Group Ii, S-block

18/09/08 Periodicity- S-block/Group II Solubility: How much it will dissolve in a liquid Metal Magnesium Calcium Barium Strontium Lithium Sodium Potassium

Observation when metal added to water No immediate visible reaction Fizzing (effervesce) Effervesce, exothermic Effervesce, immediate effect Effervesce Melted, caught fire, effervesce Burnt with a lilac flame, ‘spat’

Chemical equation Mg(s)+2H₂O -> Mg(OH)₂+H ₂ Ca+2H₂O -> Ca(OH)₂+H₂ Ba+2H₂O -> Ba(OH)₂+H₂ Sr+2H₂O -> Sr(OH)₂+H₂ 2Li+2H₂O -> 2Li(OH)+H₂ 2Na+2H₂O -> 2Na(OH) +H₂ 2K+2H₂O -> 2K(OH)+H₂

General equation for group 2 metal reacting with water: M(s) + 2H₂O (l) M(OH)₂ (aq) + H₂(g) • The reactivity of the group 2 elements increases as you go down the group. • The group 1 elements are more reactive then group 2. Why? • The electrons are further away from the nucleus sp there is less of a pull; they are easier to knock out. • Group 1 has a lower positive charge.

pH Acid- Hydrogen ion makes it an acid, H⁺-just a proton; Proton donor. Base- A proton acceptor. Alkali- Soluble base- OH⁻ Therefore… All alkalis are bases but not all bases are alkalis (because some of the bases are insoluble).

Group II Hydroxides and Oxides General Equation: M(OH)₂-Hydroxides, MO-Oxides. They are only sparingly soluble. They are only sparingly soluble, but become more soluble as you go down the group and so they increase in alkalinity. Metal + Acid = Salt + Water.

Group II Carbonates General equation: MCO₃

pH 9 11 12/ 13 11/ 12 11 13/ 14 13/ 14

When heated the decompose forming the oxide and carbon dioxide. They become harder to decompose you move down the group. They decrease in solubility as you go down the group.