Chemistry
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Free online chemistry lesson for elementary school, middle school and high school.
Atoms and molecules
Atoms
All matters around us (including molecules) consist of microscopic particles called atoms.
There are different kinds of atoms (more than a hundred) that constitute all existing materials.
Each atom is represented by a symbol which begins with a capital letter, sometimes followed by a lowercase letter.
(The first letter often corresponds to the first letter)
Examples to remember:
hydrogen H
oxygen O
carbon C
nitrogen N
iron Fe
sulfur S
chlorine Cl
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