Unit 2: Section 3- Period 3 Elements (2.4) Flashcards
What subshell is the outer electron in in Mg and Na?
s subshell
What are the different reactions between magnesium and sodium with water?
sodium more reactive, more readily ionises
magnesium reacts slowly with cold water
State the reaction between sodium and cold water
2Na + 2H2O → 2NaOH + H2
State the reaction between magnesium and cold water
Mg + 2H2O → Mg(OH)2 + H2
State the reaction between magnesium and steam
Mg (s) + H2O (g) → MgO (s) + H2 (g)
How do the period 3 elements react with oxygen?
they all form oxides (except argon) that take up their highest oxidation state
What is the exception for sulphur in oxidation states when reacting with oxygen?
sulphur forms an oxide where the oxidation state of sulphur is +4
What is the oxidation state of the period 3 element in an oxide?
+3 (except sulphur)
What visible changes can you see when sodium reacts with oxygen?
- white solid formed
- yellow flame
State the equation of sodium reacting with oxygen
4Na (s) + O2 (g) → 2Na2O (s)
What colour flame do magnesium, aluminium, silicon and phosphorous burn with?
white flame
What colour flame does sulphur burn with?
blue flame
State the equation between sulphur and oxygen
S (s) + O2 (g) → SO2 (g)
State the equation for magnesium reacting with oxygen
2Mg (s) + O2 (g) → 2MgO (s)
State the equation for aluminium reacting with oxygen
4Al (s) + 3O2 (g) → 2Al2O3 (s)
State the equation for silicon reacting with oxygen
Si (s) + O2 (g) → SiO2 (s)
State the equation for phosphorous reacting with oxygen
4P (s) + 5O2 (g) → P4O10 (s)
What are properties of sulphur dioxide (SO2)
acidic, choking gas
What are the three giant ionic lattice structures of period 3 oxides?
Na2O, MgO, Al2O3
Describe the structure of SiO2
macromolecular, giant covalent oxide
Name the structure of P4O10 and SO2
simple molecular structures
How do the structures of period 3 metal oxides effect the melting points?
these different structures lead to period 3 metal oxides having different melting points
What type of melting point do ionic metal oxides have?
high
Explain the trend in melting point from Na2O to Al2O3
melting point increases due to the increased charge of the cation, which makes the electrostatic forces even stronger
What happens to the trend in melting point after Al2O3?
there is an increase, as SiO2 is macromolecular, with very strong covalent bonds, and a very high MP
What type of melting point does SiO2 have?
very high, strong covalent bonds, high energy needed to break
What happens to the trend in melting point after SiO2?
it drops
What type of melting point does P4010 and SO2 have?
lower melting point because they are simple molecular oxides
P4O10 has higher than SO2 because of more electrons, so larger van der waals.
What do metal ionic oxides form when they react with water?
hydroxides which are alkaline
State the reaction between Na2O and water, and the pH of the product
Na2O + H2O → 2NaOH
pH of 13
State the reaction between MgO and water, and the pH of the product
MgO (s) + H2O (l) → Mg(OH)2 (s)
pH of 9
Explain why the pH of Mg(OH)2 is lower than 2NaOH
because Mg(OH)2 is only slightly soluble, so it only slightly dissociates
difference in solubility due to Mg ion being smaller, so it has a stronger lattice, so fewer OH- ions produced
State the reaction between phosphorous oxide and water, and give the pH of the product
P4O10 (s) + 6 H2O (l) → 4H3PO4 (aq)
pH of 0
State the reaction between SO2 and water, and give the pH of the product
SO2(g) + H2O (l) → H2SO3 (aq)
pH of 3
State the reaction between SO3 and water, and give the pH of the product
SO3 (g) + H2O (l) → H2SO4 (aq)
pH of 0
What are the three types of oxides?
acidic
basic
amphoteric
What period 3 oxides are examples of basic oxides?
Na2O
MgO
What period 3 oxides are examples of acidic oxides?
P4O10
SO2
SO3
What period 3 oxides are examples of amphoteric oxides?
Al2O3
What happens to period 3 basic oxides in reactions?
react with acids to form a salt and water
What happens to period 3 acidic oxides in reactions?
react with bases to form salts
What happens to period 3 amphoteric oxides in reactions?
react with acids or bases
they can act as both an acid an an alkali