REACTIONS OF PERIOD 3 OXIDES Flashcards
(22 cards)
What are the metal oxides of period 3? (3)
sodium, magnesium and aluminium oxides
What is the general structure of the metal oxides in period 3? (1)
they form giant ionic lattices where the bonding extends throughout the compound. This results in high melting points
Explain the structure of aluminium oxide. (1)
the bonding in aluminium oxide is ionic but has come covalent character because aluminium forms a very small ion with a large positive charge and so can approach closely to the O2- and distort its electron cloud so the bond has some covalent character.
How do we predict the ionic character of a bond? (1)
by considering the difference in electronegativities between two atoms, the bigger the difference the greater the ionic character of the bond
What are the non-metal oxides of period 3? (3)
Silicon, phosphorus and sulphur oxide.
describe the structure of silicon oxide. (2)
has a giant covalent (macromolecular) structure, the bonding extends throughout the giant structure but it is covalent. This compound has a high melting point due to the many strong covalent bonds that must be broke to melt.
explain the structure of phosphorus and sulphur oxide. (2)
phosphorus oxides are solids, the intermolecular forces are weak van der waals and dipole-dipole forces their melting points are relatively low .
what are the basic oxides of period 3? (2)
sodium and magnesium oxides are both bases
how does sodium oxides react with water? (1)
sodium oxide reacts with water to give sodium hydroxide solution - a strongly alkaline solution.
how does magnesium oxide react with water? (1)
magnesium oxide reacts with water to give magnesium hydroxide which is sparingly soluble in water and produces a somewhat alkaline solution
what are the insoluble oxides of period 3? (2)
aluminium oxide and silicon dioxide.
what are the acidic oxides of period 3? (1)
all of the non-metals typically form acidic bases when reacting with water.
how does phosphorus pentoxide react with water? (1)
phosphorus pentoxide reacts quite violently with water to produce an acidic solution of phosphoric acid, this ionises so the solution is acidic.
how does sulphur dioxide react with water? (1)
sulphur dioxide is fairly soluble in water and reacts with it to give an acidic solution of sulfuric acid, this partially dissociates producing H+ ions which cause the acidity of the solution.
how does sulphur trioxide react with water? (1)
sulphur trioxide reacts violently with water to produce sulfuric acid.
How does magnesium and sodium oxides react with acids and bases? (1)
sodium oxide and magnesium oxide react with only acids to give salt and water.
how does aluminium oxide react with acids and bases? (1)
aluminium oxide reacts both with acids and alkalis (its an amphoteric oxide)
how does silicon dioxide react with acids and bases? (1)
silicon dioxide will react as a weak acid with strong bases
How does phosphorus pentoxide react with acids and bases? (1)
the reactions of phosphorus pentoxide with an alkali is really the reaction of phosphoric acid because this is formed when phosphorus pentoxide reacts with water.
how does phosphorus pentoxide react with water? (1)
because of the three -OH groups and each of these has an acidic hydrogen atom, so ift will react with sodium hydroxide in three stages
how does sulphur dioxide react with acids and bases? (1)
if you add sodium hydroxide to an aqueous solution of sulphur dioxide first sodium hydrogensulphate if formed, then sodium sulphate.
