group trends

How to extract group 1 elements?

too reactive to be extracted from their compounds by reduction with carbon or carbon monoxide. Must be extracted from molten compounds (eg NaCl) by electrolysis

What are the physical properties of a group 1 metal?

• Soft

• Low melting and boiling points as metallic bonds are weaker

• Fresh surface is shiny but tarnishes quickly as oxide forms

• Low density so it floats on water

What is the reactivity of group 1 metals?

Very reactive so it's stored in oil to prevent reaction with oxygen and water in the air. It reacts vigorously with water forming hydrogen and metal hydroxide

What happens when potassion reacts with water?

Catches fire and hydrogen burns with a lilac flane. It pops as hydrogen ignites and gives off sparks

What happens when lithium reacts with water?

It fizzes steadily

What happens when sodium reacts with water?

It melts into a ball and fizzes quickly

Why does the reactivity of group 1 elements increases going down the group?

It is easier to lose the outer shell electrons because the further the electron us from the nucleus the weaker the attraction. It is also shielding from the attraction of the nucleus by more full inner shells and so needs more energy to remove it

How are halogens extracted?

Cl is extracted by electrolysis of NaCl solution. Br and I are extra fed from their salts by displacement using Cl2. Salts come from sea water which is then concentrated

What does chlorine look like?

Pale green gas

What does bromine look like?

Dark red liquid

What does iodine look like?

Purple solid

Why do halogens have low melting and boiling points?

They are simple covalent molecules and only weak intermolecular forces are needed to be overcome

How does the melting and boiling point increase down group 7?

As molecules get bigger the intermolecular forces beg stronger as there are more elctronss in the molecules.

How to test for chlorine?

Damp blue litmus paper turns red and is then bleached white

Uses of choorine

Kills bacteria in tap water and swimming pool water. Bleach in paper making. Production of antiseptics or anaesthetics