Elements in period 3 smkbbst

Period 3 elements

1. ELEMENTS IN A PERIOD Periodic Table of Elements ( Pg 72)

2. Period 3 elements – Na, Mg, Al, Si, P, S, Cl and Ar

3. Elements in period 3 and the electron arrangements in all elements in period 3. Element of period 3 Na Mg Al Si P S Cl Ar Electron arrangement 2.8.1 2.8.2 2.8.3 2.8.4 2.8.5 2.8.6 2.8.7 2.8.8 + e - e - e - e - e - e - e - e - e - e - e - 2.8.1 + e - e - e - e - e - e - e - e - e - e - e - 2.8.8 e - e - e - e - e - e - e - + e - e - e - e - e - e - e - e - e - e - e - 2.8.4 e - e - e -

4. Properties of elements in Period 3 Element of period 3 Na Mg Al Si P S Cl Ar Proton number 11 12 13 14 15 16 17 18 Electron arrangement 2.8.1 2.8.2 2.8.3 2.8.4 2.8.5 2.8.6 2.8.7 2.8.8 Electronic structure Atomic radius (pm) 186 160 143 118 110 104 100 94 Physical state at room temperature Solid Solid Solid Solid Solid Solid Gas Gas Electronegativity 0.9 1.2 1.5 1.8 2.1 2.5 3.0 -

5. The changes in the properties of elements across Period 3 The physical state of elements in period 3 are solids except chlorine and argon which are gases . Atomic radius of elements decreases due to increasing nuclei attraction on the valence electrons. Electronegativity of elements increases due to increasing nuclei attraction on the valence electrons and the decrease in atomic size .

6. The change of properties of the oxides of elements across Period 3 Sodium and magnesium form basic metal oxides . Aluminium form amphoteric oxide . [ An amphoteric oxide can react with both acids and bases to form salts and water ]. Silicon, phosphorus, sulphur and chlorine form acidic non-metal oxides .

7. THE ACID-BASE PROPERTIES OF THE OXIDE OF PERIOD 3 ELEMENTS Oxide Observation Inference With water pH Value With NaOH With HNO 3 Na 2 O Soluble. Forms colourless solution 13 - 14 Insoluble Soluble. Forms colourless solution Strong base. Strong alkali. MgO Slightly soluble. Colourless solution 8 - 9 Insoluble Soluble. Forms colourless solution A basic oxide. Weak alkali. Al 2 O 3 Insoluble 7 Soluble. Forms colourless solution Soluble. Forms colourless solution An amphoteric oxide, with acidic and bacic properties. SiO 2 Insoluble 7 Soluble. Forms colourless solution Insoluble An acidic oxide.

8. THE ACID-BASE PROPERTIES OF THE OXIDE OF PERIOD 3 ELEMENTS Oxide Observation Inference With water pH Value With NaOH With NH 3 P 4 O 10 Soluble. Forms colourless solution 2 - 3 Soluble. Forms colourless solution Insoluble An acidic oxide. SO 2 Soluble. Forms colourless solution 2 - 3 Soluble. Forms colourless solution Insoluble Form an acid. An acidic oxide. Cl 2 O 7 Soluble. Forms colourless solution 1 Soluble. Forms colourless solution Insoluble Strong acid formed. An acidic oxide. CONCLUSION The oxide of elements in period 3 change from basic to amphoteric and then to an acidic nature as we go across the period towards the right.

9. Predict the changes in the properties of elements across other periods The elements changes from : State - Solid to gas Metal to non-metal Conductor to non-conductor

10. The following properties decreases from left to right : Atomic size Melting points Boiling point

11. The following properties increase from left to right : Proton number The number of valence electron Electronegativity

12. Semi metals @ metalloid Semi-metals or metalloids are weak conductors of electricity . Semi-metals such as silicon and germanium are used as semiconductors . Semiconductors are used to make diodes and transistors . Diodes and transistors are used to making of microchips . Semiconductors enables us to surf inter net and watch television.

13. USES OF SEMI METALS IN INDUSTRY Uses of semi metals