Atoms

Atoms

1. An atom is the smallest particle of a chemical element that can exist

2. In order to see atoms, they must be viewed by an electron microscope

3. What makes up an atom

   • All atoms have a nucleus at their center
   • All atoms have one or more electrons
   • All atoms (apart from Hydrogen) have neutrons which can be found in the center of the nucleus
   • All atoms have one or more protons which are found in the center of the nucleus

4. Certain atoms have certain charges. The charge of an atom is determined by its number of electrons and protons

   • Protons have a positive charge
   • Electrons have a negative charge
   • Neutrons have no charge

5. The number of protons in an atom determines its atomic number

6. To calculate an atom's atomic mass you must add its amount of neutrons and protons together

7. Electrons

   • Electrons orbit around the nucleus of an atom. The different energy levels for the electrons are called energy shells. Each shell can hold a limited amount of electrons
     • The first shell can hold two electrons, the second shell can hold eight electrons and the third shell can hold up to eighteen electrons

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