OCR AS Chemistry (F321.3) - The Periodic Table Revision Notes

These revision notes are for The Periodic Table - the third module of F321 (Atoms, bonds and groups) from OCR AS Chemistry A.

These notes are compatible with Microsoft Word 2007 onwards.

Hope they helped!

HideShow resource information

Pages in this set

Page 1

Preview of page 1
OCR AS Chemistry Notes


GROUP 2 ELEMENTS AND THEIR COMPOUNDS
Have their outermost electron placed on s subshell
Readily react to lose 2 electrons
o M M 2+ + 2e-

Trends down the group:

1st ionisation energy decreases
o Distance between outermost electron and nucleus increases
o More shielding
o…

Page 2

Preview of page 2
Mg acted as reducing agent, donating its electrons and oxidising itself


OXIDATION NUMBERS
Many covalent substances participate in redox reactions where there is no electron transfer
o 2H 2 + O2 2H 2O Both covalent reactions, no electron transfer and yet redox
o C + O2 CO2
In order to…

Page 3

Preview of page 3
REACTIONS OF GROUP 2 ELEMENTS (AND THEIR COMPOUNDS)
1. REACTION WITH WATER
Reactivity down the group increases

Does not react with cold water
Be Reacts only with steam when red hot

Reaction with cold water is extremely slow

M g (s) + 2H 2O (l) Mg(OH )2 (aq) + H…

Page 4

Preview of page 4
Sr Red

Ba Green

Most oxides are only very slightly soluble in water
o When they do dissolve, they form weakly alkaline solutions



3. REACTION OF GROUP II METAL OXIDES WITH WATER
M gO (s) + H 2O (l)Mg(OH )2 (s) does not dissolve
C aO (s) + H 2O…

Page 5

Preview of page 5
Attraction for cation is a lot higher



All group 2 carbonates decompose in Bunsen flame
However they require different amounts of energy to decompose
o It requires more and more energy to decompose carbonates as you go down group 2
BeCO3 decomposes at room temperature
BaCO3 requires most energy to…

Page 6

Preview of page 6
PHSICAL PROPERTIES
All exist as diatomic molecules
All are coloured

F2 Pale yellow

Cl2 Green

Br2 Red-brown

I2 Black-purple



At R.T.P:

F2 Gases

Cl2

Br2 Liquid

I2 Solid




All dissolve in water, but only very slightly
o Because atoms have same electronegativity, molecules are non-polar
Can only form Van der…

Page 7

Preview of page 7
3. OXIDISING ABILITY DECREASES:
o More shells
More shielding
Further from nucleus
Electrons less easily attracted
o This overcomes increasing nuclear charge



4. They all exhibit variable oxidation numbers

Cl2O7 / +7
NaClO4
ClO3 +6
NaClO3 +5
ClO2 +4
KClO2 +3
Cl2O / NaClO +1
Cl2 0
NaCl -1
o…

Page 8

Preview of page 8
H 2 (g) + Br2 (l)2HBr (g)



3. HALOGENS ACTING AS OXIDISING AGENTS:
o Displacement reactions

F2 Most powerful oxidising agent (most reactive)

Cl2

Br2

I2 Least powerful (least reactive)



o The more powerful oxidising agent will always get reduced




0 Cl2 + - 1 2K I - 1 2K…

Page 9

Preview of page 9
3NaClO 2NaCl + N aClO3



REACTIONS OF HALIDE IONS:
o All halides are soluble
EXCEPT: Lead halides and AgCl / AgBr / AgI
o Precipitates form when solution of halide ions is treated with either Ag+ or Pb2+

N aCl (aq) + AgNO3 (aq)AgCl (s) + NaNO3(aq)

Cl-(aq) + Ag+(aq)AgCl…

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all resources »