3. Periodicity

Question 1

which oxides are basic and which are acidic?

Answer 1

Ionic acids are BASIC
covalent oxides are ACIDIC

Question 2

Aluminium oxide is … (what kind of oxide is it)

Answer 2

Ionic with covalent character —> AMPHOTERIC

Question 3

what does the period number correspond with?

Answer 3

the principal quantum number, n
of the highest occupied energy level in the elements

Question 4

which groups are part of the s-block?

Answer 4

group 1 - 2

Question 5

which groups are part of the d-block

Answer 5

transition metal groups area idk

Question 6

which groups are part of the p block

Answer 6

3-8

Question 7

whcih groups are part of the f block

Answer 7

the 2 rows below

Question 8

what determines which block an element is placed in?

Answer 8

which orbital it ends on
eg

1s
2s 2s … (d) … 2p 2p 2p 2p 2p 2p

Question 9

definition of atomic radius

Answer 9

half the distance between the nuclei of neighbouring atoms in the pure element

Question 10

atomic radius calculation

Answer 10

distance between 2 nuclei / 2

Question 11

what atomic radius is for :
- noble gas
- non metal
- metal

Answer 11

• van der waal’s radius
• covalent radius
• metallic radius

Question 12

factors affecting atomic radius 2

Answer 12

• nuclear charge : incr protons, incr electrostatic attraction, pulls electrons towards nucleus
• shielding effect (by inner electrons) : e in inner shells repel valence electrons – incr no. of e in inner shells, incr shielding effect, decr electrostatic attraction, incr dist

Question 13

how does atomic radius change in elements in terms of periods and groups?

Answer 13

• across period: decr
  nuclear charge incr, but shielding effect pretty constant
• down group: incr
  valence electrons enter new energy level, further from nucleus

Question 14

what is the difference in ionic radius of cations and anions

Answer 14

cations – SMALLER than parent
- proton number same but fewer electrons – valence more strongly attracted
anions – LARGER than parent
- add electron – incr in repulsion
- have one more occupied shell than cations

Question 15

anionic radius affected by charge

Answer 15

More negative charge: more elections, repulsion higher = larger

Question 16

in the spot along the period where it hops from cation to anion the ionic radius JUMPS. why?

Answer 16

anions have one more occupied quantum shell of electrons

Question 17

DEFINITION of ionisation energy

Answer 17

first ionisation energy:
minimum energy required in REMOVING one mole of VALENCE electrons from one mole of GASEOUS atoms to form one mole of SINGLY POSITIVELY CHARGED gaseous ion

Question 18

periodic trends in ionisation energy

Answer 18

• incr across period
  effective nuclear charge – incr, shielding same, valence closer to nucleus – incr elecstat attraction
• decr down group
  atomic radii – no. of filled shells incr, atom size incr – incr dist = decr elecstat attraction

Question 19

whats special about first ionisation energy in periods 2 and 3

Answer 19

grp 13 lower FIE than grp 2
grp 16 lower FIE than grp 15
(Examples on notes pg 14)

Question 20

electronegativity definition

Answer 20

relative attraction that an atom has for the shared pair of electrons in a covalent bond

Question 21

what is the Pauling scale

Answer 21

method of calculating electronegativity

Question 22

electronogativeity of elements

Answer 22

most electroneg is Fluorine (4.0)
top right corner of p.table then in all directions decr

Question 23

general periodic trends in electronegativity

Answer 23

• incr across period
  atoms smaller, nuclear charge incr, shielding same, effective nuclear charge incr – elecstat att incr
• decr down group
  atoms larger, incr dist betw bonding e and nuclei – decr elecstat att – decr electroneg

Question 24

definition of electron affinity

Answer 24

first electron affinity is the enthalpy change when 1 mol of gaseous atoms acquires 1 mol of electrons to form 1 mol of singly neg charged gaseous ions

Question 25

first electron affinity is exo/endo? why?

Answer 25

exothermic for most elements
- electron added, elecstat att between photons in nucleus and electron
- energy released when nucleus attracts electron (similar to bond forming)

Question 26

electron affinity down a group

Answer 26

less exothermic
- atomic radius incr
- decr att betw nucleus and added electron (brought to a shell further from nucleus)

Question 27

electron affinity across a period + exceptions

Answer 27

more exothermic (more negative)
- incr effective nuclear charge
- decr atomic radius
- added e more strongly attracted by nucleus

nitrogen (E.A. >0)
- has 3 unpaired e in the 2p sublevel
- incoming e pairs with one in the p-orbital = extra repulsion component
- energy needs to be supplied ti overcoem the inter-e.nic repulsion between the paired

Question 28

second electron affinity definition

Answer 28

when 1 mole of singly negatively charged gaseous ions aquires 1 mol of electrons to form 1 mol of doubly neg charged gaseous ions

Question 29

melting involves….

Answer 29

overcoming the forces of attraction betw ions, atoms or molecules

Question 30

melting depends on… 2

Answer 30

• structure (packing)
• electrostatic forces of attraction betw particles

Question 31

structure of Li, Be, Na, Mg, Al

Answer 31

giant metallic
- metallic bonds between cations and sea of delocalised electrons

Question 32

strcutre of B, C, Si

Answer 32

giant molecular
- covalent bonds throughout the entire giant 3-D network structure

Question 33

across period melting points

Answer 33

rises thru metals and metalloids, drops abruptly for non-metals

Question 34

melting point in Na to Al (metal) 4

Answer 34

• due to giant metallic structure
• MP incr from Na to Al (metallic bond strength incr – decr in metallic radius, incr in no of e donated)
• elecstat att betw cations and delocalised e INCR
• more e req to break

Question 35

melting point in Si (metalloid) 3

Answer 35

• higher than na, mg, al
• due to giant molecular structure / giant 3-D network
• high MP due to e req to overcome many strong covalent bonds (structure)

Question 36

melting point in P to Ar (non metals)

Answer 36

• low melting pt, decr across
• simple molecular strucutre
• attracted by instantaneous dipole - induced dipole forces (less thermal e req to overcome)
• relative molc mass incr = ID-IDF incr
• incr strength of ID-IDF down grp

Question 37

melting points in noble gases

Answer 37

very low
- instantaneous dipole-induced dipole forces are weak
- down grp, m,bp incr bc more e that are easily polarised

Question 38

mp and bp down group 1 (alkali metals)

Answer 38

down grp 1
- mp DECR
- strength of metallic bond DECR
- decr in charge density of cations – elecstat att betw cations and deloc e DECR
- less e req to break the weaker metallic bond

Question 39

mp and bp down grp 17 (halogens)

Answer 39

down grp 17
- mp and bp incr
- incr in electron cloud size – incr polarizability – incr strength of ID-IDF
- more energy req to overcome the incr strength of the forces

Question 40

alkali metals (1) down the grp:
- atomic, ionic rad
- first ionisation e
- electroneg
- reactivity

Answer 40

• INCR atomic and ionic rad
• DECR first ionisation energy
• DECR electroneg
• INCR reactivity
  good reducing agents, low mp, highly reactive

Question 41

reaction of alkali metal with water and halogens (MEMORISE EQNS)

Answer 41

water –> form alkaline solution + H2 gas
2K (s) + H2O (l) –> 2 KOH (aq) + H2

non metals eg halogens –> ionic compounds
Na (s) + Cl2 (g) –> 2NaCl (s)

Question 42

halogens (17) down the grp:
- atomic, ionic rad
- first ionisation e
- electroneg
- reactivity
- oxidising strength

Answer 42

• INCR atomic and ionic radius
• DECR first ionisation energy
• DECR electroneg
• DECR reactivity
• DECR oxidising strength

Question 43

reaction of halogens with alkali metals

Answer 43

Ag+ (aq) + X- (aq) –> AgX

eg
AgCl white, AgBr cream, AgI yellow

Question 44

displacement reactions of cholrine, bromine and iodine

Answer 44

oxidising strength decr down grp
(chlorine strongest)
eg
Cl2 + 2I- –> I2 (brown ppt) + 2Cl-