periodicity and ionisation energy

Question 1

How are elements in the periodic table arranged? (3)

Answer 1

1. By increasing atomic number
2. Grouped into columns with similar chemical and physical properties due to the same number of outermost electrons
3. Grouped into periods showing repeating trends(periodicity)

Question 2

What is periodicity?

Answer 2

Regular, repeating patterns of atomic, physical, and chemical properties with increasing atomic number

Question 3

What is the first ionisation energy definition?

Answer 3

The energy required to remove one electron from each atom in one mole of a gaseous element to form one mole of gaseous 1+ ions

Question 4

What are the trends in successive ionisation energies? (2)

Answer 4

1. Within each shell it increases as the outermost shell is pulled closer to the nucleus as electrons are removed
2. There are jumps between shells in ionisation energies as the electron is removed from a lower energy shell, requiring more energy

Question 5

What are the three factors affecting ionisation energies?

Answer 5

1. Shielding
2. Charge
3. Atomic radius

Question 6

How does electron shielding affect ionisation energy?

Answer 6

the lower the number of shells = the lower the electron shielding(repulsion from a full shell of electrons to electrons in non-full shells)
less shielding = greater nuclear attraction
greater nuclear attraction = more energy required to remove electrons therefore higher ionisation energy

Question 7

How does nuclear charge affect ionisation energy?

Answer 7

greater atomic number = greater the nuclear charge(attraction between electrons and positive nucleus)
greater nuclear charge = greater nuclear attraction
greater nuclear attraction = more energy required to remove electrons therefore higher ionisation energy

Question 8

How does atomic radius affect ionisation energy?

Answer 8

greater number of shells = smaller nuclear charge = greater atomic radius
small atomic radius = greater nuclear attraction
greater nuclear attraction = more energy required to remove electrons therefore higher ionisation energy

Question 9

periodic trends, shielding, nuclear charge, atomic radius

Answer 9

shielding - same across periods and increases down groups because of new energy levels
nuclear charge - increases across periods and down groups because of new energy levels
atomic radius - decreases across periods as nuclear charge increases so electrons are closer

Question 10

ionisation energy

Answer 10

increases across periods - S C AR
decreases down groups - S C AR

Question 11

what are the two anomalies for periodicity

Answer 11

group 2-3 : ionisation energy decreases as electrons are being removed from the p subshell rather than the s subshell, p has higher energy and so experiences less nuclear attraction since it is further away
group 5-6: ionisation energy decreases as electrons start to pair up in their orbitals, the repulsion between electrons decreases the energy required to remove the outer electron

Question 12

Why does the melting point increase from group 1 to 4 and then decrease from group 4 to 5?

Answer 12

1 - 4 : elements have giant structures, bonded through metallic bonding rather than covalent
4 -5 : elements have simple molecular structures, bonded through weak intermolecular forces, requiring less energy to overcome