Principles of Chemistry

C1 - Principles of Chemistry

Atom = 3 subatomic particles

• protons (found in nucleus with mass 1)
• neutrons (found in nucleus with mass 1)
• electrons (orbiting the nucleus with mass 1/1840)

Elements are made up of only one type of atom

The atomic number of the element in the periodic table tells us the number of protons and electrons - this is the smaller number.

The number of neutrons = nucleon number - the atomic number

Example:

Gold (Au) - Nucleon number is 197 and atomic number is 79

- 197 - 79 = number of nucleons = 118

- Number of protons and electrons is 79.

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