1. Protons & Electrons Week of 9-10-12

2. Modeling Electrons Clouds Objective Today: Use models and diagrams to learn how to fill the area of the atom called the electron cloud. Electron Cloud Represents the area around the nucleus Electrons move around like bees around a beehive It is NOT unorganized – there are patterns!

3. Energy Levels Electrons are usually found in a “layered area” of the electron cloud Electrons fill up the electron cloud in a specific order Think of filling up cups and needing more cups once your first cups are full The layer CLOSEST to the nucleus fills up first It’s the smallest layer 1 st energy level

4. Diagram of Energy Levels Look at the diagram of energy levels given to your table Only the 1 st four energy levels are shown Each circle represents a spot where an electron can fill I numbered them in the order in which we’ll fill them up How many electrons are needed to fill up the first energy level? How many electrons are needed to fill up the second energy level?

5. Today’s Lab Each Student Pair Needs: 22 Navy Beans (neutrons) 20 Black Beans (protons)Take only what you need from 20 Lentils (electrons)the cups 1 Red Colored Pencil 1 Atomic structure handout (with electron spaces numbered) 1 Periodic Table Follow along at your desk while Mrs. Szymanski models what you need to do.

6. Charged Atoms When an atom is not neutral

7. Review: Neutral Atoms In neutral atoms: The amount of protons is the same as the amount of electrons Example: if an atom has 7 protons, it will also have 7 electrons

8. Valence Electrons An atom is MOST STABLE if its outer most energy level is full Most cases, its 8 electrons Exception: Helium…it has only 2 electrons in its only energy level. Because helium’s valence is full with only 2 electrons, it is considered most stable compared to other atoms. Octet Rule: Atoms usually combine in a way that leaves 8 electrons in its valence shell

9. Charged Atoms = Ions Atoms combine in ways that fill energy levels with electrons. When electrons are donated or accepted, the proton number is no longer equal to the electron number The proton number will NEVER change. It tells you the atomic number Only the electron amount will change depending on the atom

10. Positive & Negative Atoms Positively charged ions: has more protons than electrons Example: Na 1+ Notice how the + can tell you that there are more protons. Negatively charged ions: has more electrons than protons Example: Cl 1- Notice how the – can tell you that there are more electrons