science chapter-4 Flashcards
How many elements are known?
116
How many elements are metals
?
89
Number of elements that are Non-metals
18
What are Noble Metals?
Metals which react rarely are called Noble Metals for example gold and silver
What are ores?
The minerals from which metals can be extracted profitably and conveniently are called ores
Define Metallurgy?
It is science of extracting of metals from their respective ores and then refining them
Define Ductility?
The property of metals due to which they can be drawn into wires is called Ductility
Define malleability
The property of metals due to which they can be drawn into sheets is called Malleability
Name physical properties of metals?
Physical state ,Hardness ,Melting or Boiling point ,Malleability ,Ductility ,Conductivity ,Density ,Lustre ,Sonority
Metal + Oxide =
Metaloxide
2Mg + O2 =
2MgO
Metal + Oxygen
Metal oxide + hydrogen !
Metal + Oxygen
Metal oxide + hydrogen !
Metal + dilute salt
Metal salt + hydrogen !
What is Displacement reaction?
Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound.
Cu + FeSo4
No reaction
Mg + CuSO4
MgSo4 + Cu
Define Corrosion
The formation of layer of undesirable compounds on the surface of metals due to exposure to oxygen and moisture is called Corrosion
Bronze is an alloy of
Copper and Tin
How can we prevent corrosion?
Corrosion of metals can be prevented if the metal surface is not allowed to come in contact with moist air
Non-Metals define
Non-metals are those elements that accepts electrons to form negatively charged ions called anions
Write examples of free form of carbon
Graphite diamond and coal
What are Alloys?
Sometimes a metal or non metal is added to metal to improve its properties. The final substance obtained is called an Alloy.
Why is alloy used?
Alloy is used to increase hardness , resistance to corrosion and for changing physical and chemical properties.
