Periodic table

Question 1

How are elements arranged in the periodic table

Answer 1

Elements are arranged in the order of increasing atomic number

Question 2

what are rows

Answer 2

periods: number of occupied electron shells

Question 3

what are columns

Answer 3

groups: number of outermost shell/ valence electrons

Question 4

properties of group 18/0

Answer 4

they are noble gases and all are colourless gases that are very stable and inert because they have already had either duplet structure or octet structure, giving extra stability to the atoms.

Question 5

chemical properties of transition elements

Answer 5

1. Form compounds with more than one charge
2. Form a variety of complex ions
3. Form coloured compounds
4. Act as catalyst when in either the form of elements or compounds

Question 6

what is region 1 and 2 considered

Answer 6

It is the s block and p block and they are regarded as representative or main group elements.

Question 7

which group are metals and what is the exception

Answer 7

Group 1, group 2 and
group 3 except boron are metals

Question 8

physical properties of group 1,2,3

Answer 8

shiny appearance, malleable, ductile and good electrical and thermal conductivity

When reacted, they tend to lose electron(s) to form cations.

Question 9

what does region 3 consist of

Answer 9

It is the d block and consists of transition elements

Question 10

what does region 4 consist of

Answer 10

It is the f block and consists of lanthanides and actinides, which interrupt periods 6 and 7 on the Periodic
table.

Question 11

properties of group 4 to group 7 elements

Answer 11

● Most of the elements in groups 4 to 7 are non-metals which lack distinctive physical properties that characterize them.

● Most of them are poor conductors of heat and electricity.

● When they react, they tend to gain electron(s) to form anions.

Question 12

properties of metalloids/semi-metals

Answer 12

● They have properties in between those of metals and non-metals.

● Typical metalloids have a metallic appearance, but they are brittle and only fair conductors of electricity.

● Chemically, they mostly behave as non-metals.

e.g. boron and silicon

Question 13

physical properties of transition elements

Answer 13

1. High electrical and thermal conductivity
2. High melting point
3. Malleable
4. Ductile

Question 14

properties of f-block elements

Answer 14

Lanthanides (Z = 58 to 71) are reactive, silver-coloured metals that tarnish when exposed to air.

Actinides (Z = 89 to 103) are similar to typical metals but they are radioactive.

Question 15

properties of group 1 metals

Answer 15

they are alkali metals, The elements in this group are shiny and silvery metals. They are generally soft and can be easily cut with a knife. Since they are very reactive, they should be stored in paraffin oil (a non-aqueous solvent)
to prevent them from contact with air and moisture / water.

Question 16

properties of group 2 metals

Answer 16

They are called alkaline earth metals, they show similar properties (shiny, silvery, soft, cut with knife, paraffin oil, prevent moisture and air) to those in group 1 but less reactive

Denser and harder than group 1 metals

Question 17

why does the reactivity of group 1 and 2 metals increase down the group

Answer 17

Reactivity of group 1 and 2 metals increases down the group, because of
the increasing trend of atomic radius.

Question 18

what is atomic radius

Answer 18

half of the distance between the nuclei of two neighbouring atoms

Question 19

what does atomic radius refer to

Answer 19

It refers to the distance from the nucleus to the outermost shell/valence
electrons of the atom.

Question 20

why does an increasing trend of atomic radius affect the reactivity

Answer 20

● Going down these two groups, the number of occupied electron shells of the atoms increases.

● The electrostatic force of attraction between the nucleus and the outermost shell electrons becomes weaker.

● Less energy required to remove this
outermost shell/valence electron

Question 21

what is the energy required to remove the outermost shell electron called and what is it

Answer 21

This energy is referred as ionisation energy (I.E.), which is the minimum
amount of energy required to remove one mole of electrons from one
mole of gaseous atoms at ground state.

Question 22

equation of ionisation energy

Answer 22

Equation: X (g) → X+ (g) + e-

Question 23

properties of group 17/7

Answer 23

they are called halogens and the elements in this group are all poisonous and reactive non-metals. They have different colour and physical states under ambient conditions

Question 24

colour of fluorine, chlorine, bromine and iodine

Answer 24

fluorine : pale green gas
chlorine : pale green gas
bromine : reddish brown liquid
iodine : black solid

Question 25

reactivity of halogens when going down the group

Answer 25

● Reactivity of these elements decreases down the group

● because the atomic radius of these elements increases.

● The electrostatic attraction between the nucleus and the additional electrons becomes weaker.

In other words, the affinity for an electron decreases.

Question 26

what is electron affinity (E.A)

Answer 26

It is the energy released when one mole of gaseous atoms gains one mole
of electrons.

Question 27

equation of electron affinity

Answer 27

X (g) + e- → X- (g)