REVISION NOTE ON METALS
- Definition –Metals are compounds whose oxides when dissolved in water turns red litmus paper blue that is metals form basic oxide.
They are found in groups 1,2,3 and between groups 2and 3 in the periodic table. Their atoms loose electrons to form posture. Ions. e.g. Sodium, copper, aluminum, Manganese Iron etc.
All metals are solids except mercury (Liquid metal)
- Properties (a). physical
- Good conductors of heat and electricity
- Malleable and ductile
- Metallic luster, hence can be polished
- High tensile strength
- High densities
- High melting/boiling points
- Form (mainly) basic oxides
- Reducing agents/ electron donors
- Form cations (in solution), ionizes by electron loss, are all electropositive
- Metals are deposited on the cathode during electrolysis
- Metals can replace hydrogen from acids to form salt and hydrogen.
- Metals from electrovalent compounds and chlorides
- Metallic atoms are held together by metallic bonds
- Extraction of Metals
The three general methods for extracting metals from their ores are
- Electrolysis/Reduction by electrolysis
- Reactive metals (K, Na, Ca, Mg, Al) High in the electrochemical series are extracted by this method
- Reduction with Carbon (II) oxide/Coke/Carbon
- The less electropositive metals (Zn, Fe, Sn , Pb, Cu) low in the electrochemical series and moderately reactive are extracted by this method.
- The least reactive metals especially Hg, Ag, and Au whose ore contains free elements are extracted as free elements
- Equation for the reactions in the extraction of Aluminum (Electrolysis)
Factors Necessary For To Rust
(i) Air (oxygen) (ii) Moisture (water) (ii) impurities in the iron
Methods of checking rusting
- Coating the iron with protective materials we PVG oil/paint
- Galvanizing the iron i.e dipping it in a molten solution of a more electropositive metal like zinc
- Forming alloys e.g stainless steel.
An alloy is mixture of two or more metals or non-metal to get certain quality. They have high resistance to corrosion/rusting.
Examples of alloy:
- Why are metals good conductors of heat/electricity?
- Describe in detail the traction of aluminum from bauxite.
- (a) list three physical properties of metals which are related to their structure
- List three general methods of extracting metals from their ores
(b) State two differences in the chemical properties of metals and non-metals
- (a) Name one metal which reacts reversibly with steam at room temperature
(b) what is the function of calcium fluoride in the of calcium by the electrolysis of calcium chloride