium, boron, carbon
and silicon

Requires a lot of energy to transfer outer shell
electrons

Question 7

What are the 3 main types of
chemical bonds

Answer 7

Ionic
Covalent
Metallic

Question 8

Define ionic bonding

Answer 8

The electrostatic attraction between
oppositely charged ions

Question 9

What determines the
strength of an ionic bond

Answer 9

Ionic radius and ionic charge
- Ionic bonding is stronger and the melting points
higher when the ions are smaller and/ or have
higher charges.

Question 10

Explain the trend in ionic
radius down a group

Answer 10

Increase:
down the group the ions have more shells of electrons ;
outermost electron experience less pull from positive nucleus.

Question 11

What is the trend in isoelectronic ions

Answer 11

Decreases in threes from group 7-5 then gap for G8 then Decreases from Groups 1-3.

Because the electrons are the same and more protons:
The nuclear attraction between outermost electrons and nucleus increases; ions get smaller.

Question 12

What are the physical
properties of ionic
compounds

Answer 12

-high melting points
*non conductor of electricity when solid
*conductor of electricity when in solution or molten
*brittle

Question 13

What happens when a solution of / molten ionic substance is connected to electrodes

Answer 13

Positive ion migrates to negative electrode
Negative ion migrates to positive electrode

Question 14

Define covalent bonding

Answer 14

Electrostatic attraction between two nuclei and their shared
pair of electrons

Question 15

Define metallic bonding

Answer 15

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

Question 16

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

Answer 16

Outer shell

Question 17

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

Answer 17

Solid state- ions are fixed in postions can cannot move

When they are in liquid state the ions are mobile
and can freely carry the charge

Question 18

Giant ionic lattices have high or low melting and boiling point

Answer 18

High

large amount of energy required to overcome the electrostatic bonds

Question 19

In what type of solvents do ionic lattices dissolve

Answer 19

Polar solvents
E.g water

Question 20

Why are ionic compounds soluble in water

Answer 20

Why are ionic compounds soluble in water?
Water has a polar bond. Hydrogen atoms
have a positive charge and oxygen atoms have a 2- charge.
These charges are able to attract charged ions

Question 21

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

Answer 21

Single

Question 22

How many covalent bonds does carbon form

Answer 22

4

Question 23

How many covalent bondsdoes oxygen form

Answer 23

2

Question 24

How many covalent bonds does oxygen form

Answer 24

Double / Triple bonds exert greater electron density
therefore
The attraction between nucleus and electron is greater resuling in a shorter and stronger bond

Question 25

What is a lone pair

Answer 25

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

Question 26

What is formed when atoms share two pairs of electrons

Answer 26

Double bond

Question 27

What is formed when atoms share three pairs of electrons

Answer 27

Triple Bond

Question 28

What is a dative covalent bond

Answer 28

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

Question 29

How are oxonium ions formed

Answer 29

When acid added to water : H30+

Question 30

What does expansion of the octet mean

Answer 30

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

Question 31

What are the types of covalent structure

Answer 31

● Simple molecular lattice ● Giant covalent lattice

Question 32

Describe the bonding in simple molecular structures

Answer 32

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

Question 33

Why do simple molecular structures have low melting and boiling point

Answer 33

Small amount of energy is enough to overcome the intermolecular forces

Question 34

Can simple molecular structures conduct electricity

Answer 34

No - No free mobile charged particles

Question 35

Simple molecular structures dissolve in what type of solvent

Answer 35

Non Polar

Question 36

Give examples of giant covalent structures

Answer 36

Diamond Carbon dioxide, SiO2

Question 37

List some properties of giant covalent structures?

Answer 37

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

Question 38

How does graphite conduct electricity

Answer 38

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

Question 39

Why do giant covalent structures have high melting and boiling point

Answer 39

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

Question 40

describe the structure of a diamond

Answer 40

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

Question 41

What does the shape of a molecule depend on

Answer 41

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

Question 42

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

Answer 42

Linear 180

Question 43

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

Answer 43

Trigonal Planar 120

Question 44

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

Answer 44

Tetrahedral 109.5

Question 45

What is the shape, diagram and bond angle in a shape with 5 bonded pairs and 0 lone pairs

Answer 45

Trigonal bipyramid 90 and 120

Question 46

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

Answer 46

Octahedral 90

Question 47

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

Answer 47

Pyramidal 107

Question 48

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

Answer 48

bent 104.5

Question 49

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

Answer 49

-2.5

Question 50

electronegativity

Answer 50

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

Question 51

What scale is electronegativity measured on?

Answer 51

Pauling

Question 52

In which direction of the periodic table does electronegativity increase

Answer 52

Top Right towards F

Question 53

What does it mean when the bond is non-polar

Answer 53

The electrons in the bond are evenly distributed

Question 54

What is the most electronegative element

Answer 54

F

Question 55

How is a polar bond formed

Answer 55

Bonding atoms have different electronegativities (0.4-1.7)

Question 56

Why is H2O polar, whereas CO 2 is non polar?

Answer 56

CO2 is symmetrical molecule, so there is no overall dipole

Question 57

What is meant by intermolecular force

Answer 57

Attractive force between neighbouring molecules

Question 58

What are the 3 types of intermolecular forces

Answer 58

● Hydrogen bonding ● Permanent dipoles ● London forces

Question 59

Describe permanent dipole- induced dipole interactions

Answer 59

When a molecule with a permanent dipole is close to other non polar molecules the non polar molecule becomes slightly polar leading to attraction

Question 60

Describe permanent dipole-permanent dipole interactions

Answer 60

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

Question 61

Describe London forces

Answer 61

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

Question 62

Are London forces greater in smaller or larger molecules

Answer 62

Larger due to more electrons

Question 63

Does boiling point increase or decrease down the noble gas group? (London Forces)

Answer 63

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

Question 64

What conditions are needed for hydrogen bonding to occur

Answer 64

Hydrogen bonded to either H, N or F and lone pair of electrons on O, F , N

Question 65

Explanation of H bonds

Answer 65

O N and F are highly electronegative: H nucleus exposed Strong force of attraction between H nucleus and lone pair of electrons on O N F

Question 66

Why is ice less dense than liquid water

Answer 66

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

Question 67

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

Answer 67

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

Question 68

What type of intermolecular forces do alkanes have Why

Answer 68

London force → induced dipole-dipole interation Because bonds are nonpolar

Question 69

What happens to the boiling point as alkane chain length increases Why

Answer 69

The boiling point increases: more surface area and so more number of induced dipole- dipole interaction more energy required to overcome the attraction

Question 70

Does a branched molecule have lower or higher boiling point compared to equivalent straight chain Why?

Answer 70

The branched molecule has a lower boiling point they have fewer surface area less induced dipole -dipole interactions.

Question 71

Are alkanes soluble in water? Why?

Answer 71

Insoluble H bonds in water are stronger than alkanes' London forces

Question 72

What kind of intermolecular forces do alcohols have? Why?

Answer 72

Hydrogen bonding Due to the electronegativity difference in the OH bonds

Question 73

How do alcohols’ melting point and boiling point compare to other hydrocarbons’ of similar C chain lengths? Why?

Answer 73

Higher, Because they have hydrogen bonding

Question 74

Are alcohols soluble in water?

Answer 74

Soluble when short chain Insoluble when long chain

Question 75

Why does solubility depend on chain length in alcohols

Answer 75

Short chain- soluble. OH hydrogen bonds to hydrogen bond in water Insoluble when long chain- non polarity of C-H takes precedence

Question 76

Describe trend of boiling temps of H halides F- I

Answer 76

Decreases from HF to Hcl then increases. HF hydrogen bonds- very high HCl- HBr- HI increasing london forces

Question 78

What is a sigma bond

Answer 78

The end to end overlap of atomic orbitals

Question 79

What is a pi bond

Answer 79

The sideways overlap of adjacent p orbitals Above and below the plane of the sigma bond.