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CHEMISTRY (CORE)

Group 1 ­ Alkaline Earth Metals

Reactions of alkali metals with water

When a group 1 metal reacts with water, a metal hydroxide and hydrogen are
formed.
The metal hydroxide then dissolves in water to form an alkaline solution.

E.g.
potassium + water = potassium hydroxide + hydrogen…

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Group 7 ­ Halogens
Reactivity decreases down the group
Form diatomic molecules (i.e. F2, Cl2, Br2 etc)
Brittle and crumbly when solid
Poor conductors of heat and electricity

Reactions of Halogens with metals
Halogens react with metals to produce ionic salts.
The halogen gains an electron (forming a halide with…

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The easier it is for electrons to be lost




The Transition Metals
Found between groups 2 and 3, these metallic elements include iron (Fe),
copper (Cu), platinum (Pt), mercury (Hg), chromium (Cr) and zinc (Zn).

These metals...
Are hard and mechanically strong (except mercury ­liquid)
Have higher densities and melting…

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Acids and Alkalis

Some compounds react with water to produce acidic or alkaline aqueous
solutions. On their own, these compounds sometimes do not exhibit any acid or
alkaline characteristics. For these compounds, water must be present for the
substance to act as an acid or base.




Acids
All acids dissociate…

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Sodium hydroxide sodium ions + hydroxide ions
NaOH(aq) Na+(aq) + OH-(aq)

An acid can be defined as a proton donor.
An alkali (or base) can be defined as a proton acceptor.
An acid cannot donate a proton unless there is an appropriate base to
accept it.
Strength of acids and…

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Water

Purification of water
Passed through a filter bed to remove solids
Chlorine gas added to kill microorganisms
Passed through a filter of carbon, silver and ion exchange resins to
reduce salt levels.
(Could also be distilled, but this is expensive)

Solubility of compounds
Most ionic compounds are soluble (i.e.…

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Joules and Calories
Energy is measured in Joules (J)
It takes 4.2 J of energy to heat up 1g of water by 1°C.
4.2J = a calorie.
Calorimetry is the process of burning substances to measure their
energy content based on the water temperature change they cause.
Tests
Flame tests…

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Sulfate ions:
Add barium chloride solution and dilute hydrochloric acid.
White barium sulphate will precipitate out.
Barium ion + Sulphate ion = Barium sulphate
2+ 2-
Ba (aq) SO4 (aq) BaSO4(s)


Nitrate ions:
Add aluminium powder and sodium hydroxide solution.
Nitrate ions are reduced to form ammonia (NH3), which turns…

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Chemical Reactions
Ionic bonds tend to form between groups 2 and 6, and 1
and 7, between metals and non-metals.

Ionic compounds stay together due to strong electrostatic force
between the oppositely charged ions. This force acts equally in all
directions between ions, which is why the ions are held…

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The Haber Process
Uses:
Nitrogen from air (liquid form is fractionally distilled)
Hydrogen from natural gas

Passed over an iron catalyst at 450C and 200 atmospheres.
Nitrogen + Hydrogen
Ammonia
N2 (g) + 3 H2 (g)
2 NH3 (g)
Exothermic and Endothermic Reactions
In exothermic reactions, energy is given out.…

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