(1) Period 3 Flashcards
Outline the trend in Atomic Radius across Period 3.
DECREASES
- Increase in Nuclear Charge
- Same amount of Shielding
- Increased attraction between positive nucleus and outer electrons
Outline the trend in Electronegativity across Period3.
INCREASES
- Increase in Nuclear Charge
- Same amount of Shielding
- Electrons are increasingly able to withdraw electron density from a covalent bond
Outline the general trend in First Ionisation Energy across Period 3.
INCREASES
- Increase in Nuclear Charge
- Same amount of Shielding
- Electrons are held increasingly tight to positive nucleus so require more energy to remove
Outline and Explain the 2 deviations from the general trend in First Ionisation Energy across Period 3.
Al has a lower 1st IE than Mg because:
- Mg has a 3s electron removed
- Al has a 3p electron removed
- 3p is higher in energy than 3s
S has a lowest 1st IE than P because:
- P has a 3p electron removed which is unpaired
- S has a 3p electron removed which is paired
- Paired electrons repel
Which does Melting Point increase from Na to Al?
- Charge on the metal ion increases (Na+, Mg2+, Al3+)
- Size of metal ion decreases across period
- Increase in strength of attraction between the metal ions and delocalised electrons
Why does Silicon have the highest MP?
- Macromolecular structure
- Many covalent bonds
- Which are very strong
Why does MP decrease from P4 to Ar?
- P4, S8, Cl2 and Ar all have a simple molecular with Van der Waal’s between molecules
- Strength of VdW’s depends on molecule’s size
- S8 is largest, then P4, then Cl2, then Ar.
- Ar exists as single atoms so has the weakest VdW’s between atoms.
Why does Al have the highest Boiling Point?
In the liquid state, Al still has strong electrostatic attractions between ions and delocalised electrons so still requires a large amount of energy to boil (whereas once Si has melted most of its strong covalent bonds have been broken so it requires only a little extra energy to boil).
Which of the Period 3 Oxides are Basic?
Na2O and MgO.
Which of the Period 3 Oxides are Acidic?
SiO2, P4O10 and SO2/SO3
Define Amphoteric.
Acidic or Basic.
Which of the Period 3 Oxides are Amphoteric?
Al2O3.
Which Period 3 Oxides are White Solids?
Na2O3, MgO, Al2O3 and SiO2.
Why do Na2O and MgO form an Alkaline Solution with Water?
-They contain O2- ions
-Which react with water
To form OH- ions
How does Al2O3 react with HCl?
Al2O3(s) + 6HCl(aq) –> 2AlCl3(aq) + 3H2O(I)
How does Al2O3 react with NaOH?
Al2O3(s) + NaOH(aq) + 3H2O(I) –> 2NaAl(OH)4(aq)
Explain, using an equation, why Silicon Oxide is classified as an Acidic Oxide?
SiO2 neutralises bases.
SiO2 + 2NaOH –> Na2SiO3 + H2O
Write an Ionic Equation for the reaction between Phosphorus Oxide and excess of Sodium Hydroxide.
P4O10 + 12OH- –> 4PO43- + 6H2O
Which Period 3 Oxides are insoluble in Water?
Al2O3 and SiO2. When they are added to water, the pH is 7.
How does Sodium react with Water? What pH is the solution formed?
2Na(s) + 2H2O(I) –> 2NaOH(aq) + H2(g)
pH = 13/14
How does Magnesium react with Water? What pH is the solution formed?
Mg(s) + H2O(I) –> Mg(OH)2(aq) + H2(g)
pH = 9/10
How does Magnesium react with Steam?
Mg(s) + H2O(g) –> MgO(s) + H2(g)
How does Chlorine react with Water? What pH is the solution formed?
Cl2(g) + H2O(I) HClO(aq) + HCl(aq)
pH = 2/3
How does Chlorine react with Water in the presence of sunlight? What pH is the solution formed?
2Cl2(g) + 2H2O(I) –> 4HCl(aq) + O2(g)
pH = 2/3
