The document defines key atomic terms like atom, nucleus, protons, neutrons, and electron cloud. It explains that atoms are the smallest unit of an element, with a nucleus at the center containing protons and neutrons. The number of protons determines the element, while the number of neutrons is calculated using atomic mass and number. Electrons orbit the nucleus and equal the number of protons. Elements are arranged on the periodic table by period and group based on atomic structure and valence electrons. Examples of hydrogen, helium, lithium, fluorine and argon are given showing their atomic makeup.

3. The Atom

4. The Atom

5. Protons Neutrons Nucleus

8. The Atom

11. Periodic Table Periods go across on the periodic table Periods have the same number of “shells” 1 2 3 4 5 6 7

12. Periodic Table Groups go down on the periodic table Elements in the same group, have the same number of valence electrons 1 2 3 4 5 6 8 7

13. Let’s look at a few elements… Hydrogen 1= Proton 1= electron

14. Let’s look at a few elements… Helium 2=protons 2=neutrons 2=electrons

15. Let’s look at a few elements… Lithium 3=protons 4=neutrons 3=electrons

16. Let’s look at a few elements… Fluorine 9=protons 10=neutrons 9=electrons

17. Let’s look at a few elements… Argon 18=protons 22=neutrons 18=electrons