Period 3 Elements Flashcards
What is the equation and observation for the reaction between sodium and cold water
It fizzes around on surface
2Na (s) + 2 H2O (l) → 2 NaOH (aq) + H2(g)
What is the equation for the reaction between magnesium and cold water
Mg(s) + H2O(l) → Mg(OH)2 + H2(g)
This is a very slow reaction
What is the observation and equation for the reaction between magnesium and steam
Mg (s) + H2O (g) → MgO (s) + H2 (g)
Reacts faster than it does with cold water
Reaction and observation for the reaction between sodium and oxygen
4Na (s) + O2 (g) → 2Na2O (s)
Sodium burns with a yellow flame to produce a white solid
Reaction and observation for the reaction between magnesium and oxygen
2Mg (s) + O2 (g) → 2MgO (s)
Burns with a white flame to give a white solid smoke
Reaction and observation for the reaction between aluminium and oxygen
4Al (s) + 3O2 (g) → 2Al2O3 (s)
Burns with a white flame to give a white solid smoke
Reaction and observation for the reaction between silicon and oxygen
Si (s) + O2 (g)→ SiO2 (s)
Burns with a white flame to give a white solid smoke
Reaction and observation for the reaction between phosphorous and oxygen
4P (s) + 5O2 (g) → P4O10 (s)
Burns with a white flame to give a white solid smoke
Reaction and observation for the reaction between sulfur and oxygen
S (s) + O2 (g) → SO2 (g)
Burns with a blue flame to form an acidic choking gas
How is sodium stored and why
Under oil to stop it from coming into contact and reacting with air
How is phosphorous stored and why
Under water to stop it from coming into contact and reacting with air
Describe the structure and bonding in sodium/magnesium/aluminium oxide
The metal oxides are ionic. They have have a giant ionic lattice with strong electrostatic forces of attraction between the oppositely charged ions. They have high MP’s
Explain why the melting point of the oxides increases from Na to Al
The increased charge on the cation makes the ionic forces stronger (bigger lattice enthalpies of dissociation) so increased MP.
Explain the boiling point of SiO2 with reference to its structure and bonding
SiO2 is macromolecular. It has a giant covalent lattice with many strong covalent bonds between atoms. High amounts of energy is needed to break the many strong covalent bonds. It has a very high BP
Describe the structure of phosphorous and sulfur oxides
They are simple molecular with weak Van der Waals and permanent dipole forces between their molecules so have lower BP’s.
Why does Phosphorous oxide have a higher melting poiunt than sulphur dioxide
Phospohorous oxide is a bigger molecules and has more electrons so will have stronger Van der Waals forces between its molecules
How can you prove a compound is ionic
Melt the solid and test its electric conductivity. It will conduct electricity
Why is aluminium metal protected from corrosion in moist air
It is protected by a thin layer of aluminium oxide. The high lattice strength of aluminium oxide and its insolubility in water make the layer impermeable to air and water
What happens to the covalent character of period 3 oxides across the period
Covalent character increases
What happens to the ionic character of period 3 oxides across the period
Decreases
How do metal ionic oxides react with water
They form hydroxides which are alkaline
Why are ionic oxides basic
The oxide ions accept protons to become hydroxide ions in the reaction
Reaction between Na2O and water and the pH of the products
Na2O (s) + H2O (l) → 2NaOH (aq)
pH 14
Reaction between MgO and water and its pH
MgO (s) + H2O (l) → Mg(OH)2 (aq)
pH 10
