2.4 Period 3 Flashcards
What are the types of each element in period 3?
Sodium, magnesium and aluminium = metallic
Silicon = metalloid
Phosphorus, sulfur and chlorine = non-metals
Argon = Nobel gas
Which elements do we need to know that react with water?
Sodium and magnesium
Information about reaction between sodium and water?
Sodium reacts ionically to form a 1+ positive ion
2Na + 2H2O -> 2NaOH + H2
This reaction is vigorous - fizzes rapidly
Less energy is required to ionise sodium (than Mg) therefore sodium is more reactive
Information about reaction between magnesium and water?
Magnesium reacts ionically to form a 2+ positive ion
Mg + 2H2O -> Mg(OH)2 + H2
This reaction is slow
How can we change the speed of the magnesium + water reaction?
By using steam instead of water provides greater energy resulting in a violent reaction
Mg + H2O(g) -> MgO(s) + H2
Magnesium burns with a bright white flame
How do we react period 3 elements with oxygen?
Using a gas jar containing oxygen
The combustion spoon (with the sample) is placed inside the jar after being heated
What are the products of period 3 elements and oxygen?
Na2O MgO Al2O3 SiO2 P4O10 SO2 SO3
Information about sodium and oxygen?
Sodium is stored under oil to stop it reacting with water vapour in the air = need to dab oil off
Burns with a yellow flame
Produces a white powder (shown as a white mist)
Universal indicator solution goes: Purple
pH: 14
Na2O(s) - ionic
Information about magnesium and oxygen?
Magnesium has a reactive oxide layer - scraped off with sandpaper
Burns with a white flame
Produces a white powder (shown as a white mist)
Universal indicator solution goes: Purple
pH: 10
MgO(s) - ionic
Information about aluminium and oxygen?
Aluminium is an explosive grey powder
Burns with a white flame and gives orange sparks
Produces a white powder (shown as a white mist)
Universal indicator solution goes: Green
pH: 7
Al2O3(s) - ionic (with a degree of covalency)
Information about silicon and oxygen?
You have to heat it very strongly for a reaction
pH: 7
SiO2 - macromolecular
Information about phosphorus and oxygen?
Red phosphorus is used (white phosphorus will react in air spontaneously) - allotropes
Burns with a orange flame
Produces a white powder (shown as a white mist)
Universal indicator solution goes: Red
pH: 1
P4O10(s) - covalent
P4O6 - can be formed with a lack of O2
Information about sulfur and oxygen?
Burns with a pale blue flame
Produces a colourless gas
Universal indicator solution goes: Red
SO2 - pH 3
SO3 can also form but requires high temperatures and a catalyst
pH 1
What are the natural formed of phosphorus and sulfur?
P4
S8
What is the bonding of period 3 oxides?
Na2O - ionic MgO - ionic Al2O3 - ionic (degree of covalency) SiO2 - macromolecular covalent P4O10 - covalent SO2 - covalent
What are the melting point trends of period 3 oxides?
Na2O
Increase to MgO
Slight decrease to Al2O3 (not below Na2O)
SiO2, P4O10 and SO3 all decrease from then
Which period 3 oxides react with water?
Na2O -> NaOH
MgO -> Mg(OH)2
P4O10 -> H3PO4 (phosphoric acid)
SO2 -> H2SO3 (sulfurous acid)
SO3 -> H2SO4 (sulfuric acid)
Which period 3 oxides don’t react with water? Why?
Al2O3 and SiO2
They are insoluble in water
What ions are present in the period 3 oxide + water solutions? pH of the solutions?
NaOH -> Na+ + OH- (pH 14)
MgO -> Mg2+ + OH- (pH 10)
H3PO4 -> H+ + H2PO4- (pH 2)
H2SO3 -> H+ + HSO3- (pH 3)
H2SO4 -> H+ + HSO4- (pH 4)
What are some equations for period 3 oxides with an acid?
Na2O + 2HCl -> 2NaCl + H2O
Na2O + H2SO4 -> Na2SO4 + H2O
MgO + 2HCl -> MgCl2 + H2O
MgO + H2SO4 -> MgSO4 + H2O
What are some equations for period 3 oxides with alkaline?
SiO2 + 2NaOH -> Na2SiO3 + H2O
P4O10 + 12NaOH -> 4Na3PO4 + 6H2O
H3PO4 + 3NaOH -> Na3PO4 +3H2O
SO2 + NaOH -> NaHSO3
NaHSO3 + NaOH -> Na2SO3 + H2O
SO3 + NaOH -> NaHSO4
What are some equations with Al2O3 - acid or base?
Al2O3 will react with an acid and a base - amphoteric
Al2O3 + 6HCl -> 2AlCl3 + 3H2O
Al2O3 + 2NaOH + 3H2O -> 2NaAl(OH)4
(Needs Hot, conc NaOH)
It is insoluble in water
