3.1 The Periodic Table

-the energy required to remove one mole of electron from each atom in one mole of the gaseous element to form one mole of gaseous 1+ ions

-sodium conducts in the solid and molten states -sodium is an alkali metal so has delocalised electrons in both solid and liquid state -sodium oxide conducts when molten and not when solid -as molten sodium oxide has ions which are mobile -solid sodium oxide has ions which are fixed in position in a lattice

-carbonate ions CO3^2- -sulfate ions SO4^2- -halide ions- Cl^-, Br^-,I^-

-water and carbon dioxide and a salt

.Add a dilute strong acid to the suspected carbonate. .Collect any gas formed and pass it through limewater Positive test • Fizzing/colourless gas is produced. • The gas turns limewater cloudy.

-barium sulfate BaSO4 an insoluble salt which is aqueous

• Add dilute hydrochloric acid and barium chloride to the suspected sulfate Positive results • a white precipitate of barium sulfate is produced.

Different coloured halide precipitates

-dissolve suspected halide in water -add an aqueous solution of silver nitrate -note the colour of any precipitate formed -add aqueous ammonia to distinguish the colour , adding first dilute then concentrated -note the solubility of the precipitate in aqueous ammonia

-white precipitate -soluble in dilute aqueous ammonia

-cream precipitate -soluble only in concentrated ammonia

-yellow precipitate -insoluble in both dilute and concentrated aqueous ammonia

-the ammonium ion NH4^+

-to produce ammonia and water

• Add sodium hydroxide solution to the suspected ammonium compound and warm very gently. • Test any gas evolved with red litmus paper Positive results • Ammonia gas will turn red Litmus paper blue. • Ammonia gas has a distinctive smell. (Ammonia gas is hazardous )

-group 1 and 2 the elements have a giant metallic structure so there are strong forces between the positive ions and negative delocalised electrons -in group 13 and 14 the elements have a giant covalent structure meaning there are strong covalent bonds that have to be overcome -as well as this the nuclear charge increases as well as the number of electrons in the outer shell- causing stronger attraction -Meaning a high amount of energy is needed to overcome these bonds and forces so they have a high melting point -However between group 14 and 15 there is a sharp decrease in melting point as these elements have simple molecular structure held together by weak intermolecular forces between the molecules -in group 15 and 18 the melting points remain relatively low as they also have a simple molecular structure

• form colourless (white) compounds.

-they lose 2 electrons in redox reactions to form 2+ ions

S-block

-reactivity increases going down the group -ionisation energies show that the two outer electrons are lost more easily going down the group to barium -as each successive element has its outer electrons in a higher energy level ,has a larger atomic radius and feels more electron shielding from the positive pull of the nucleus. So they have less nuclear attraction

-they are strong reducing agents -they are oxidised in reactions to form 2+ ions

1st Mg (g)—> Mg^+(g) + e^- 2nd Mg^+(g)—-> Mg^2+(g) +e^-

-they react vigorously with oxygen -this is a redox reaction -the product is an ionic oxide for example calcium oxide CaO 2Mg +O2 ———> 2MgO

-all group 2 elements ,except beryllium, react with water to form hydroxides e.g.Mg(OH)2 And hydrogen gas -this is a redox reaction -Mg reacts with water very slowly. Moving further down the group, each metal reacts more vigorously with water