The compound is a combination of several elements that are formed through chemical reactions . Compounds have properties that are different from their constituent elements . For example , two atoms of hydrogen with one atom of oxygen can
combine to form a molecule of water ( H2O ) . Hydrogen is a very light gas and flammable , whereas oxygen is the gas
contained in the air that our bodies need for combustion .
It seems clear that the properties of water vary with the nature of hydrogen and oxygen .
Another example is the compound kitchen salt ( NaCl ) . Salt prepared by the elements sodium and chlorine elements . Sodium has a light metallic properties , while chlorine is a toxic gas . The two elements are combined to form a mineral salt that is needed by our bodies . The compound includes a single substance that is composed of several elements with a fixed mass ratio . In nature , there are approximately 10 million compounds . Water ( H2O ) is the most abundant compound in nature .
How compound manner of writing ? Compounds are written in the form of a chemical formula . Its chemical formula is a substance that consists of a collection of symbols of elements with a certain composition . the composition
a number that states the number of constituent atoms ( index numbers ) . For example , a compound made up of atoms of the element sodium ( Na ) and chlorine atoms of the element ( Cl ) . If the index numbers of atoms of each element is
1 and 1 , then the chemical formula of the compound that is formed as follows :
The index number Na = 1 , the index number Cl = 1 ,
So the chemical formula of the compound is NaCl ( Sodium chloride ) . The chemical formula can be a molecular formula and empirical formula . The molecular formula is a chemical formula that states the type and number of atoms
that make up the substance . For example , C2H4 ( Ethene ) , H2O ( water ) . The empirical formula is a chemical formula that states the smallest ratio of the number of atoms forming the compound . For example , the chemical formula C2H4 , the empirical formula of the compound is CH2 . Lonis Joseph Proust ( 1754 ~ 1826 ) a scientist from France
revealed
comparative law fixed or often known as Proust's law , namely : the
weight ratio of the elements making up the compound is fixed . Experiments were conducted Proust was a reaction between hydrogen and oxygen elements to form water ( H2O ) . From the experiments conducted by Proust be concluded that :
1 . Water is composed of oxygen and hydrogen with a mass ratio of oxygen elemental appeal of hydrogen is 8 : 1
2 . Amount of substances before and after the reaction is fixed . If
the ratio between oxygen and hydrogen is not 8 : 1 , then the reaction
contained the remaining elements ( oxygen or hydrogen ) . The law of conservation of mass states that the mass of substances before the reaction and after the reaction is fixed . Perform the following activities !
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