Periodicity

Question 1

What is the first ionisation energy?

Answer 1

= energy required to remove 1 electron from each atom in 1 mole of gaseous atoms -> forms 1 mole of gaseous 1+ ions

Question 2

What 3 factors effect the first ionisation energy?

Answer 2

• atomic radius
• nuclear charge
• electron shielding

Question 3

Why does it require more energy to remove the 2nd electron?

Answer 3

After 1 is lost, the rest is pulled closer to the nucleus (i.e. More attraction) = more ionisation energy required
Change = larger with successive shells (closer to nucleus)

Question 4

How did Mendeleev arrange the periodic table?

Answer 4

Atomic mass, grouped with similar properties + left gaps

Question 5

What can successive ionisation energies predict?

Answer 5

• no of electrons in outer shell
• group of element in periodic table
• identity of an element

Question 6

Giant covalent

Answer 6

• High mp + bp ∵ strong covalent
• insoluble in all solvents ∵ covalent
• non-conductors (except graphene)

Question 7

What is Ca(OH)2 used for?

Answer 7

Increase pH of acidic soil

Question 8

Why do we add cyclohexane to Halides

Answer 8

1) to distinguish between aqueous bromine and iodine

2) they dissolve easier in cyclohexane than water

Question 9

What is Astatine?

Answer 9

Rare halide ∵ v.radioactive