22.Periodicity Flashcards
Na, Mg and Al…
- are metallic
- shiny when exposed to air
- conduct electricity
- react with dilute acids to give hydrogen and salts
Si…
- is a metalloid
- conducts electricity to some extent
P, S and Cl
- are non metals
- do not conduct electricity
- low melting and boiling points
What are the only metal elements in period 3 that react with cold water
- sodium
- magnesium
What is the only non metal that reacts with water
Chlorine
Describe the reaction between water and sodium
- vigorous
- sodium floats on the surface of the water
- fizzes rapidly
- melting because of the heat released in the reaction
- strong alkaline solution of sodium hydroxide is formed
What is the equation of the reaction between sodium and water
2Na (s) + 2H2O (l) —> 2 NaOH (aq) + H2 (g)
Describe the reaction of magnesium and water
- very slow at room temperature
- only few bubbles of H2 formed after a few days
- resulting solution less alkaline as magnesium hydroxide is only sparingly soluble
Write the equation of the reaction between magnesium and water
Mg (s) + 2H2O (l) —-> Mg(OH)2 (aq) + H2 (g)
Write the equation of the reaction between magnesium and steam
Mg (s) + H2O (g) —> MgO (s) + H2 (g)
How fast is the reaction between Mg and steam relative to Mg and water
Much faster
What type of reactions is the reaction between Na/Mg and water
Redox reaction
How can the oxides of elements in group 3 be prepared
By a direct reaction of the element with oxygen
Write the equation of the reaction for when sodium burns completely in air
2Na (s) + 1/2 O2 (g) —-> Na2O (s)
What colour is sodium oxide
White
Write the equation of the reaction for when magnesium burns completely in air
2Mg (s) + O2 (g) —-> 2MgO (s)
What colour is magnesium oxide
White
What colour are the flames of Na and Mg when burned
Na= yellow Mg= white
Write the equation of the reaction for when aluminium burns completely in air
4Al (s) + 3O2 (g) —> 2AlO3 (s)
What colour is aluminium oxide
White
Why is aluminium a reactive metal but appears to be unreactive
- it is always coated with a strongly bonded surface layer of oxide
- preventing it from further reaction
Write the equation of the reaction for when silicon burns completely in air
Si (s) + O2 (g) —> SiO2 (s)
Write the equation of the reaction for when phosphorus burns completely in air
4P (s) + 5O2 (g) —> P4O10 (s)
What is the difference between red and white phosphorus when reacting with oxygen
- red must be heated before it will react
- white spontaneously ignites in air and white smoke of phosphorus pentoxide is given up
In a limited supply of oxygen what is formed in the reaction of P and O2
P2O3
What colour is sulfur when it burns
Blue flame
Write the equation of the reaction for when sulfur burns completely in air
S (s) + O2 (g) —> SO2 (g)
Why do Na Mg and Al oxides have high boiling points
They are giant ionic lattices where the bonding extends throughout the compound. Strong electrostatic forces
What metal oxide shows covalent character
- Aluminium oxide
- Al high charge density can approach closely to O2- and distort electron cloud
Why does silicon oxide have a high melting point
- Giant covalent structure
- bonding extends throughout throughout the structure
What do phosphorus and sulfur oxides exist as
Separate covalently bonded molecules
Why do phosphorus and sulfur oxides have a low boiling point
-intermolecular forces are weak van der Waals and dipole dipole forces
What is the trend in melting points with SO3 P4O10 and SO2
P4O10 > SO3 > SO2
What are sodium and magnesium oxides
Bases
Describe the reaction between sodium oxide and water
- gives sodium hydroxides
- a strongly alkaline solution
Write the equation of the reaction for when sodium oxide reacts with water
Na2O (s) + H2O (l) —-> 2Na+ (aq) + 2OH- (aq)
Describe the reaction between magnesium oxide and water
- gives magnesium hydroxide
- which is sparingly soluble
- produces a somewhat alkaline solution
Write the equation of the reaction for when magnesium oxide reacts with water
MgO (s) + H2O (l) —> Mg2+ (aq) + 2OH- (aq)
What two oxides are insoluble in water
Aluminium oxide
Silicon dioxide
Describe the trend in melting points in period 3 oxides
MgO > Al2O3 > SiO2 > Na2O > P4O10 > SO3 > SO2
Why does MgO have a higher boiling point then Al2O3
Due to packing
Non-metals oxides typically form what with water
An acidic solution
Write the equation of the reaction for when phosphorus oxide reacts with water
P4O10 (s) + 6H2O (l) —-> 4H3PO4 (aq)
Describe the reaction between phosphorus oxide and water
- reacts violently with water
- to produce acidic solution of phosphoric (V) acid
Write an equation for the first stage of ionisation of phosphoric (V) acid in water
H3PO4 (aq) H+ (aq) + H2PO4- (aq)
Describe the reaction between sulfur dioxide and water
- sulfur dioxide is fairly soluble in water
- reacts with water to give acidic solultion of sulfuric (IV) acidic
Write the equation of the reaction for when sulfur dioxide reacts with water
SO2 (g) + H2O (l) —> H2SO3 (aq)
Write an equation for the ionisation of sulfuric (IV) acid in water
H2SO3 (aq) H+ (aq) + HSO3- (aq)
Describe the reaction between sulfur trioxide and water
- reacts violently
- to produce sulfuric (VI) acid
Write the equation of the reaction for when sulfur trioxide reacts with water
SO3 (g) + H2O (l) —> H2SO4 (aq)
Write an equation for the ionisation of sulfuric (VI) acid in water
H2SO4 (aq) —> H+ (aq) + HSO4 - (aq)
Using bonding and structure explain why sodium oxide reacts with water
- sodium oxide contains oxide ion O2- which is a very strong base
- so readily reacts with water to produce hydroxide ions
Using bonding and structure explain why magnesium oxide reacts with water
- magnesium oxide contains oxide ion which is a very strong base
- however its reaction with water produces a less alkaline solution than sodium oxide
- because it is less soluble than sodium oxide
Using bonding and structure explain why aluminium oxide doesn’t reacts with water
- aluminium oxide is ionic
- but because of the addition covalent character
- and strong metallic bonds (al has high charge density)
- bonding is too strong for the ions to be separated
Using bonding and structure explain why silicon dioxide doesn’t reacts with water
- silicon dioxide is giant macromolecular
- water does not affect this type of structure
Using bonding and structure explain why phosphorus and sulfur oxides reacts with water
- are covalent molecules
- are react with water to form acidic solutions
What is the general trend of solutions of oxides of period 3 elements
Go from alkaline to acidic across the period
Sodium and magnesium oxide react with acids to give
- salt
- water
Give the equation of the reaction between sodium oxide and sulfuric acid
Na2O (s) + H2SO4 (aq) —> Na2SO4 (aq) + H2O (l)
Give the equation of the reaction between magnesium oxide and hydrochloric acid
MgO (s) + 2HCl (aq) —> MgCl2 (aq) + H2O (l)
What property does aluminium oxide have
- it is amphoteric
- reacts with both acids and alkalis
Give the equation of the reaction between aluminium oxide and hydrochloric acid
Al2O3 (s) + 6HCl (s) —-> 2AlCl3 (aq) + 3H2O (l)
Give the equation of the reaction between aluminium oxide and sodium hydroxide
Al2O3 (s) + 2NaOH (aq) + 3H2O —> 2NaAl(OH)4 (aq)
What are the conditions of the reaction between aluminium oxide and sodium hydroxide
- hot ,
- concentrated,
- sodium hydroxide
What can silicon dioxide act as
A weak acid with strong bases
Give the equation of the reaction between silicon dioxide and sodium hydroxide
SiO (s) + 2NaOH (aq) —> Na2SiO3 (aq) + H2O (l)
What are the conditions of the reaction between silicon dioxide and sodium hydroxide
- hot
- concentrated
- sodium hydroxide
Give the overall equation of the reaction between H3PO4 and sodium hydroxide
3NaOH (aq) + H3PO4 (aq) —-> Na3PO4 (aq) + 3H2O (l)
Why is the reaction of phosphorus pentoxide and NaOH basically the reaction of H3PO4 and sodium hydroxide
H3PO4 is formed when P4O10 reacts with water
Give the 3 equation of the reaction between H3PO4 and sodium hydroxide
H3PO4 (aq) + NaOH (aq) —> NaH2PO4 (aq) + H2O (l)
NaH2PO4 (aq) + NaOH (aq) —> Na2HPO4 (aq) + H2O (l)
Na2HPO4 (aq) + NaOH (aq) —> Na3PO4 (aq) + H2O (l)
Give the equations of the reaction between sodium hydroxide and sulfur dioxide
SO2 (aq) + NaOH (aq) —> NaHSO3 (aq)
NaHSO3 (aq) + NaOH (aq) —-> Na2SO3 (aq) + H2O (l)