2. COMPOUNDS ARE PURE SUBSTANCES
The pure substances have specific properties and a constant
chemical composition that the mixtures donÂŽt have:
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Air is a mixture ,its composition changes with the humidity or
gases emissions.
Water is a compound, a pure substance,with a constant
composition(2 atoms of hydrogen and 1 of oxigen per mollecule)
So that ,MIXTURES ARE NOT COMPOUNDS.
3. TYPES OF CHEMICAL BONDS.
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According to the type of bond between the elements the
compounds can be classified in types:
IONIC COMPOUNDS: salts, made up by joining ions, cristals
COVALENT COMPOUNDS: the elements are joined by sharing
pairs of electrons,forming mollecules, are gases and liquids.
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METALIC BONDS :are the forces that join the atoms of a metal.
This type of bonds do not form compounds , join the metalic
atoms in a net.
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This structure is formed by positive nuclei together and an
electron cloud sourronding the nuclei, this sea of electrons give
the special properties to the metals.
5. FORCES BETWEEN MOLECULES
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In covalent compounds there are forces that join the molecules.
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A special type of force are hydrogen bonds in water.
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This force makes the water a very special compound with special
properties.
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