periodic table Flashcards
s block
group 1 and 2
- metals that form basic oxides
-reducing agents (donate electrons to easily become cations)
-MPT decreases down the group
p block
-Non metals
- form acidic oxides
-oxidising agent (easily takes electrons to become anions)
-MPT increases down the group
d block
Transition metals
oxidation
oxidation number in increased
(e.g Na (0) become Na (+1))
an oxidising AGENT accepts electrons (therefore being reduced itself)
reduction
oxidation number goes down
(e.g. Br (0) become Br (-1))
A reducing agent DONATES electrons (therefore being oxidised)
redox reaction
both oxidation and reduction occur in the same reaction
- both an oxidising and a reducing agent are present
oxidation number rules
Group 1= +1
Group 2= +2
Group 6= -2
Group 7= -1
Oxygen= -2 (excluding peroxides or with fluorine)
Hydrogen= +1 (excluding hydrides)
oxides
s blocks form oxides when they come into contact with oxygen
4M+O2 –> 2M2O (G1)
2M+O2 –> 2MO
oxides with acid
oxides react with acid to form salt and water
e.g. 2Li2O + 2HCl —> LiCl2 + H2O
S block with water
Will generally form a hydroxide and hydrogen
GROUP 1- reaction’s more intense as you go down the group
2M + 2H2O —> 2MOH + H2
Group 2 with water
Berylium- no reaction
Magnesium- forms an oxide as magnesium hydroxide decomposes at high temps
REST-
M + 2H2O –> M(OH)2 +H2
SOLUBILITY (Mg)
ONLY MgSO4 is soluble (magnesium sulfate)
rest form white precipiate
SOLUBILITY (Ca)
CaSO4 is soluble
CaOH is sparingly soluble
CaCO3 forms white precipitate
SOLUBILITY (Sr)
(all carbonates are insoluble except G1)
SrOH is soluble
SrSO4 is sparingly soluble
(SSS)
Reactivity (G1 and 2)
-elements get more reactive as you go down
-electrons need to be lost
-nuclear pull is weaker so electrons are more easily lost as atoms get larger
-G1 reacts more vigorously as they only have one electron to lose
thermal decomposition
caco3 –> cao + co2
thermal decomposition occurs SLOWER down a group as the element are more THERMALLY STABLE
(occurs in carbonates to form an oxide and carbon dioxide)
(also occurs in hydroxides except water is formed instead of CO2)
solubility in groups
solubility of HYDROXIDES increases down a group
solubility of SULPHATES decreases down a group
solubility of carbonates (soluble for none)
reactions with acid
G1 and 2 oxides and hydroxides form salt and water
strength of base is measured by how easily the elements will dissociate into ions (G1 is stronger)
First four halogens (G7)
F- pale green
Cl- yellow/green
BROmine- BROwn
I- grey solid, purple gas (MLP)
-volatility (tendency to form gas) decreases down the group
-inter molecular forces get stronger as atom increases in size
-reactivity also decrease (less oxidising power)
-less attraction from larger atoms
Halogen reactions (sodium)
EQUATION: 2Na + X2 —> 2NaX
X is a halogen (diatomic)
OBSERVATION: bright red flame (sodium ignites), white precipitate (all halogens are insoluble)
Halogen reactions (iron)
EQUATION (Iodine)
Iodine is less reactive and can only form iron (ii) iodide
Fe +I2 —> FeI2
EQUATIONS (general)
forms iron(iii) hallide
2Fe + 3X2 –> 2FeX3
OBSERVATION- brown gas
silver nitrate test
white prec- cl (prec dissolves in ammonia)
cream prec- br (slightly dissolves in NH3)
yellow prec- I (doesn’t dissolve in NH3)
uses
cl- kills bacteria in water
F- strengthens tooth enamel
