PERIODICITY

Question 1

define classification

Answer 1

an element is classified as sap,d or f block according to its position in the periodic table which is determined by the proton number

Question 2

define periodicity

Answer 2

repeating pattern of chemical properties going across a period

Question 3

at what ph does sodium have a fast reaction with water in

Answer 3

12-14

Question 4

at what ph does magnesium have a slow reaction with water in

Answer 4

9-10

Question 5

why is magnesium less reactive than water

Answer 5

it has a smaller atomic radius and higher charge compared with sodium, this has a greater electrostatic attraction holding the magnesium lattice together so the reaction has a higher activation energy

Question 6

what colour flame does sodium burn

Answer 6

yellow

Question 7

what colour flame does magnesium burn

Answer 7

white

Question 8

what colour flame does aluminium burn

Answer 8

slow process unless powdered- white powder

Question 9

what colour does red phosphorus burn

Answer 9

red- must be heated prior to reaction

Question 10

what colour does white phosphorous burn

Answer 10

react spontaneously to produce a white smoke

Question 11

define allotropes

Answer 11

physical forms of the same electrons

Question 12

how are the species able to react with oxygen

Answer 12

the species can react in this way because they are purely ionic and so hydration can occur due to the strong covalent character, when non metal oxides react with water, acidic collusions form

Question 13

trends in atomic radius

Answer 13

atomic radius of period 3 elements decrease going from left to right across a period, this is because the increased proton number creates a positive charge attraction for the electrons which are in the same shell with similar shielding

Question 14

trends in metallic bonding

Answer 14

They all contain metallic bonding because this is the strongest bonding and will get even stronger as more electrons are released to the sea of delocalised electrons. the successive ions are smaller and contain more protons so have a strong electrostatic force of attraction between positive metal ions and delocalised electrons so need more energy to break

Question 15

trends in first ionisation energy

Answer 15

increases due to the number of protons increasing and electrons being added to the same shell, there is a small drop between magnesium and aluminium, magnesium has an outer electron in 3s sub shell, aluminium outer electron is slightly easier to remove because the 3p electron is higher in energy. there is also a small drop between phosphorus and sulphur, sulphur has outer electron that is paired up with another electron present in the 3p orbital when the second electron is added to the orbital there is a slight repulsion between 2 negatively charged electrons making it easier to remove