Bonding physical chemistry

Question 1

What forces hold the positive ions and negative ions together in ionic compounds

Answer 1

Electrostatic forces

Question 2

What is a molecule

Answer 2

A group of atoms held together by covalent

Question 3

Within a molecule how are covalent bond within atoms held together

Answer 3

By electrostatic attraction that occurs between the nuclei and the shared electrons

Question 4

What are the 3 types of bonding

Answer 4

Ionic
Covalent
Metallic

Question 5

What is a double bone

Answer 5

When four electrons are shared

Question 5

Why do substances composed of molecules (solids,liquid, gas) have low melting points

Answer 5

This is due to the weak attraction between molecules so not a lot of energy is needed to separate them

Question 6

Why do substances composed of molecules (solids,liquid, gas) have low melting points

Answer 6

This is due to the weak attraction between molecules so not a lot of energy is needed to separate them

Question 7

Why are molecules poor conductors of electricity

Answer 7

As they are neutral due to them not having any charged particles

Question 8

What is dative covalent bonding

Answer 8

It’s when in covalent bond one atom will supply both electrons

Question 9

What must happen for dative covalent bonding to occur

Answer 9

The atom supplying the electrons has a lone pair of electrons and has a full outer shell

The atom receiving the electrons is electron efficient and dosent have a filled outer shell

Question 10

What is a lone pair of electrons

Answer 10

Electrons that aren’t involved in the covalent bond

Question 11

On a diagram how are dative covalent bonds represented

Answer 11

By an arrow

Question 12

What is the structure of metals

Answer 12

It’s positive ions which form a lattice and they exist in a sea of delocalised electrons

Question 13

In metals what do the outer layers of atoms do

Answer 13

The outer layers of atoms merge

Question 14

What is the amount of deloclasied electrons dependant on

Answer 14

The amount of deloclasied electrons is dependant on the amount of electrons lost by each metal atom

Question 15

Why do metals contain such large structures

Answer 15

As the metallic bonding spreads throught the metal

Question 16

Name the properties of metals

Answer 16

Strong
High melting points
Malleable
Good conductors of heat and electricity

Question 17

Why are metals such good conductors of heat

Answer 17

The sea of electrons have high thermal conductivites

The ions are closely packed together so when heated they vibrate vigrously and enegry spreads throughout the metal as a result

Question 18

What does the strength of the metallic bond dependant on

Answer 18

The size of the ion and it’s charge

Question 19

How does the charge of the ion make metallic bond strong

Answer 19

As it means that there are more deloclasied electrons and so a stronger electrostatic attraction occurs between the ions and electrons

Question 20

How does ion size make a strong metallic bond

Answer 20

If the ion size is smaller the electrons become closer to the positive nucleus and this makes the bond stronger

Question 21

What two things within a metal gives it a high boiling point and melting point

Answer 21

It’s has a large structure and the

strong attraction between the metal ions and the electrons

Question 22

What does ductile mean

Answer 22

Layers slide over each other

Question 23

What is Electro negativity

Answer 23

The power of an atom to attract electron density in a covalent bond to it’s self

Question 24

What factors effect electron negativity

Answer 24

Nuclear charge The shielding of nuclear charge by electron in it's inner shell The distance between the nucleus and the outer shell of electrons

Question 25

Why does electron negativity increase across a period

Answer 25

This is because the nuclear charge increases so the attraction of the nucleus to the outer shells is strong

Question 26

Going up a group why does electron negativity increase

Answer 26

This is due to there being less shielding From the inner electrons as the atoms gets smaller

Question 27

What is polarity of a covalent bond

Answer 27

It's when atoms that are bonded covalently have unequal distributed number of electrons

Question 28

What are polar covalent bonds

Answer 28

When atoms are bond covalently have an uneven distribution of electrons

Question 29

What can Increase the polarity of covalent bonds

Answer 29

The greater the difference in electro negativity

Question 30

When two different atoms are bonded covalently how are the electrons spread

Answer 30

They spread to the atom that is most electronegative

Question 31

What are the 3 types of intermolecular bonds

Answer 31

Van der vaals Dipole-dipole Hydrogen bond

Question 32

Name in order of strength of each bond

Answer 32

Hydrogen bond Dipole - dipole Van der waals

Question 33

What is polarity

Answer 33

The unequal distribution of electron density within a covalent bond between atoms

Question 34

When do dipole dipole forces occur

Answer 34

They occur between molecules that contain permeant dipoles

Question 35

What are van der waals forces

Answer 35

They are small very weak electrostatic attractions that occur between molecules and atoms

Question 36

What causes van der waals forces to occur

Answer 36

Positive and negative charges that make up all atoms and molecules

Question 37

Although neutral why may a dipole occur in a atom

Answer 37

As a result of electrons constantly moving around it causes the distribution of charge to change

Question 38

How is the dipole a temporary one

Answer 38

As the electrons are always changing direction the dipole does as well and so when a dipole occurs it's only instant and temporary

Question 39

What affect does a dipole occurring in one atom have on surrounding atoms

Answer 39

It has an effect on electron distribution of the nearby surrounding atoms and so they become attracted to the original atom

Question 40

What has the original atom caused in the nearby atoms

Answer 40

It had induced dipoles

Question 41

When electron disturbution in the original atom has changed what effect does it have on the other atoms

Answer 41

It will induce new dipoles in the surrounding atoms and these new dipoles become attracted to the original atom

Question 42

What is the attraction of the new dipoles to the original atom

Answer 42

Van der waals

Question 43

What happens to van der waals when more electrons are present

Answer 43

They increase in size

Question 44

What conditions are needed for hydrogen bond to take place

Answer 44

Lone pair of electrons Highly electronegative atoms A positively charged hydrogen atom so it attracts the lone pair of electrons

Question 45

What are the 3 electronegative atoms that can bond with hydrogen

Answer 45

Oxygen Fluorine Nitrogen

Question 46

Why do solids expand when heated

Answer 46

This is because when heated the particles in the solid move apart slightly causing the solid to expand

Question 47

What is enthalpy change of melting

Answer 47

The amount of enegry needed to weaken the forces in a solid so it can become a liquid

Question 48

Why does temperature not change when a solid melts

Answer 48

As the heat enegry is being absorbed by the forces in a solid causing it to weaken and then melt

Question 49

What is enthalpy

Answer 49

A measure of the change In Heat under pressure

Question 50

What it's the enthalpy change of vaporisation

Answer 50

The amount of energy needed to break the intermolecular forces between liquid particles so a gas forms

Question 51

What are crystals

Answer 51

They are solids in which there particles are in a regular arrangement and are held by forces of attraction

Question 52

What are the 4 types if crystals

Answer 52

Ionic Metallic Molecular Metallic

Question 53

Describe the structure of ionic crystals

Answer 53

They have strong electrostatic attraction forces as they have oppositely charged ions

Question 54

By having a structure comprised of strong electrostatic forces what property does it give ionic crystals

Answer 54

They have high melting points as a result

Question 55

Describe the structure of metallic crystals

Answer 55

They contain a lattice of positive ions that are surrounded by a sea of deloclasied electrons and they have a strong attraction

Question 56

Describe the structure of molecular crystals

Answer 56

It's a regular arrangement of molecules held together by intermolecular forces

Question 57

How are atoms within the molecules held

Answer 57

They are held by covalent bond

Question 58

Why do molecular crystals have low melting points

Answer 58

As the intermolecular forces between the molecules are very weak

Question 59

What is the structure of macromolecules

Answer 59

The covalent bonds between atoms extends throughout the structure making the molecular larger

Question 60

What two macromolecules are made from carbon

Answer 60

Diamond and graphite

Question 61

Describe the structure of carbon

Answer 61

Each carbon atom forms four covalent bonds throughout the structure of diamond

Question 62

What properties does diamond have a result of it's large structure

Answer 62

It's a hard material | High melting point

Question 63

What two bonds are present in graphite

Answer 63

Covalent and van der waals

Question 64

How is the structure of graphite different to that of diamond

Answer 64

Unlike in diamond graphite froms 3 covalent bonds for each carbon atom

Question 65

Why is graphite able to conduct electricity unlike

Answer 65

It contains an extra electron in each carbon atom so it because deloclasied when carries the charge through

Question 66

Why is graphite so soft

Answer 66

It contains van der waals forces between it's layers so the layers slide over one another

Question 67

What is electron pair reply soon theory

Answer 67

That pairs is electrons around atoms will repel one another

Question 68

Give the order in which repulsion increases between bonding pairs

Answer 68

Bonding pair -bonding pair Lone pair bond pair Lone pair lone pair

Question 69

When a molecule contains two pairs of electrons what is it's shape and bond angle

Answer 69

Linear and 180 because it contains to bond pairs that repel as much as possible

Question 70

When a molecules contains 3 bond pairs and no lone pairs what's it's shape and angle

Answer 70

Trigonal plannar bond angle 120

Question 71

When a molecule has 2 bond pairs and 1 lone pair what's the bond angle

Answer 71

118 and bent line molecule

Question 72

When a molecule contains 4 bonding pairs what's it's shape and bond angle

Answer 72

109.5 and it's a tetrahedral

Question 73

When a molecule has 3 bonding pairs and one lone pair what's it's shape and bond angle

Answer 73

It's a trigonal pyramid and the angle is 107

Question 74

When a molecule contains two bond pairs and two electron pairs what's it's angle and shape

Answer 74

Bent line molecule and the angle is 104.5

Question 75

When a molecule has 5 bond pairs what's it's shape and bond angle

Answer 75

Trigonal bipyramid 120 and 90

Question 76

What is a molecule contains 3 bond pairs and two lone pair what's the angle and shape

Answer 76

The shape is trigonal planar and the bond angle is 120

Question 77

When a molecule contains 6 bond pairs what's the shape and angle

Answer 77

The shape is octahedral and angle is 90

Question 78

When the molecule has 5 bond pairs and 1 lone pair

Answer 78

The shape is square pyramid and the angle is 89

Question 79

When the molecule has two lone Pairs and 4 bond pairs what's the shape and angle

Answer 79

It's a square planar and the angle is 90