This section is from the book "A Textbook Of Domestic Science", by Matilda G. Campbell. Also available from Amazon: A textbook of domestic science for high schools.
All matter may be classified as organic or inorganic. All organic substances contain carbon. All substances that are formed during the processes of life are organic and, as before stated, great numbers of carbon compounds have been artificially prepared.
Student make a list of eight organic substances. Note. - Student make a list of eight inorganic substances.
In writing the names of elements it is often inconvenient to write the full name, hence the elements are designated by their initial letters, or by those of their Latin names. These abbreviations are called symbols and represent one atom of the element and its combining weight.
1. Oxygen . . . . O
2. Carbon . . . . C
3. Hydrogen. . . . H
4. Nitrogen . . . . N
5. Calcium..... Ca
6. Phosphorus . . . . P
7. Potassium . . . . K
8. Sulphur..... S
9. Sodium .... Na
10. Chlorine ... Cl
11. Magnesium . . Mg
12. Iron..... Fe
13. Iodine.....I
14. Fluorine.....F
15. Silicon.....Si
The combination of symbols which represents the elements found in a molecule of a compound is called a chemical formula. H20 is the formula for a molecule of water, water being composed of two parts by volume of hydrogen and one part of oxygen. CO2 is the formula for carbon dioxide, which is composed of one part by volume of carbon and two parts of oxygen.
When a substance undergoes a chemical change, or when two or more elements or compounds unite chemically, these changes may be represented by means of symbols or formulas in the form of an equation:
H2 + 0 = H20 C + 02 = C02 C + 0 = CO (Carbon Monoxide)
 
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