Chemistry Module 3 Explanations

Be: No reaction Mg: Requires steam Ca, Sr, Ba : Fizzing observed & metal disappears

When a group 2 element reacts, it loses 2 outer shell electrons This involves 2 ionisation energies Nuclear attraction decreases going down group So reactivity decreases

Solubility of hydroxides increase going down group As solubility increases, the resulting solutions contain more OH- ions and are more alkaline

Antiacids Ca(OH)2 Increases pH of acidic soils Carbonates used in indigestion tablets

Pale yellow gas

Pale green gas

Red-brown liquid

Grey-Black shiny solid

Pale green

Orange

Brown

Pale green layer forms

Orange layer forms

Violet layer forms

Reactivity of halogens decreases down group Atomic radius increases More inner shell shielding Lower nuclear attraction

Boiling point increases going down the group More electrons = stronger London forces More energy required to overcome London forces

Ensures water is safe to drink Used as a disinfectant

Toxic gas: respiratory irritant and fatal in large concentrations Chlorine and drinking water can react with hydrocarbons to form chlorinated hydrocarbons (carcinogens)

• Orbitals with lowest energy are filled first • Up to 2 electrons with opposite spins can fit into one orbital 3.If orbitals have same energy, then electrons are put in individual orbitals before being paired

Higher charge of ion = higher bond strength

Delocalised electrons move throughout structure, carrying charge High conductivity

High melting/boiling points Most metallic bonds are strong - large amounts of energy required to break them

Melting point increases from group 1 to group 4 Sharp decrease between group 4 and group 5 Melting points comparatively low from Group 5 to Group 8

Atomic radius More distance = weaker nuclear attraction Nuclear charge More protons = greater nuclear attraction Inner shell shielding Inner shell electrons repel outer shell electrons = lower nuclear attraction