1. Title: Lesson 4 Period 3 Oxides Learning Objectives: Understand and explain the trend in acid-base behaviour of the period 3 oxides Complete an experiment to demonstrate the amphoteric nature of aluminium oxide

2. Refresh Which properties of the alkali metals decrease going down group 1? A.First ionization energy and reactivity B.Melting point and atomic radius C.Reactivity and electronegativity D.First ionization energy and melting point

3. The Period 3 Oxides ElementFormula of oxide Structure Reaction of oxide with waterAcid/base nature Sodium*Na 2 OGiant IonicNa 2 O + H 2 O  2NaOHStrongly basic Magnesium*MgOGiant IonicSlight: MgO + H 2 O  Mg(OH) 2 Weakly basic AluminiumAl 2 O 3 Giant IonicAmphoteric SiliconSiO 2 Giant Covalent (Metalloid) Very weakly acidic Phosphorous*P 4 O 10 Molecular CovalentP 4 O 10 + 6 H 2 O  4 H 3 PO 4 Strongly acidic Sulphur*SO 2 SO 3 Molecular Covalent SO 3 + H 2 O  H 2 SO 4 Strongly acidic Chlorineno direct reaction but: Cl 2 O 7 Molecular Covalent Cl 2 O 7 + H 2 O  2 HClO 4 Strongly acidic Argonno oxides  There is a gradual transition from basic to acidic character, reflecting a gradual transition from metallic to non-metallic nature Note: you will only be tested on the elements marked with an asterisk, *

4. 13.3 OXIDES WITH ACIDS & BASES pH OF PERIOD 3 OXIDES: Na 2 O MgO Al 2 O 3 SiO 2 P 4 O 10 SO 2 SO 3

5. 13.3 OXIDES WITH ACIDS & BASES A CLASSIC The equation for neutralising an acid with a base is a classic Acid + Base  Salt + Water It’s no different for Period 3 oxides You will be expected to write the equations

6. SODIUM & MAGNESIUM: Na 2 (s) + H 2 O(l)  2NaOH (aq) (Alkaline solution formed) These oxides are basic so will neutralise acids. E.g. Sodium oxide reacts with hydrochloric acid to form Sodium chloride and water Na 2 O (s) + 2HCl (aq)  2NaCl (aq) + H 2 O (l) E.g. Magnesium oxide reacts with sulphuric acid to form magnesium sulphate and water MgO (s) + H 2 SO 4(aq)  MgSO 4(aq) + H 2 O (l) BASIC OXIDES Create 2 other equations for Na & Mg with different acids

7. ALUMINIUM OXIDE: Aluminium Oxide does not affect pH when added to water because it is insoluble. This is an amphoteric oxide  it can react with both acids and alkalis E.g. With sulphuric acid, aluminium sulphate is formed Al 2 O 3(s) + 3H 2 SO 4(aq)  Al 2 (SO 4 ) 3 (aq) + 3H 2 O (l) Reaction with bases: Aluminum oxide also displays acidic properties, as shown in its reactions with bases such as sodium hydroxide. Various aluminates (compounds in which the aluminum is a component in a negative ion) exist, which is possible because aluminum can form covalent bonds with oxygen. E.g. With hot, concentrated sodium hydroxide, sodium aluminate is formed Al 2 O 3(s) + 2NaOH (aq) + 3H 2 O (l)  2NaAl(OH) 4(aq) AMPHOTERIC OXIDES

8. Acidic Oxides Non metallic oxides react with water to produce acidic solutions: Phosphorous(V) oxide reacts with water to produce: Phosphorous (III) oxide reacts with water to produce: Sulphur trioxide reacts with water to produce sulphuric(VI) acid: Sulphur dioxide reacts with water to produce sulphuric(IV) acid:

9. SILICON, PHOSPHOROUS & SULPHUR: These oxides are all acidic so will neutralise bases P 4 O 10(s) + 12NaOH (aq)  4Na 3 PO 4(aq) + 6H 2 O (l) SO 2(g) + 2NaOH (aq)  Na 2 SO 3(aq) + H 2 O (l) SO 3(g) + 2NaOH (aq)  Na 2 SO 4(aq) + H 2 O (l) ACIDIC OXIDES