Topic 2 - Bonding and Structure I

Question 1

Definition of Metallic Bonding

Answer 1

A metallic bond is the electrostatic force of attraction between positive metal ions and the delocalised electrons.

Question 2

Melting Points of Metallic Bonding

Answer 2

Metals have a high melting point due to the strong electrostaic forces between the positive ions and the sea of delocalised electrons. This requires a lot of energy to overcome.

Question 3

Trend in melting points for metallic bonding

Answer 3

Metallic bonding gets stronger because in Mg there are mroe electrons in the outer shell that are being released to the sea of electrons. The Mg ion is also smaller and has one mroe proton. Therefore there is a stronger electrostatic attraction between the positive metal ions and the delocalised electrons and higher energy is needed to break bonds.

Question 4

Conductivity of Metals

Answer 4

All metals conduct electricity when molten and when solid. The sea of delocalised electrons is moblile and moves through the lattice of metal ions.

Question 5

Malleabillity of Metals

Answer 5

Metals are malleable because the positive ions in the lattice are all identical. So therefore the planes of ions can easily slide over eachother.

Question 6

Definition of ionic bonding

Answer 6

An ionic bond is the strong electrostatic force of atraction between oppositely charged ions formed by electron transfer.

Question 7

Conductivity of Ionic

Answer 7

Cannot conduct in solid state as ions are fixed.

Conducts in molten state as ions are free moving.

Question 8

Melting points of ionic solids

Answer 8

Depends on ion-ion forces.

Ions with small radius give stronger forces of attraction.

Question 9

Brittle nature of ionics

Answer 9

Little force allows the ions be next to similar ions, this will add a force of repulsion.

Question 10

Covalent Bond Definition

Answer 10

A covalent bond is strong ans is caused by electrostatic attraction between the bonding shared pair of electrons and the two nuclei.

Question 11

Effect of multi bonds on bond strength and length

Answer 11

Nuclei joined by multiple bonds have a greater electron density. This causes an greater force of attraction between the nuclei and the electrons between them, resulting in a shorter bond length and greater strength.

Question 12

Definition of a dative bond

Answer 12

A dative bond forms when the shared pair of electrons in the covelant bond come from only one of the bonding atoms.

Question 13

Shapes of Molecules

Answer 13

Linear: 2,0, 180
Trigonal Planar: 3, , 120
Tetrahedral: 4,0, 109.5
Trigonal pyramidal: 3,1 107
Bent, 2,2 104.5
Trigonal Bipyramidal 5,0 120 and 90
Octahedral 6,0 90

Question 14

Electronegativety definition

Answer 14

Electronegativity is the relative tendency of an atom in a covalent bond in a molecule to attract electrons in a covalent bond to itself.

Question 15

Factors affecting electronegativity

Answer 15

Across the group, the atomic radius decreases as the number of protons in the atom increases. Therefore the electronegativity increases.

Down the group, the atomic radius increases and the shielding increases, Therefore the electronegativity decreases.

Question 16

How are polar bonds made?

Answer 16

A polar bond forms when the elements in the bond have diffrent electronegativities. It has an unequal distribution of electrons producing a charge seperation.

Question 17

Polar and non polar molecules

Answer 17

Indicidual dipoles on the bonds cancel out due to symmetrical shape of molecule. The molecule is non polar.

Question 18

How are London Forces made?

Answer 18

Electrons in a covalent molecule oscillate within thier atomic orbitals or covalent bonds.
The density can fluctuate and parts may become more negative.
These tempoary diapoles can form diapoles in neighbouring molecules.

Question 19

Factors affecting size of London Force

Answer 19

More electrons mean a higher chance of diapole forming making the London Forces stronger.
The shape of the m,olecule can also have3 an effect on the size of the London forces. Long straight chain alkanes have a larger surface area on contact with the molecules.

Question 20

Hydrogen bonding

Answer 20

Happens between hydrogen atoms and one of the three most electronegative atoms which must have an avalible lone pair of electrons.

Question 21

Ionic substances dissovling in water

Answer 21

Ionic lattice dissovles by breaking up the bonds between metal ions and water molecules.
The negative ions are attracted to the delta positive hydrogen and the positive ions are attacted tot he delta negative oxygen.

Question 22

Solubility of alcohol

Answer 22

Smaller alcohols can form hydrogen bonds in water

The longer the chain the less soluble it becomes.