2.4 Period 3 Flashcards
(14 cards)
Describe trend of an electronegativity across a period
- increases
- nuclear charge increases
- same shielding
Equation for when sodium and cold water react together
2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g
Equation for when magnesium and cold water react together
Mg(s) + 2H2O(l) -> Mg(OH)2(aq) + H2(g)
Equation for when magnesium and steam react together
Mg(s) + H2O(g) -> MgO(s) + H2(g)
Equation for when chlorine reacts with water and when it is under bright sunlight
Cl2 + H2O -><- HClO + HCl
in bright sunlight :
2Cl2(g) + 2H2O(l) -> 4HCl(aq) + O2(g
Observations when period 3 elements react with oxygen
Sodium
- burns with a yellow flame and produces a white solid
Magnesium, Aluminium, Silicon, Phosphorus
- burn with a white flame to give a white solid
Sulfur
- burns with a blue flame to form a colourless gas
Explain why sodium oxide forms an alkaline solution when it reacts with water
Sodium oxide contains O2– ions
These O2– ions react with water forming OH– ions
Na2O(s) + H2O(l) -> 2Na+(aq) + 2OH-(aq)
pH of aluminium oxide and silicon dioxide
Aluminium Oxide and Silicon Dioxide are both insoluble in water pH is 7 as there is no reaction to make the water acidic or alkaline.
How do the acid/base properties of the P3 oxides change going across the period?
Across the period the oxides change from being basic to neutral to acidic
What is the relationship between the bonding and acid/base properties of the period 3 oxides?
- The oxides which are IONICALLY bonded tend to be ALKALINE
- The oxides which are COVALENTLY bonded tend to be ACIDIC
Describe a test you could carry out in a test tube to distinguish between sodium
oxide and phosphorus oxide (P4O10)
- react solution with water
- use a pH meter
- sodium oxide has a higher than phosphorus oxide
- sodium oxide forms sodium hydroxide when it reacts water
(Na2O + H2O -> 2NaOH) - pH of sodium oxide is 12 to 14
- Phosphorus oxide forms phosphoric acid when it reacts with water (P4O10 + 6H2O -> 4H3PO4)
- Phosphoric oxide has pH between -1 and 2
Write an equation for the reaction of sulfur trioxide with potassium hydroxide
solution.
SO3 + 2KOH -> K2SO4 + H2O
Or
SO3 + KOH -> KHSO4
Draw the displayed formula of the undissociated acid formed when
sulfur dioxide reacts with water.
Reaction is SO2 + H2O -> H2SO3
