Period 3 Flashcards
Why is Na more reactive than Mg?
It takes less energy to lose one e- than to lose two
Generic equation for period 3 metal + water
Metal + water —-> metal hydroxide + Hydrogen
Observations for Na + water
Product
Exothermic
Gas produced
Colourless
Very alkaline solution
Equation for Mg+ cold water
Observation and products
Mg+ 2H2O—-> Mg(OH)2 + H2
Minor bubbles
Sparingly soluble: weakly alkaline
Equation for Reaction of Mg and steam
Mg(g) + H2O(g) —> MgO(s) + H2(g)
Observation of mg and steam
White flame and white solid (fast reaction)
Basic solid
Equation and observations for Na and Oxygen
2Na + 1/2 O2 —-> Na2O
Yellow flame and yellow solid (reacts readily in air)
Equation and observations for Mg and Oxygen
Mg + 1/2 O2 —-> MgO
White flame
White solid (reacts readily in air)
Equation and observations for Al and Oxygen
Rate?
2Al + 3/2 O2 —-> Al2O3
Reacts slowly
Equation and observations for Phosphorus and Oxygen
Observations
P4 + 5O2 —-> P4O10
White smoke
White flame
Why is P4 kept in oil?
How else can it be stored?
P4 ignites spontaneously in air
Under water
Equation and observations for S and Oxygen
S+O2 —-> SO2
Blue flame
Choking gas
Reacts readily in air
Structure and bonding of Na2O and MgO
Acidic?
Giant ionic lattice
Ionic
Basic
Define ionic bonding
Strong electrostatic attraction between oppositely charged ions
Structure and bonding of Al2O3
Giant ionic lattice
Ionic with covalent character
What is the acidity of Al2O3
Amphoteric but does not dissolve in water
Structure and bonding of SiO2
Is it acidic?
Macromolecular
Covalent bonds
Acidic but does not dissolve in water
Structure and bonding of P4O10
Is it acidic or basic?
Simple molecular
Weak VdW forces between molecules
Acidic
Structure and bonding of SO2
Is it acidic or basic?
Simple molecular
Weak van der Waals’ forces between molecules
Acidic
Structure and bonding of SO3
Is it acidic or basic?
Simple molecular
Weak Van der Waals’ forces between the molecules
Acidic
Are ionic oxides acidic?
No they are basic - they contain oxide ions (O2-) which form OH- ions when dissolved in water
Give examples of ionic oxides
Na2O, MgO
What is the acidity of Al2O3?
Amphoteric
Which period three oxides are acidic?
Macromolecular oxides
Simple molecular oxides
Why are ionic oxides basic?
They contain O2- which forms OH- ions in water
Equation for Na2O + water and give the acidity of the product
Na2O + H2O —-> 2NaOH
Very alkaline
Equation for MgO + water and give the acidity of the product
MgO + H2O—-> Mg(OH)2
Alkaline but product is very sparingly soluble
Equation for Al2O3 + water and give the acidity of the product
Al2O3 is insoluble therefore no reaction with water
Al2O3 forms a protective layer on the surface of Al
Acidity: N/A
Equation for SiO2 + water and give the acidity of the product
SiO2 is insoluble (no reaction with water)
N/A
Equation for P4O10 + water and give the acidity of the product
P4O10 + 6H2O —-> 4H3PO4
Acidic as phosphoric acid is formed
Give the structure of phosphoric acid
OH | O=P - OH | OH
What does phosphoric acid dissociate to?
O- | O=P — O- + 3H+ | O-
Equation for SO2 + water and give the acidity of the product
SO2 + H2O —-> H2SO3
Structure of sulphuric (IV) acid
OH | O=S: | OH
Equation for SO3 + water and give the acidity of the product
SO3 + H2O —-> H2SO4
Structure of sulphuric (VI) acid
Give the formula
O || HO-S - OH || O
H2SO4
What is the formula of sulphuric (IV) acid?
H2SO3
Acid + base —->
Salt + water
Rate of Na2O + acid
Exothermic or endothermic?
Fast
Exothermic
Rate of MgO + acid
Slow
Reaction of Al2O3 with HCl
Al2O3 + 6HCl ——> 2AlCl3 + 3H2O
Reaction of Al2O3 with NaOH
Al2O3 + 2NaOH + 3H2O —> 2NaAl(OH)4
When Al2O3 acts as an acid what does the salt contain?
The Al(OH)4 - ion
When SiO2 reacts with bases what does the salt contain?
SiO3 2-
When P4O10 reacts with bases what does the salt contain?
PO4 3-
When SO2 reacts with bases what does the salt contain?
SO3 2-
When SO3 reacts with bases what does the salt contain?
SO4 2-
General equation for neutralisation in the absence of water
Acid + base —-> salt
6Na2O + P4O10 —->
4Na3PO4
What can P4O10 be written as when it is dissolved in water
H3PO4 (phosphoric acid)
What can P4O10 be written as when added to an aqueous base
H3PO4
What can SO2 be written as when added to an aqueous base
H2SO3
What can SO3 be written as when added to an aqueous base
H2SO4
What can SO2 be written as when it is dissolved in water
H2SO3
What can SO3 be written as when it is dissolved in water
H2SO4
How to convert an equation into an ionic equation
Split up aqueous ionic compounds (including acids) into separate ions
Cancel out spectator ions (appear on both sides)
Write final equation
Products of SiO2 and NaOH
Na2SiO3 and water