Bonding physical chemistry Flashcards

1
Q

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

A

Electrostatic forces

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2
Q

What is a molecule

A

A group of atoms held together by covalent

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3
Q

Within a molecule how are covalent bond within atoms held together

A

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

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4
Q

What are the 3 types of bonding

A

Ionic
Covalent
Metallic

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5
Q

What is a double bone

A

When four electrons are shared

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5
Q

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

A

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

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6
Q

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

A

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

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7
Q

Why are molecules poor conductors of electricity

A

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

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8
Q

What is dative covalent bonding

A

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

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9
Q

What must happen for dative covalent bonding to occur

A

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

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10
Q

What is a lone pair of electrons

A

Electrons that aren’t involved in the covalent bond

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11
Q

On a diagram how are dative covalent bonds represented

A

By an arrow

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12
Q

What is the structure of metals

A

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

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13
Q

In metals what do the outer layers of atoms do

A

The outer layers of atoms merge

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14
Q

What is the amount of deloclasied electrons dependant on

A

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

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15
Q

Why do metals contain such large structures

A

As the metallic bonding spreads throught the metal

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16
Q

Name the properties of metals

A

Strong
High melting points
Malleable
Good conductors of heat and electricity

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17
Q

Why are metals such good conductors of heat

A

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

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18
Q

What does the strength of the metallic bond dependant on

A

The size of the ion and it’s charge

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19
Q

How does the charge of the ion make metallic bond strong

A

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

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20
Q

How does ion size make a strong metallic bond

A

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

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21
Q

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

A

It’s has a large structure and the

strong attraction between the metal ions and the electrons

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22
Q

What does ductile mean

A

Layers slide over each other

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23
Q

What is Electro negativity

A

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

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24
Q

What factors effect electron negativity

A

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

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25
Q

Why does electron negativity increase across a period

A

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

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26
Q

Going up a group why does electron negativity increase

A

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

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27
Q

What is polarity of a covalent bond

A

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

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28
Q

What are polar covalent bonds

A

When atoms are bond covalently have an uneven distribution of electrons

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29
Q

What can Increase the polarity of covalent bonds

A

The greater the difference in electro negativity

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30
Q

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

A

They spread to the atom that is most electronegative

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31
Q

What are the 3 types of intermolecular bonds

A

Van der vaals
Dipole-dipole
Hydrogen bond

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32
Q

Name in order of strength of each bond

A

Hydrogen bond
Dipole - dipole
Van der waals

33
Q

What is polarity

A

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

34
Q

When do dipole dipole forces occur

A

They occur between molecules that contain permeant dipoles

35
Q

What are van der waals forces

A

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

36
Q

What causes van der waals forces to occur

A

Positive and negative charges that make up all atoms and molecules

37
Q

Although neutral why may a dipole occur in a atom

A

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

38
Q

How is the dipole a temporary one

A

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

39
Q

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

A

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

40
Q

What has the original atom caused in the nearby atoms

A

It had induced dipoles

41
Q

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

A

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

42
Q

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

A

Van der waals

43
Q

What happens to van der waals when more electrons are present

A

They increase in size

44
Q

What conditions are needed for hydrogen bond to take place

A

Lone pair of electrons

Highly electronegative atoms

A positively charged hydrogen atom so it attracts the lone pair of electrons

45
Q

What are the 3 electronegative atoms that can bond with hydrogen

A

Oxygen
Fluorine
Nitrogen

46
Q

Why do solids expand when heated

A

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

47
Q

What is enthalpy change of melting

A

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

48
Q

Why does temperature not change when a solid melts

A

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

49
Q

What is enthalpy

A

A measure of the change In Heat under pressure

50
Q

What it’s the enthalpy change of vaporisation

A

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

51
Q

What are crystals

A

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

52
Q

What are the 4 types if crystals

A

Ionic
Metallic
Molecular
Metallic

53
Q

Describe the structure of ionic crystals

A

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

54
Q

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

A

They have high melting points as a result

55
Q

Describe the structure of metallic crystals

A

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

56
Q

Describe the structure of molecular crystals

A

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

57
Q

How are atoms within the molecules held

A

They are held by covalent bond

58
Q

Why do molecular crystals have low melting points

A

As the intermolecular forces between the molecules are very weak

59
Q

What is the structure of macromolecules

A

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

60
Q

What two macromolecules are made from carbon

A

Diamond and graphite

61
Q

Describe the structure of carbon

A

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

62
Q

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

A

It’s a hard material

High melting point

63
Q

What two bonds are present in graphite

A

Covalent and van der waals

64
Q

How is the structure of graphite different to that of diamond

A

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

65
Q

Why is graphite able to conduct electricity unlike

A

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

66
Q

Why is graphite so soft

A

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

67
Q

What is electron pair reply soon theory

A

That pairs is electrons around atoms will repel one another

68
Q

Give the order in which repulsion increases between bonding pairs

A

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

69
Q

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

A

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

70
Q

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

A

Trigonal plannar bond angle 120

71
Q

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

A

118 and bent line molecule

72
Q

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

A

109.5 and it’s a tetrahedral

73
Q

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

A

It’s a trigonal pyramid and the angle is 107

74
Q

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

A

Bent line molecule and the angle is 104.5

75
Q

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

A

Trigonal bipyramid 120 and 90

76
Q

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

A

The shape is trigonal planar and the bond angle is 120

77
Q

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

A

The shape is octahedral and angle is 90

78
Q

When the molecule has 5 bond pairs and 1 lone pair

A

The shape is square pyramid and the angle is 89

79
Q

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

A

It’s a square planar and the angle is 90