Today’s Objectives: By the end of today, you should be able to do the following: 1.Define nucleus 2.Recall the parts of an atom 3.Be able to determine the atomic number and atomic mass of an atom 4.Be able to calculate the number of protons, electrons, and neutrons in an atom

Shelf Door Cashier Example Store: (you will have two shelves, refrigerator and freezer)

Focus Assignment: Identify all that you know about these elements from the periodic table in your book: 1.Helium 2.Lithium 3.Boron 4.Sulfur 5.Chlorine Recall: Atomic Number, Group, Period etc.

Do Now – Write a paragraph about what you see. Note what items are in each isle. Note the expressions on the peoples face. How does this compare to your local grocery store?

3.1 – Atomic Structure 1.Atomic Structure 2.The nucleus 4.Particle Charges 3.Electrons 5.Atomic Number 7.Number of Neutrons 6.Atomic Mass

Atomic Structure

E 1.Atomic Structure Made of protons, electrons and neutrons P P N N E Protons Neutron Electrons (2 electrons here)

2. The nucleusMade of protons and neutrons bound tightly together E P P N N E Nucleus

3. Electron location Electrons float around the nucleus in “clouds of probability”

Electron probability clouds: More on this later

4. Particle Charges Proton = +1 Neutron = 0 Electron = -1 E -1 P +1 N0N0 N0N0 E -1 P +1 Therefore, in a neutrally charged atom, the # of electrons = # of protons

Atomic Number and Mass

5. Atomic Number Number of protons in an atom (smaller number of the periodic table) 2 He Helium Atomic Number QUESTION: How many protons does helium have? = 2p +

5. Atomic Number Number of protons in an atom (smaller number of the periodic table) 3 Li Lithium Atomic Number QUESTION: How many protons does lithium have? = 3p +

5. Atomic Number Number of protons in an atom (smaller number of the periodic table) S 16 Sulfur Atomic Number QUESTION: How many protons does sulfur have? = 16p +

6. Atomic MassAmount of protons and neutrons in an atom - average of isotopes (larger number on the periodic table) 2 He Helium QUESTION: What is the atomic mass of Helium? = 4.003

6. Atomic MassAmount of protons and neutrons in an atom (larger number on the periodic table) Li 3 Lithium QUESTION: What is the atomic mass of Helium? = 6.941

7.Number of Neutrons Atomic Mass – Atomic Number = # of Neutrons 24 Mg Mg Mg Protons 12 Neutrons 12 Protons 13 Neutrons 12 Protons 14 Neutrons

7.Number of Neutrons Atomic Mass – Atomic Number = # of Neutrons If no isotope is given, round for the atomic mass 2 He Helium 4 Atomic Mass = 4 Atomic # = n 0

7.Number of Neutrons Atomic Mass – Atomic Number = # of Neutrons Note: We round for the atomic mass 3 Li Lithium 7 Atomic Mass = 7 Atomic # = n 0

Q u e s t i o n s ?

3.1 – Atomic Structure 1.Atomic Structure Made of protons, electrons and neutrons (same amount of electrons and protons.) 2.The nucleus 4.Particle Charges 3.Electrons 5.Atomic Number 7.Number of Neutrons 6.Atomic Mass Made of protons and neutrons bound tightly together Float around the nucleus in clouds Proton = +1, Neutron = 0, Electron = -1 Number of protons in an atom (top number of the periodic table) Amount of protons and neutrons in an atom (bottom number on the periodic table) Atomic Mass – Atomic Number = # of Neutrons

E 1.Atomic Structure Made of protons, electrons and neutrons P P N E P N N N E E