Elements are divided mainly into two groups on the basis of physical and chemical properties, viz. Metal and Non-metal. In this section, you will read about physical properties of metals and metal's reaction with oxygen.
Hardness: Most of the metals are hard. They do not break into pieces when hit with something. But alkali metals are exception, e.g. sodium, potassium, lithium, etc. These are very soft metals, and can be cut using knife.
Strength: Most of the metals are strong and have high tensile strength. Because of this, big structures are made using metals. Buildings, bridges, ships, airplanes, etc. are made of metals.
State: Metals are solid at room temperature. But mercury is an exception, as it is a liquid at room temperature.
Sound: Metals produce ringing sound, so, metals are called sonorous. The typical sound of metals is also known as metallic sound. Due to this, metal wires are used in making musical instruments. Bells are made of metals.
Conduction: Metals are good conductor of heat and electricity. Due to this, electric wires are made of metals, e.g. copper and aluminium.
Malleability: Metals are malleable. This means metals can be beaten into thin sheet. So, iron can be turned into sheets to make vehicle and ship. Gold and silver can be used to make ornate design for making ornaments.
Ductility: Metals are ductile. This means metals can be drawn into thin wire. Due to this, wires are made of metals.
Melting and boiling point: Metals generally have high melting and boiling points.
Density: Most of the metals have high density.
Color: Most of the metals are grey in color. But gold and copper are exceptions. Gold is yellow, while copper is reddish brown in colour.
Most of the metals form oxides when they react with oxygen. This can be sown by the followin general equation.
Metal + Oxygen ⇨ Metal oxide
Reaction of potassium with oxygen: When potassium reacts with oxygenm, it forms potassium oxide. Following equation shows this reaciton.
4K + O2 ⇨ 2K2O
Reaction of sodium with oxygen: When sodium reacts with oxygen, it forms sodium oxide. Following equation shows this reaction.
4Na + O2 ⇨ 2Na2O
Lithium, potassium, sodium, etc. are known as alkali metals. Alkali metals react vigorously with oxygen.
Reaction of magnesium with oxygen: When magnesium reacts with oxygen it gives magnesium oxide. You must have read about the experiment on burning a ribbon of magnesium. Magnesium burns with dazzling light in air. In fact, this property of magnesium makes it useful in fireworks. Following equation shows this reaction.
2Mg + O2 ⇨ 2MgO
Reaction of aluminium with oxygen: Aliminium does not react with oxygen at room temperature but it gives aluminium oxide when burnt in air. Following equations shows this reaction.
4Al + 3O2 ⇨ 2Al2O3
Reaction of zinc with oxygen: Zinc does not react with oxygen at room temperature. But it gives zinc oxide when heated strongly in air. Following equation shows this reaction.
2Zn + O2 ⇨ 2ZnO
Reaction of Iron with oxygen: Iron does not react with oxygen at room temperature. But when iron is heated strongly in air, it gives iron oxide. Following equation shows this reaction.
3Fe + 2O2 ⇨ Fe3O4
Iron fillings give sparkle in flame when burnt.
Reaction of copper with oxygen: Copper does not react with oxygen at room temperature but when heated strongly, it gives copper oxide. Following equation shows this reaction.
2Cu + O2 ⇨ 2CuO
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