1. T HE A TOM AND THE P ERIODIC T ABLE Science 10

2. Everything that is living is made of cells Cells are made up of molecules Molecules are made up of elements Elements are made up of ATOMS An ATOM is the smallest basic unit of matter

3. The atom contains THREE subatomic particles:  Neutrons  Electrons  Protons

4. The neutrons and protons are contained in the nucleus. They account for the majority of mass of the atom and take up the smallest amount of space. The proton has a positive charge whereas the neutron is neutral.

5. The electron has a negative charge and it is found orbiting around the nucleus in clouds. Only 2 electrons are ever found in the first cloud, 8 in the second and 8 in the third.

6. Using the periodic table you can determine how many protons, neutrons and electrons each atom has. The atomic number represents the number of protons and electrons in a neutral atom. The atomic mass minus the atomic number represents the number of neutrons found in an atom. The atomic mass represents the number of protons and neutrons

7. The atomic number is also known as Z The atomic mass is also known as A The neutron number is known as N Hence A = Z + N

8. The periodic table is organized so that all the elements with similar properties and number of electrons in the outer cloud line up. The table is organized to help us explain and predict chemical and physical properties of elements.

9. Generally metals are arranged on the left side and nonmetals are arranged on the right side An exception is hydrogen, which is located at the top left corner, it behaves mostly as a nonmetal.

10. C HEMICAL F AMILIES Elements may be grouped into families. These are groups of elements in the same vertical column. They tend to have similar chemical and physical properties