Groups in the Periodic Table

What are the alkaline metals & what are their physical properties?

Group 1 elements that are:

Similar to typical metals:*

• good conductors of heat & electricity

• shiny when freshly cut

  Different to typical metals:

• soft

• low melting points

• low density ( Lithium, Sodium, Potassium less dense than water, float)

What is the word equation of an alkali metal reacting with water?

alkali metal + water ——> alkaline metal hydroxide + hydrogen

e.g: sodium* 2Na(s) + water 2H2O(l) ——> sodium hydroxide 2NaOH(aq) + hydrogen H2(g)

What are the alkaline metals & what are their physical properties?

Group 1 elements that are:

Similar to typical metals:*

• good conductors of heat & electricity

• shiny when freshly cut

  Different to typical metals:

• soft

• low melting points

• low density ( Lithium, Sodium, Potassium less dense than water, float)

What is the word equation of an alkali metal reacting with water?

alkali metal + water ——> alkaline metal hydroxide + hydrogen

e.g: sodium* 2Na(s) + water 2H2O(l) ——> sodium hydroxide 2NaOH(aq) + hydrogen H2(g)

What is the word equation of an alkali reacting with chlorine gas?

alkali metal + chlorine gas ——> metal chloride salt

e.g: sodium Na(s)+ chlorine(g) ——> sodium chloride (aq)

What is the word equation of an alkali reacting with oxygen?

alkali metal + oxygen ——> metal oxide

• lithium + oxygen ——> lithium oxide Li2O

• sodium + oxygen ——> sodium oxide Na2O or sodium peroxide Na2O2

• potassium + oxygen ——> potassium peroxide K2O2 or potassium superoxide KO2

What is the reactivity of the alkali metals?

Reactivity increases down the group & melting/ boiling points decrease:

• Lithium fizzes steadily

• Sodium melts into a ball from the heat released in the reaction & fizzes rapidly

• Potassium gives off sparks & the hydrogen produced burns with a lilac- coloured flame

• Rubidium, Caesium & Francium ignite spontaneously, explosively

What happens whilst an alkali metal is reacting?

• Atoms want to have a completely full outermost shell to be stable

• Alkali metals in Group 1 so have one outermost electron

• Loses singular electron on outermost shell to become a 1+ ion

Why does reactivity increase further down alkali metals?

• Increase of electron shells from different periods

• Distance between outermost electron & nucleus increases

• Weakens attractive force from positive nucleus & negative electron

• Can easily be lost

What compound do alkali metals usually form?

Ionic compounds with non- metals

How are Lithium, Sodium & Potassium stored?

In oil to keep air & water away

What are the halogens & what are their appearances like?

Group 7 non-metals that are covalent molecules (diatomic molecules)

• Fluorine F2- pale yellow gas

• Chlorine Cl2- yellow-green gas

• Bromine Br2- red-brown liquid

• Iodine I2- dark grey solid, forms purple vapour when warmed

What happens whilst a halogen is reacting?

• Atoms wants to have a full outermost shell to become stable

• Halogens in Group 7 so have seven electrons on outermost shell

• Gain one electron to become a 1- ion

Why does reactivity decrease further down the halogens?

• Amount of electron shells increase

• Distance between nucleus & electrons on outermost shell increases

• Weakens forces of attraction between positive nucleus & negative electrons

• More difficult to pull in additional electron to have full outer shell

How do halogens form ionic bonds with metals?

When a halogen gains an electron to become stable it becomes a halide:

• Fluoride

• Chloride

• Bromide

• Iodide

  e.g sodium 2Na(s) + chlorine Cl2(g) ——> sodium chloride 2NaCl(s)

• sodium burns with an orange flame, forming white sodium chlordie

  iron 2Fe(s) + 3Cl2(g) —- > iron(III) chloride 2FeCl3 (s)

What is a halogen displacement reaction?

A more reactive halogen displaces a less reactive halogen from its compound

How can you investigate displacement reactions of halogens?

Adding a halogen to a metal halide solution, then seeing if the mixture darkens e.g:

• Chlorine in ‘chlorine water’ displaces bromine from aqueous solution bromide solution

• Balanced equation: Cl2 (aq) + 2NaBr(aq) —> 2NaCl(aq) + Br2(aq)

• Ionic equation ( Na+ ions are spectator ions) Cl2(aq) + 2Br-(aq) ——> 2Cl-(aq) + Br2(aq)

What are the noble gases & what is their reactivity like?

Group 0 elements

• Chemically inert (unreactive) because have full outer shell so don’t need to gain, lose or share electrons

What the uses of helium?

Lifting gas in party balloon & airships

Why?

• Helium is less dense than air so the balloons/ airships rise

• Non-flammable so does not ignite

What are the uses of argon, krypton & xenon?

Filling gas in filament lamps

Why?:

• Metal filament becomes hot enough to glow

• Inert gases stop it from burning away

What is another use of argon?

Shield gas during welding

Why?:

• Argon is denser than air so it keeps air away from the metal

• Inert so metal does not oxidise