how many metals and non-metal are known to us ? Give the names of three physics properties of metal
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Answer:
An element is the simplest form of matter that cannot be split into simpler substances or built from simpler substances by any ordinary chemical or physical method. There are 118 elements known to us, out of which 92 are naturally occurring, while the rest have been prepared artificially. Elements are further classified into metals, non-metals, and metalloids based on their properties, which are correlated with their placement in the periodic table .
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Answer:
Physical Properties of Metals
Metals are lustrous, malleable, ductile, good conductors of heat and electricity. Other properties Include:
State: Metals are solids at room temperature with the exception of mercury, which is liquid at room temperature (Gallium is liquid on hot days).
Luster: Metals have the quality of reflecting light from their surface and can be polished e.g., gold, silver and copper.
Malleability: Metals have the ability to withstand hammering and can be made into thin sheets known as foils. For example, a sugar cube sized chunk of gold can be pounded into a thin sheet that will cover a football field.
Ductility: Metals can be drawn into wires. For example, 100 g of silver can be drawn into a thin wire about 200 meters long.
Hardness: All metals are hard except sodium and potassium, which are soft and can be cut with a knife.
Valency: Metals typically have 1 to 3 electrons in the outermost shell of their atoms.
Conduction: Metals are good conductors because they have free electrons. Silver and copper are the two best conductors of heat and electricity. Lead is the poorest conductor of heat. Bismuth, mercury and iron are also poor conductors
Density: Metals have high density and are very heavy. Iridium and osmium have the highest densities whereas lithium has the lowest density.
Melting and Boiling Points: Metals have high melting and boiling points. Tungsten has the highest melting and boiling points whereas mercury has the lowest. Sodium and potassium also have low melting points.