Chemistry Form 2

Contents

1. 1. Oxygen

   1 tests 15 questions

   Topic lessons

   • Occurrence and laboratory preparation of oxygen
   • Properties and test for oxygen
   • Reactions of oxygen with elements
   • Types of oxides
   • Industrial production and uses of oxygen
   • Summary

   Occurrence Oxygen (symbol O, molecule O 2 ) is the most abundant element in the earth's crust, where it is combined in rocks, sand (silicon dioxide) and water. Free oxygen makes up about 21% of air by volume. It is produced by green plants during photosynthesis. Laboratory preparation The common method is to decompose…

2. 2. Hydrogen

   1 tests 16 questions

   Topic lessons

   • Occurrence and laboratory preparation of hydrogen
   • Properties and test for hydrogen
   • Hydrogen as a reducing agent: oxidation and reduction
   • Uses of hydrogen
   • Summary

   Occurrence Hydrogen (H 2 ) is the lightest element. Very little free hydrogen exists in air, but it is found combined in water, acids, petroleum, natural gas and all living things. The sun is made mostly of hydrogen. Laboratory preparation Hydrogen is prepared by reacting zinc granules with dilute hydrochloric acid or…

3. 3. Water

   1 tests 16 questions

   Topic lessons

   • Occurrence of water and the water cycle
   • Properties of water and tests for water
   • Reactions of water with metals
   • Water treatment and safe drinking water
   • Uses of water, water pollution and conservation
   • Summary

   Occurrence and the water cycle Water (H 2 O) covers about 70% of the earth's surface in oceans, lakes (such as Lake Victoria and Lake Tanganyika), rivers, ice and underground. The water cycle moves water continuously: evaporation from water bodies, transpiration from plants, condensation into clouds, precipitation…

4. 4. Fuels and Energy

   1 tests 17 questions

   Topic lessons

   • Fuels and their types
   • Charcoal and biogas
   • Characteristics of a good fuel and heat value
   • Sources of energy and the effects of fuel use
   • Summary

   What is a fuel? A fuel is a substance that burns in air (oxygen) to release useful energy , mainly as heat and light. Most fuels contain carbon and hydrogen. When they burn completely they form carbon dioxide and water. Types of fuels Solid fuels: firewood, charcoal, coal, sawdust. Liquid fuels: petrol, kerosene…

5. 5. Atomic Structure

   1 tests 16 questions

   Topic lessons

   • The development of atomic theory
   • Subatomic particles, atomic number and mass number
   • Electron arrangement
   • Ions
   • Isotopes and relative atomic mass
   • Summary

   The atom An atom is the smallest particle of an element that can take part in a chemical reaction. Atoms are made of three subatomic particles : Particle Relative mass Charge Location Proton 1 +1 Nucleus Neutron 1 0 Nucleus Electron 1/1840 (almost 0) −1 Shells (energy levels) around the nucleus An atom is electrically…

6. 6. Periodic Classification

   1 tests 16 questions

   Topic lessons

   • History of the periodic table and the periodic law
   • Groups and periods
   • Group I and Group II metals
   • Group VII (halogens) and Group VIII (noble gases)
   • Trends across a period and the transition metals
   • Summary

   The periodic table The periodic table arranges elements in order of increasing atomic number . Elements with similar properties fall in the same vertical column. Early work by Döbereiner (triads), Newlands (octaves) and Mendeleev (who arranged elements by atomic mass and left gaps for undiscovered elements) led to the…

7. 7. Formulae, Bonding and Nomenclature

   1 tests 17 questions

   Topic lessons

   • Chemical symbols, valency and radicals
   • Writing chemical formulae and equations
   • Ionic (electrovalent) bonding
   • Covalent and dative bonding
   • Metallic bonding and comparing types of bonding
   • Naming chemical compounds (nomenclature)
   • Summary

   Symbols, valency and radicals Each element has a chemical symbol , e.g. H, O, Na (sodium), K (potassium), Fe (iron), Cu (copper). Valency is the combining power of an element or radical – the number of electrons an atom loses, gains or shares when it forms a compound. A radical is a group of atoms that acts as a single…