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Topic 6 : Groups in the Periodic table - Coggle Diagram
Topic 6 : Groups in the Periodic table
Group 1: Alkali metals
Lithium, sodium, potassium, rubidium,caesium and francium
Silvery solids that are stored in oil and handled with forceps
All have 1 electron in ths outer shell, so they have similar chemical properties
very reactive
Similar physical properties, low melting point and boiling points, very soft
Reactivity
Group 1 metals readily loose their single outer electron to form a 1+ ion
The more easily a metal looses its outer electron the more reactive it is.
As you go down group 1, the reactivity of the alkali metals increases
The outer electron is more easily lost because its further from the nucleus so is less strongly attracted to it and less energy is needed to remove it
They form ionic compounds. The single outer electron is easily lost, so they don't form covalent bonds
Reactions with water
Alkali metal + water --> metal hydroxide + hydrogen
Sodium reacts to form sodium hydroxide, fizzes rapidly
Potassium reacts to form potassium hydroxide. Burns to porduce a lilac flame
Lithium reacts to form lithium hydroxide. It moves around the surface of the water, fizzing steadily
Group 7: Halogen basics
Reactivity
Reactivity decreases because it gets harder to attract the extra electron to fill the outer shell when it's further away from the nucleus due to lower attraction forces
The easier it is for a halogen atom to attract an electron, the more reactive it is
As you go down group 7, the reactivity decreases
As you go down Group 7, melting points and boiling points increase
Exist as diatomic molecules, sharing one pair of electrons in a covalent bond
All have 7 electrons in their outer shell
Fluorine, chlorine, bromine, iodine and astatine
Halogen reactions with metals
Halogens will react vigorously with some metals to form salts called metal halides
Chlorine reacts with sodium to form sodium chloride
Bromine reacts with potassium to form potassium bromide
Test for Chlorine
Chlorine turns damp litmus paper white
Turns from blue to white
Halogen displacement reactions
A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt
Chlorine is more reactive than bromine, so it will displace bromine from an aqueous solution of its salt. Chlorine is reduced, bromine is oxidised
Cl2 + 2KBr --> Br2 + 2KCl
Fluorine is more reactive than bromine, so it will displace bromine from an aqueous solution of its salt. Fluorine is reduced, Bromine is oxidised
F2 + 2NaBr --> Br2 + 2NaF
A less reactive halogen will not displace a more reactive halogen
Displacement reactions are redox reactions, both reduction and oxidation occur
More reactive halogen displaces less reactive one, forming a negative ion, meaning it is reduced
Less reactive halogen is oxidised as it loses electrons and goes from a negative ion to an atom with no charge
Appearances
Alkali metals
Lithium: Grey solid, shiny on the inside
Sodium: Silvery white metal
Potassium: Silvery white
Halogens
Chlorine: green gas
Bromine: Orange liquid
Iodine: Grey solid
Halogens in solution
Bromine: Orange
Iodine: Brown
Group 0: Noble gases
Helium, Neon, Argon, Krypton, Xenon, Radon
All have a full outer shell of electrons
For every noble gas apart from Helium, there are 8 outer electrons
In helium, there are only 2 electrons in the first shell
As the outer shell is energetically stable, they don't need to give up or gain electrons to become more stable
This makes them 'inert', they dont react with anything.
They are non-flammable
At room temperature they exist as colourless, odourless, monatomic gases, single atoms not bonded to anything else
Uses of noble gases
Inertness
Noble gases are very unreactive
Argon provides an inert atmostphere in filament lamps, it stops very hot filament from burning away
Argon, krypton and xenon are used in flash photography, to stop the filament burning up in high temperature falshes
Argon and helium can be used to protect metals that are being welded. The inert atmostphere stop the hot metal reacting with oxygen
Density
Group 0 gases have low density
Helium is used in airships and part balloons. Helium is less dense than air, so will float