Bonding (Not finished) Flashcards

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
How do dative bonds behave
Identically to an ordinary covalent bond
26
How is a dative bond represented
By an arrow, pointed away from the atom that contributes both electrons
27
What is the basic shape of a molecule determined by
The number of pairs of electrons around the central atom
28
Why might the basic shape of a molecule be distorted
The presence of lone pairs of electrons as they create repulsion
29
What shape do 2 pairs of electrons form and what is the bond angle
Linear Bond angle of 180 degrees
30
What shape do 3 pairs of electrons form and what is the bond angle
Trigonal planar Bond angle of 120 degrees
31
What shape do 4 pairs of electrons form and what is the bond angle
Tetrahedral Bond angle of 109.5 degrees
32
What shape do 5 pairs of electrons form and what is the bond angle
Trigonal bipyramidal Bond angle between axial and equatorial atom is 90 degrees Bond angle between 2 equatorial atoms is 120 degrees
33
What shape do 6 pairs of electrons form and what is the bond angle
Octohedral Bond angle of 90 degrees
34
By how many degrees does a lone pair reduce the bond angle
2.5 degrees
35
Why are molecular shapes the way they are
The molecule adopts the position that minimises repulsive forces
36
What symbol is used to indicate electronegative charge
Delta
37
What do molecules that have one end of the molecule slightly more negative compared to the other have
Permanent dipole or a dipole moment
38
How can molecules have polar bonds but be a non-polar molecule
If the molecule is symmetrical and the dipoles and pointing towards each other, they can cancel out
39
What happens to polar molecules in an electrical field
Deflected
40
What are molecules that contain atoms of similar electronegativities called
Non-polar
41
Properties of simple molecular forces
Low melting point Poor electrical conductivity
42
Summary of diamond's properties
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
Summary of graphite's properties
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
What happens in metallic bonding
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
What does the strength of metallic bonding change with
Charge on the ion Size of the ion Number of delocalised electrons per ion
46
What are the physical properties of metals
Ductile and malleable Good conductors of electricity High melting points
47
What is enthalpy of fusion
The energy required to change 1 mole of a substance from a solid into a liquid
48
What is enthalpy of vaporisation
The energy required to change 1 mole of a substance from a liquid into a gas
49