inorganic chem; properties of period 3 elements & their oxides Flashcards
(34 cards)
Which element is more reactive, Na or Mg & why?
- Na is more reactive
- as the amount of energy required to remove an e- from Na is lower than Mg
- More energy is required for Mg to react
Reaction of Na + cold water…
- Na reacts vigorously forming a ball & fizzing
- Gas produced = H2 gas
- Alkaline solution = NaOH
Equation of Na + cold water — include state symbols
2Na (s) + 2H2O (l) → 2NaOH (aq) + H2 (g)
Reaction of Mg + cold water
- Mg reacts slowly
- forming a weak alkaline solution of Mg(OH)2 — solution is sparingly soluble so there are little OH- ions
Mg reacts much … with … forming magnesium oxide
… faster
… steam
Equation of Mg + cold water — include state symbols
Mg (s) + 2H2O (l) → Mg(OH)2 (aq) + H2 (g)
Equation of Mg + steam — include state symbols
Mg (s) + H2O (g) → MgO (s) + H2 (g)
Period 3 elements reacts with oxygen to form…
… oxides
Sodium oxide equation — include state symbols
2Na (s) + 1/2 O2 (g) → 2Na2O (s)
Magnesium oxide equation — include state symbols
Mg (s) + 1/2 O2 (g) → MgO (s)
Aluminium oxide equation — include state symbols
2Al (s) + 1 1/2 O2 (g) → Al2O3 (s)
Silicon dioxide equation — include state symbols
Si (s) + O2 (g) → SiO2 (s)
Phosphorus (V) oxide equation — include state symbols
P4 (s) + 5O2 (g) → P4O10 (s)
Sulfur dioxide equation — include state symbols
S (s) + O2 (g) → SO2 (g)
Which element does not form an oxide & what does it form?
- Sulfur
- Forms SO2 (+4 oxi number)
- or SO3 (+6 oxi number) — formed with high temp & catalyst
Period 3 elements & reactions with air
Structure & bonding of group 3 oxides affect their …
… melting points
Which oxides form giant ionic lattices & why?
- Na2O
- MgO
- Al2O3
They all have high mp
Why does MgO have a higher mp than Na2O?
- As Mg forms +2 ions & Na forms +1 ions
- the +2 ions are attracted more strongly to the oxygen
Why does Al2O3 have a lower mp than MgO?
- As the Al3+ ions distort the e- cloud of oxygen
- this means that there is some covalent character & ionic interactions
- so less energy is required to break the bonds
Why does SiO2 have a higher mp than the other metal oxides?
- Forms a macromolecular (giant covalent) structure
- has many strong covalent bonds — require lots of energy to break
- P4O10 & SO2 form simple molecular structures
- they have weaker IMF — less energy required to break the bonds
Ionic oxides when added to water form…
… alkaline solutions
Ionic oxides contain the … ions which … … from the water molecules when dissolved in solution
…O2-
… accepts protons
What pH level does an alkaline solution that is formed from sodium oxide & water have?
pH 12-14
Dissolves readily
