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Chemistry AQA A-Level > Bonding (Not finished) > Flashcards

Bonding (Not finished) Flashcards

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1
Q

What are ionic bonds

A

Strong electrostatic forces of attraction between oppositely charged ions

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2
Q

What are covalent bonds

A

Electrostatic force of attraction between a shared pair of electrons and both the nuclei of the 2 atoms

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3
Q

What is metallic bonding

A

Strong electrostatic forces of attraction between the metal cation and the sea of delocalised electrons

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4
Q

What is electronegativity

A

The ability of an atom to attract a pair of electrons in a covalent bond

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5
Q

What happens when there is a big difference in electronegativities

A

Electrons are transferred from the element of low electronegativity to the element of high electronegativity and the bonding is ionic

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6
Q

What happens when both atoms have medium/high electronegativities and there is a small difference in electronegativities

A

The electron pair is shared fairly evenly between the two elements and the bonding is covalent

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7
Q

What happens when both atoms have a low electronegativity and there is only a small difference in electronegativity values

A

Metallic bonds are formed

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8
Q

What order does the gradual change in type of bonding go between ionic and covalent

A

Ionic bonds
Polarised ions
Polar molecules
Covalent bonds

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9
Q

What are polarised ions

A

Electron clouds in ions become distorted and lop-sided resulting in partial sharing of electrons

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10
Q

What are polar molecules

A

One end of the molecule is slightly more negative compared to the other

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11
Q

What structure do ionic compounds have

A

Giant ionic lattice

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12
Q

What happens when ions lose/gain electrons to have a full outer shell

A

Both elements gain a noble gas electronic structure which confers greater stability

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13
Q

What do co-ordinations mean
E.g: Sodium Chloride has a 6:6 co-ordination

A

Each ion is surrounded by X amount of the other element’s ions
E.g: Each sodium ion is surrounded by 6 chloride ions and each chloride ion is surrounded by 6 sodium ions

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14
Q

Why do ionic compounds have high melting and boiling points

A

Ionic bonds are very strong and it takes a lot of energy to overcome them. This means that ionic compounds are solid at room temperature too

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15
Q

When does the strength of ionic bonds increase

A

As the charge on the ions increase
When the size of the ions decrease

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16
Q

How does ionic size change as you go down the group

A

Increases as there are more electron shells

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17
Q

How does ionic size change as you go across a period

A

Decreases as the proton no. increases, so the force of attraction from the nucleus is greater. Furthermore, this decreases the size of the atom because the electrons are still in the same shell

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18
Q

Why can ionic compounds only conduct electricity when they are molten or dissolved in water

A

Because their ions are free to move and ‘carry charge’

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19
Q

Which kinds of solvents are ionic compounds usually soluble and insoluble in

A

Usually soluble in polar solvents such as water and insoluble in non-polar solvents such as cyclohexene

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20
Q

Why are ionic compounds hard

A

The strength of the bonds between oppositely charged ions is high, therefore a lot of force is required to overcome these bonds

21
Q

Why are ionic compounds brittle

A

The layers of ions slide over each other and ions of the same charge will repel each other and so break the structure with a clean sharp surface

22
Q

What is the name of the orbital formed when a covalent bond forms

A

Molecular orbital

23
Q

What is the general rule about atom size and bond strength

A

The smaller the atom, the stronger the bond

24
Q

What is unique about a dative (co-ordinate) bond

A

Both bonding electrons come from the same atom in the molecule

25
Q

How do dative bonds behave

A

Identically to an ordinary covalent bond

26
Q

How is a dative bond represented

A

By an arrow, pointed away from the atom that contributes both electrons

27
Q

What is the basic shape of a molecule determined by

A

The number of pairs of electrons around the central atom

28
Q

Why might the basic shape of a molecule be distorted

A

The presence of lone pairs of electrons as they create repulsion

29
Q

What shape do 2 pairs of electrons form and what is the bond angle

A

Linear
Bond angle of 180 degrees

30
Q

What shape do 3 pairs of electrons form and what is the bond angle

A

Trigonal planar
Bond angle of 120 degrees

31
Q

What shape do 4 pairs of electrons form and what is the bond angle

A

Tetrahedral
Bond angle of 109.5 degrees

32
Q

What shape do 5 pairs of electrons form and what is the bond angle

A

Trigonal bipyramidal

Bond angle between axial and equatorial atom is 90 degrees

Bond angle between 2 equatorial atoms is 120 degrees

33
Q

What shape do 6 pairs of electrons form and what is the bond angle

A

Octohedral
Bond angle of 90 degrees

34
Q

By how many degrees does a lone pair reduce the bond angle

A

2.5 degrees

35
Q

Why are molecular shapes the way they are

A

The molecule adopts the position that minimises repulsive forces

36
Q

What symbol is used to indicate electronegative charge

A

Delta

37
Q

What do molecules that have one end of the molecule slightly more negative compared to the other have

A

Permanent dipole or a dipole moment

38
Q

How can molecules have polar bonds but be a non-polar molecule

A

If the molecule is symmetrical and the dipoles and pointing towards each other, they can cancel out

39
Q

What happens to polar molecules in an electrical field

A

Deflected

40
Q

What are molecules that contain atoms of similar electronegativities called

A

Non-polar

41
Q

Properties of simple molecular forces

A

Low melting point
Poor electrical conductivity

42
Q

Summary of diamond’s properties

A

Each C bonds to 4 other Cs

Tetrahedral

Very hard

Doesn’t conduct electricity as there are no delocalised electrons

High melting and boiling points due to strong covalent bonds
Mpt - 3550
Bpt - 4830

43
Q

Summary of graphite’s properties

A

Each C bonds to 3 other Cs

Giant covalent structure with hexagonal arrangement of carbon

Weak intermolecular forces between layers

Soft as layers can slide over each other

Can conduct electricity as there are delocalised electrons between layers

High melting and boiling points as strong covalent bonds
Mpt - 3602
Bpt - 4200

44
Q

What happens in metallic bonding

A

Metal atoms lose their outer shell electrons and form a giant metallic lattice of regularly arranged metal ions

The outer electrons contribute to a pool of delocalised electrons

The metallic bond is the electrostatic force of attraction between the metal ion and the delocalised electrons

45
Q

What does the strength of metallic bonding change with

A

Charge on the ion

Size of the ion

Number of delocalised electrons per ion

46
Q

What are the physical properties of metals

A

Ductile and malleable
Good conductors of electricity
High melting points

47
Q

What is enthalpy of fusion

A

The energy required to change 1 mole of a substance from a solid into a liquid

48
Q

What is enthalpy of vaporisation

A

The energy required to change 1 mole of a substance from a liquid into a gas

49
Q
A

Chemistry AQA A-Level (4 decks)

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