Thermochemistry and Properties - Helpful sentence structures

Question 1

Atomic Radius

Answer 1

same group but 1 has extra energy level thus further from the nucleus, inner shell shield outer shell from nucleus, making e-e repulsions to the inner shell, with less attraction of the outer shell to the nucleus.

Question 2

Ionic
Na+ and Cl-

Answer 2

Positive. —->
atom and the ion have the same number of proton/nuclear charge but when the sulfur atom gains two electrons to form the sulfur ion, there is increased electron-electron repulsion in the valence energy level. As a result, the electrons move further apart, and therefore the S?- ion has a larger radius than the S atom.

• atom has occupied level and the ion has occupied levels

negative. —–> Sulfur and the sulfur ion have the same number of proton/nuclear charge but when the sulfur atom gains two electrons to form the sulfur ion, there is increased electron-electron repulsion in the valence energy level. As a result, the electrons move further apart, and therefore the S?- ion has a larger radius than the S atom.

• i ncreased e-e repulsion in the valence energy level move further aparent

Question 3

Electronegativity

Answer 3

Across (increases) period
- there would ahve the same amount of shield from the inner energy levels one with more proton will have greater attraction for bonding electron thus higher e

decrease
further down has an extra energy level more shielding and ee repulsion even if it has more protons but valence electron are away from the nuceu thus e decreases

Question 4

Ionisation Energy Across

Answer 4

Across (increase in period)
e being added to the same e levels, no increase in repulsion between e level. the nuclei with more proton = more electrostatic attraction

decrease (down group):
due to more energy level further away from the nculeus more repusion and shielding, e attraction decreasing with distance, easier to remove. increase in proton down the group counteracted by increasing distance between e and n being removed.

Question 5

BP and MP for the strength of bonds

Answer 5

all molecules will have tempoary dipoles, but xxx and xxx will have larger molar mass/electron coloud(gmol) than xxx, therefore will form stronger temp dipoles. however xxx have permant dipoles or hydrogen bonds which are strong which is why xxx have the highest mp/bp compared to xxxx.

Question 6

fusion of v

vap of v

sub of

Answer 6

f = H is the heat change when 1 mole of an substance goes from solid to liquid

vap = H is the heat change when 1 mole of an substance goes from liquid to gas

sub= H is the heat change when 1 mole of an substance goes from solid to gas.

Question 7

fusion definition

Answer 7

enthalpy change whne 1 mole of an substance is formed with all reactants and products in standard state

Question 8

Combusition def

Answer 8

enthalpy change when 1 mole of an substance is burnt with oxygen with all reactants and products in standard state.

Question 9

entropy

Answer 9

Entropy increases –>
1. there are more particles in the products than reactants
2. the products are more disordered eg (gas)

Entropy Decrease
1. there are less particles in the products than reactants
2. the products are less disordered eg (solid)

Entropy increases –> surrounding
Exothermic is heating up (gaining heat energy thus are move faster)

Entropy decreases –> surrounding
Endothermic is cooling down

Question 10

polarity

Answer 10

non - polar
the xx molecule is symetrical as the bond dipoles are evenly distributed to the central atom and will cancel out and does not have a molecular dipole thus is non polar.