Classification and Properties Flashcards
What were the first metals to be found and used? Why?
Copper, silver, and gold were the first metals to be found and used as they are at the bottom of the activity series and could be easily extracted.
What is an alloy? Why are alloys made?
An alloy is a combination of two or more metals in a definite proportion to modify the properties of a metal. Alloys modify properties of metals like hardening soft metal by combining them with hard metals.
What is the difference between malleability and ductility?
Malleability is the metallic property to be able to withstand hammering and be beaten into sheets. Ductility is the metallic property to be drawn into wires,
What are metalloids? Give two examples.
Metalloids are substances that have metal as well as non-metal properties. Two examples are boron and germanium.
What is the upper surface of the Earth’s crust made of?
Sand and silicates.
What are the most abundant metals and non-metals in the Earth’s crust?
Metals - Aluminum and iron
Non-metals - Oxygen
What happens to iron when it is exposed to air for long?
When it is exposed to air for long, iron combines with oxygen and forms a reddish-brown coating on the surface called rust.
Why is iron more reactive than gold?
As even when gold is exposed to air it does not combine with any other element and remains in a free state whereas iron combines with oxygen to form iron oxide.
Why is pure gold not used for jewellery?
Pure gold is a soft metal that can easily be deformed and is hence, alloyed with copper and used in jewellery.
State the metallic and non-metallic properties of antimony.
Metal - becomes a good conductor of electricity when alloyed with boron.
Non-metal - bad conductor of electricity at ordinary temperatures.
What is an amphoteric metal or metal oxide?
An amphoteric metal or metal oxide has the ability to act as a base or an acid. Aluminum oxide can react with an acid and a base and is hence an amphoteric substance.
Why do certain metals exist in a combined state?
Certain metals exist in a combined state because of their high reactivity.
Where are metal sulphides found? Why?
Metal sulphides are usually found in rocks as they are insoluble in water.
Where are metal halides found?
In oceans and lakes as they are soluble in rainwater and are
carried by streams and rivers into oceans.
