1. Chapter 8 Earth Chemistry Part 2

2. 8.1 – Atomic Number  An atom of a specific element is different from other elements by the number of protons it has  Atomic Number is the number of protons in an atom.  All atoms of any element have exactly the same number of protons

3. 8.1 – Atomic Number  The number of protons also equals the number of electrons in a neutral atom  So, the atomic number tells us how many protons which equals how many electrons  Example: Oxygen’s atomic number is 8  It has 8 protons and 8 electrons

4. 8.1 – Periodic Table  The periodic table is a list of all the known elements in order by their atomic numbers  It is used to classify the elements into groups

5. 8.1 – Mass Number  Each atom has a mass number.  Mass number is the number of protons plus the number of neutrons in the atom  The mass number is not on the periodic table

6. 8.1 – Mass Number  You can use the atomic number and mass number to find the total number of protons, neutrons, and electrons  Mass # - Atomic # = # Neutrons

7. 8.1 – Isotopes  Atoms of the same element but with different numbers of neutrons are called isotopes  The more neutrons an atom has the more mass it has