Periodicity Flashcards
Why is Sodium more reactive than Magnesium?
As the amount of energy required to remove an electron from sodium is lower than it is to remove 2 with magnesium.
State the equation for Sodium reacting with water
2Na (s) + 2H2O (l) 2NaOH (aq) + H2 (g)
What observations can be made when sodium reacts with water?
It reacts vigorously forming a ball and fizzing, forming a strong alkaline solution (pH = 12 – 14)
State the equation for Magnesium reacting with water
Mg (s) + 2H2O (l) Mg(OH)2 (s) + H2 (g)
State the equation when Magnesium reacts with steam
Mg (s) + H2O (l) MgO (s) + H2 (g)
What observations can be made when magnesium reacts with water/steam?
Few bubbles and reacts slowly with water forming a weak alkaline solution as its not very soluble (pH = 9) Much faster with steam to form magnesium oxide
Why does magnesium react slowly in water?
This is because it requires more energy to lose 2 electrons
State the equation for Sodium reacting with Oxygen
4Na + O2 –> 2Na2O
What observations can be made when sodium reacts with oxygen?
Burns with yellow-orange flame to produce white powder
State the equation for Magnesium reacting with Oxygen
2Mg + O2 2MgO
What observations can be made when Magnesium reacts with oxygen?
Burns with white flame to produce white powder
State the equation for Aluminium reacting with Oxygen
4Al + 3O2 2Al2O3
What observations can be made when Aluminium reacts with oxygen?
Burns with white flame to produce white powder
State the equation for Silicon reacting with Oxygen
Si + O2 SiO2
What observations can be made when silicon reacts with oxygen?
Burns with white flame to produce white powder
State the equation for Phosphorus reacting with Oxygen
P4 + 5O2 P4O10
What observations can be made when Phosphorus reacts with oxygen?
Burns with very bright white flame to produce white powder
State the equation for Silicon reacting with Oxygen
S + O2 SO2
What observations can be made when silicon reacts with oxygen?
Burns with blue flame & gives off choking gas
Explain the trends in the Melting Points of Period 3 oxides
- First 3 have high melting points as they form giant ionic lattices which have lots of strong attractive forces requiring a lot of energy to break.
- MgO has a higher m.p than Na2O as Mg forms 2+ ions and Na forms 1+ ions. 2+ ions more strongly to the oxygen
- Al2O3 lower as it has more covalent character therefore requires less energy to break bonds
- SiO2 has a higher melting point than the other non metal oxides and this is because it forms a giant covalent structure with many strong covalent bonds requiring a lot of energy to break
- P4O10 & SO2 have lower melting points as they form simple molecular structures with weaker intermolecular forces requiring less energy to break the bonds.
State the equation for Sodium Oxide reacting with water? What happens?
Na2O + H2O 2NaOH (aq), dissolves and forms a solution
State the equation for Magnesium Oxide reacting with water? What happens?
MgO (s) + H2O (l) Mg(OH)2 (aq), slightly soluble, some dissolves forming a solution, less soluble than Na2O due to higher lattice enthalpy
State the equation for Aluminium Oxide reacting with water? What happens?
Insoluble due to high lattice enthalpy
State the equation for Silicon Oxide reacting with water? What happens?
Insoluble due to lattice being held together by strong covalent bonds
