Brief introduction to Chemistry For High school

 Introduction to Chemistry

Chemistry divided into three major group :

1. Physical chemistry

2. Organic chemistry

3. Inorganic chemistry

 

The mole, commonly abbreviated mol, is the SI base unit used to measure the amount of a substance. It is the number of representative particles, carbon atoms, in exactly 12 g of pure carbon-12. Through years of experimentation, it has been established that a mole of anything contains 6.022 136 7
1023 representative particles. A representative particle is any kind of particle such as atoms, molecules, formula units, electrons, or ions. The number 6.022 136 7
1023 is called Avogadro’s number in honor of the Italian physicist and lawyer Amedeo Avogadro who, in 1811, determined the volume of one mole of a gas. In this book, Avogadro’s number will be rounded to three significant figures—6.02
1023. If you write out Avogadro’s number, it looks like this. 602 000 000 000 000 000 000 000 Avogadro’s number is an enormous number, as it must be in order to count extremely small particles. As you can imagine, Avogadro’s number would not be convenient for measuring a quantity of marbles. Avogadro’s number of marbles would cover the surface of Earth to a depth of more than six kilometers! But you can see in Figure 11-2 that it is convenient to use the mole to measure substances. One-mole quantities of three substances are shown, each with a different representative particle. The representative particle in a mole of water is the water molecule, the representative particle in a mole of copper is the copper atom, and the representative particle in a mole of sodium chloride is the formula unit.

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