Metals and non-metals||class 10 science lesson 3 notes

 Elements are classified as metals and non-metals. 

Metals are mostly solids, lustrous, have high density, good conductor of heat and electricity, malleable, ductile and tenacious. 

Mercury is a liquid metal. 

Metals lose electrons to form cations. 

Non-metals usually have properties contrary to metals. They usually form acidic oxides. 

Metals activity series

K>Na>Ca>Mg>Al>Zn>Fe>Pb>[H]>Cu>Hg>Ag>Pt>Au.

1) metals below hydrogen cannot displace hydrogen from acids. 

2) metals above hydrogen can displace it from dilute acids. 

3) The higher the position, the more active is the metals. 

Minerals from which metals may be extracted economically are called ores. 

Heating of ore in the presence of air is called roasting. 

Heating of ore in the absence of air is called calcination. 

The process of reducing the roasted ore is called smelting. 

Refining of metals can be carried by distillation, Liquation, oxidation or by electrolytes method. 

An alloy is a homogeneous mixture of one or more metals Or non-metals. 

The surface of some metals such as iron is corroded when they are exposed to moist air for a long period of time. This phenomenon is called corrosion. 

The process of coating iron articles by zinc is known as galvanisation. This is an important method to prevent it from rusting. 

The elements or compounds in the form of which metal occur naturally in the earths crust are called minerals. 

Those minerals from which metals can be profitably extracted are called ores. 

The various impurities like sand, dust, rocky particles that are associated with the ore are called gangue. Gangue is also known as matrix.