Topic 1 -Atomic structure and periodic table

Question 1

Why does ionisation energy decrease from P to S?

Answer 1

Electrons are paired for the first time Sulfur,the repulsion between the two electrons reduces the IE causing a lower amount of energy needed to break the outer electron

Question 2

what is the tend in IE across a group and why?

Answer 2

Increases across group due to decrease in atomic radius and increase in nuclear charge

Question 3

Trend in IE down a group?

Answer 3

Decreases down a group due to increase atomic radius and decrease in nuclear charge between nucleus and electrons

Question 4

What are giant covalent molecules and what properties do they have ?

Answer 4

Graphite, diamond and silicon dioxide
Solid at room temp
Cannot conduct electricity except for graphite-delocalised electron
Cannot conduct electricity as a liquid
not soluble
High melting point - strong covalent bonds

Question 5

Example of simple molecular and their features

Answer 5

I2,H2O
liquid or gas at room temp
cannot conduct electricity in any form
solubility depends on polarity 
Low melting points- weak forces

Question 6

Examples of Giant ionic substances

Answer 6

Nacl
Solid at room temp
cannot conduct electricity as solid
can conduct electricity as liquid - free electrons
soluble in water
High melting points- strong electrostatic forces

Question 7

Examples of metallic structures and their properties

Answer 7

Mg,Na
solid at room temp
can conduct electricity as solid
can conduct electricity as liquid 
not soluble in water
high melting points- strong electrostatic forces

Question 8

Why does the melting point form Li to Be increase?

Answer 8

their melting points increase due to greater positive charge ions
li+1 be+2

Question 9

Why does the melting point increase for Boron and Carbon

Answer 9

they have very strong covalent bonds that require high amount of energy to break apart

Question 10

Why does melting point decrease for N ,O, F

Answer 10

They are simple covalent molecules held together by weak london forces

Question 11

Why does melting point increase for silicon ?

Answer 11

It is macromolecular therefore have very strong covalent bonds and requires high amount of energy to overcome the forces

Question 12

Why does melting point decrease for Phosphorus , sulfur and chlorine?

Answer 12

They are simple covalent molecules therefore have weak van der waal forces and don’t require high amount of energy

Question 13

Why does argon have the lowest melting temperature?

Answer 13

Has full outer shell therefore is very stable and forms very weak van der waal forces

Question 14

Why are boron and oxygen in period 2 and aluminium and sulfur in period 3 exceptions for the increase in IE ?

Answer 14

Due to quantum behaviour of electrons
Aluminium = in a new orbital further away from nucleus , requires less energy
Sulfur=Electrons are paired for the first time in p orbital , require less energy due to electron repulsion
period 2 follows same trend

Answer 15

silicon has strong covalent bonds that need high amounts of energy whereas sulfur has weak forces van der Waals’ forces

Question 16

why does silicon have a high melting point than sulfur ?

Answer 16

silicon has strong covalent bonds that need high amounts of energy whereas sulfur has weak forces van der Waals’ forces

Question 17

Why does the melting temp increase from sodium to aluminium?

Answer 17

charge increases , more electrons being removed resulting in stronger nuclear charge