Metals and their Properties

TOPIC 11

Metals and their Properties

Metals have distinctive properties such as:

4. Malleability.4. Malleability.3. Strength3. Strength2. Good Thermal Conductivity2. Good Thermal Conductivity1. Electrical Conductivity1. Electrical Conductivity

Reactions of Metals

General Equation

With OxygenWith Oxygen

All metals react with Oxygen. The more All metals react with Oxygen. The more reactive the metal the quicker the reaction.reactive the metal the quicker the reaction.

In the lab the oxygen is produced by heating In the lab the oxygen is produced by heating potassium permanganate.potassium permanganate.

The brighter the glow the more the reactive the The brighter the glow the more the reactive the metal. Less reactive metals produce a duller glowmetal. Less reactive metals produce a duller glow

Metal OxideMetal OxideMetal + OxygenMetal + Oxygen

Metals + Oxygen (continued)

Potassium permanganate acts as a source of oxygen when Heated

Mg metal is placed

between two pieces of

ceramic wool

The more active the metal the brighter the glow

Reactions of Metals

Metal + H2O

With WaterWith Water

Only metals above hydrogen in the Activity Only metals above hydrogen in the Activity Series react with water.Series react with water.

In fact only the first three react with In fact only the first three react with coldcold water. water.

The remaining metals above hydrogen must be treated The remaining metals above hydrogen must be treated with with steamsteam before a reaction will take place. before a reaction will take place.

General Equation

Metal Hydroxide + HMetal Hydroxide + H22

Reactions of Metals

Metal + Acid

With AcidsWith Acids

Only Metals above Hydrogen in the Activity Series Only Metals above Hydrogen in the Activity Series

react with Acids.react with Acids.

General Equation

Salt + HydrogenSalt + Hydrogen

PopPop

When a metal is reacted with an acid it produces H2 gas which burns with a POP!

Metals and Acid (continued)

Alloys

• An Alloy is a mixture of metals or metals and other elements.

• Alloys are made to change the properties of the metal e.g.to make them harder, more pleasing on the eye or to make them more resistant to corrosion.

• Examples are: brass (Cu + Zn), gold (Au + Cu) ( the greater the proportion of Cu the lower the no.of carats), stainless steel (Fe, Ni and Cr)

Metal Ores

• Most metals are found combined with other elements such as, oxygen and sulphur in the earths crust. These are called Metal Ores.

• Only gold, silver and platinum are found uncombined.

• As a result metals must be mined and then separated from their ores by metal extraction

Extraction of Metals from their Ores

• Ores of metals high up in the electrochemical series contain stronger bonds and therefore require more sophisticated and expensive methods of extraction

• Metals low down in the Electrochemical Series form weak bonds with other elements. As a result ores of these metals can broken up easily to obtain the metal.

Electrochemical Series

Can be broken by heat alone

Must be electrolysed to release metal from ore

PlatinumPlatinumGoldGoldSilverSilverMercuryMercury

PotassiumPotassiumSodiumSodiumCalciumCalciumMagnesiumMagnesiumAluminiumAluminium

HYDROGENHYDROGENCopperCopper

ZincZinc

LeadLeadTinTinIronIron

Separated from ore by heating with CHARCOAL, thus releasing

CARBON DIOXIDE.