What Is The Difference Between Metals,non-metals, And Metalloids?

Metals are the chemical elements which have the ability to lose electrons to form positive ions. They form metallic bond with metals and ionic bond with non-metals. In metallic bond positive ions are surrounded by electrons and no electron is present in the outer most shell of an atom in metallic bond. Metals are good conductors of heat and electricity. They are shiny, malleable and ductile.

Non-metals are poor conductor of heat and electricity. They are dull, brittle and unmalleable. They have high electronegative and has the ability to gain electrons to form negative ions.

Metalloids are intermediate between metals and nonmetals. They have both the properties of metals and non-metals. They behave as semiconductors and are unmalleable.

There are few differences between metals and non-metals. Firstly, metals are shiny and non-metals are not shiny and they do not have luster. Secondly, metals are malleable and flexible while non-metals are hard and brittle. Thirdly, metals are good conductors of energy like electricity and heat but non-metals are non-conductors and they cannot transfer energy in normal conditions. Fourthly, metals are basic in nature and they form  basic solutions while non-metals are acidic in nature and they form acidic solutions.

Chemical Properties
Metals

•Usually have 1-3 electrons in their outer shell.
•Lose their valence electrons easily.
•Form oxides that are basic.
•Are good reducing agents.
•Have lower electronegativities.
Nonmetals

•Usually have 4-8 electrons in their outer shell.
•Gain or share valence electrons easily.
•Form oxides that are acidic.
•Are good oxidizing agents.
•Have higher electronegativities.

Physical Properties
Metals

•Good electrical conductors and heat conductors.
•Malleable - can be beaten into thin sheets.
•Ductile - can be stretched into wire.
•Possess metallic luster.
•Opaque as thin sheet.
•Solid at room temperature (except Hg).
Nonmetals

•Poor conductors of heat and electricity.
•Brittle - if a solid.
•Nonductile.
•Do not possess metallic luster.
•Transparent as a thin sheet.
•Solids, liquids or gases at room temperature.

     Metals have shiny surfaces and are opaque to light. Also, they aregood conductors of heat and electricity
Some metals and mixtures of metals are strong and do  not rust.Other metals are pounded and pressed
into different shapes or stretched thinly, without breaking.


     Nonmetals have shiny or dull surfaces, may be translucent to light, and are good insulators of heat and
electricity.

(ALL STRAIGHT FROM MY SKOOL TEXTBOOK!)

Metalloids are the materials which are made up of both metals and non-metals and are just like alloys(I think :P).
Non-metals are not reactive, have low boiling and melting points, are non-ductile,non-sonorous and are poor conductor of heat and electricity while metals have the opposite properties of non-metals.

Hope this helps :)