C1: periodic table 1

Question 1

down the same group (vertical), elements have?

Answer 1

• same no. of valence electrons
• increasing no. of electron shells

Question 2

across the same period (horizontal), elements have?

Answer 2

• same no. of occupied electron shells
• increasing proton (atomic) no.
• increasing no. of valence electrons

Question 3

atomic radius increases down the group

Answer 3

• although no. of protons in nucleus increases, e are further & shielded by more e shells
• valence e are attracted less strongly to nucleus = not held so tightly

Question 4

atomic radius decreases across the period

Answer 4

• nuclear charge becomes more +ve as no. of protons inc
• although no. of e also inc, outermost e are in same e shell, hence experience relatively similar shielding effect
• outermost e are attracted more strongly to nucleus

Question 5

ionic radius __ down the group, __ across the period
ions with same no. of e called __ ie. Li+, Be2+, B3+

Answer 5

inc, dec
isoelectronic

Question 6

cation is __ than their neutral atom, while anion is __

Answer 6

smaller, bigger

Question 7

why atomic radius of S < Al?

Answer 7

(S and Al are found in the same period)
S has more protons and electrons than Al
-> outermost electrons are in the same shell with relative similar shielding effect
-> higher number of protons attracts the outermost electrons more strongly to the nucleus, reducing the atomic radius.

Question 8

why ionic radius of S2- > Al3+?

Answer 8

(S and Al are found in the same period) S2- has 2 electrons added in the outermost shell to form anion -> it has 3 electron shells -> Al3+ has 3 electrons removed from the outermost shell to form cation, leaving it with 2 electron shells -> S2- has one more electron shell than Al3+

Question 9

across the period, 1st ionization energy __

Answer 9

inc
harder to remove e
…
atomic radius smaller -> outermost e attracted more strongly -> higher energy required

Question 10

down the group, 1st ionization energy __

Answer 10

dec
easier to remove e
…
outermost e further from nucleus -> inc in shielding effect -> weaker attraction to nucleus -> less energy required to remove

Question 11

electronegativity __ down the group, __ across the period

Answer 11

dec, inc

Question 12

S or Cl has a larger 1st ionisation energy

Answer 12

(S and Cl are found in the same period)
Cl
higher nuclear charge than S which attracts the outermost electrons more strongly to the nucleus = harder to remove

Question 13

Mg or Ca has a lower electronegativity value

Answer 13

(Mg and Ca are found in the same group) Ca
bonding electrons further away from the nucleus = dec attraction for bonding e

Question 14

grp2 metals = reducing agents (form cations)

Answer 14

Ba highest tendency to be oxidised = strongest reducing agent
Be = weakest reducing agent

Question 15

grp2 elements:
react with O2 to form __
react with halogens to form __

Answer 15

metal oxides
2Mg(s) + O2 (g) -> 2MgO (s)
metal halides
Mg (s) + Cl2 (g) -> MgCl2 (s)

Question 16

grp 2 elements:
burns in steam to produce __
react with warm water to produce __

Answer 16

Mg (s) + H2O (g) -> MgO (s) + H2 (g)
Mg (s) + 2H2O (l) -> Mg(OH)2 (s) + H2 (g)

Question 17

grp2 rxn with cold water to form __

Answer 17

Other Group 2 elements (except Be and Mg) react with cold water to form metal hydroxides and hydrogen gas
Ca (s) + 2H2O (l) -> Ca(OH)2 (aq) + H2 (g)

Question 18

grp2 hydroxides become more __ down the grp

Answer 18

soluble
Mg(OH)2 is classified as insoluble in water and Ca(OH)2 is considered reasonably soluble in water

Question 19

grp2 decomposition:
carbonates are __ thermally stable down the grp

Answer 19

more
MgCO3 (s) -> MgO (s) + CO2 (g)

Question 20

grp2 decomposition:
metal ions are __ down the grp but has the same charge

Answer 20

bigger
charge density is reduced down the grp
- metal cation is able to polarize carbonate anion

Question 21

identify grp2 elements rxn with H2O
X: colourless solution formed
Y: no rxn
Z: solution with white precipitate

Answer 21

Ca = reacts with water to form Ca(OH)2 which dissolves in water

Be = does not react with water

Mg = reacts with warm water to form Mg(OH)2 which is insoluble in water and appears as a white precipitate

Question 22

Ca(NO3)2 has a higher or lower decomposition temperature than Mg(NO3)2

Answer 22

higher
Ca has a lower charge density and weaker polarising power = nitrate ion is less polarised = more thermally stable

Question 23

down the grp:
grp2 elements __ reactive
grp17 elements __ reactive

Answer 23

more, less

Question 24

down grp17, MPBP __

Answer 24

inc
(non-polar molecules)
molecules become larger = more e move around to set up temporary dipoles = stronger van der Waals forces = intermolecular forces get stronger = more energy required to break forces

Question 25

grp17 elements are oxidising agents (form anions)

Answer 25

F = highest tendency to be reduced = strongest oxidising agent
I = weakest oxidising agent

Question 26

what rxn does grp17 has

Answer 26

displacement

Question 27

grp17 halogens react with H2 to form

Answer 27

H halides
F2 (g) + H2 (g) -> 2HF (g)

Question 28

grp17 rx with water (not important)

Answer 28

2F2 (g) + 2H2O (l) → 4HF (aq) + O2 (g)
Cl2 (g) + H2O (l) → HCl (aq) + HOCl (aq)

Question 29

grp17 rx with AgNO3 & NH3 (not important)

Answer 29

F - no rxn

Question 30

grp17 halides are __ thermally stable down the grp

Answer 30

less
atoms bigger, bond length longer = bonding pair of e further from nucleus = weaker bond = less heat energy required to break