Atoms are made up of protons, neutrons, and electrons. Electrons occupy different energy levels around the nucleus. The periodic table arranges elements in order of increasing atomic number and shows patterns in their physical and chemical properties. Elements in the same group have similar properties because they have the same number of valence electrons.

1. Atoms, Electrons & Energy Levels Electrons are the bonds that hold the world together!

2. What’s in an Atom? in surrounding cloud P rotons E lectrons N eutrons Nucleus

3. = No. of = No. of = No. of - From the Periodic Table … http://us.bestgraph.com/gifs/singes-5.html P rotons E lectrons A tomic Number N eutrons C Carbon 6 12 A tomic number M ass number

4. Electron Cloud? http://store.odulo.com/Item.asp?id=220 http://www.fg-a.com/clipart_science_2.shtml 72 6 50 5 32 4 18 3 8 2 2 1 Electron Capacity Energy Level (Principal Quantum Number) H Hydrogen 1 1 He Helium 2 4

5. The periodic table is the most important tool in the chemist’s toolbox!

6. Periodic Table Navigation

7. Periodic Law: When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.

8. The horizontal rows of the periodic table are called PERIODS.

9. 1 2 3 4 5 6 7 Each new period (row) represents an energy level added.

10. The vertical columns of the periodic table are called GROUPS, or FAMILIES. The elements in any group of the periodic table have similar physical and chemical properties!

11. The GROUP provides information about the number of valence electrons. 1 2 13 14 15 16 17 18

12. This Bohr diagram illustrates energy levels and electrons for Phosphorous

21. Atomic radius decreases  Metallic properties decrease  Atomic radius increases  Metallic properties increase 

22. The following periodic trends are embedded within the periodic table: Atomic size (radius), Ionic size (radius), Ionization energy, Electronegativity.

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