1. How Electrons Determine Chemical Behavior Day 3

2. Curriculum Big Idea: Chemical bonding occurs as a result of attractive forces between particles. Concept #1: Electrons are found in quantized energy levels within the atom. Concept #2: The electronic structure within atoms is predicted by the Aufbau Principle, the Pauli Exclusion Principle, and Hund’s Rule, giving the atom its most stable arrangement. PA Standard: 3.2.C.A2 “ Compare the electron configurations for the first twenty elements of the periodic table. ”

3. Agenda Opener: How many more electrons does potassium have than Argon? How many less electrons does Oxygen have than Neon? Finish Activity 7: Go over the Investigation and the Chemistry to Go Preview for Thursday and Friday: Ms. Dinger will be presenting research at the National Science Teachers’ Association Conference. Take a look at what you will be working on in class Thursday and Friday. Take notes on subatomic particles and atomic structure. Closure: What is the sublevel to which the last electron is assigned for Magnesium? How many electrons are in this sublevel (Big number, letter, superscript) Take Home Assignement: Read section 4.3 in the Big Red Book

4. Atom: the smallest particle of an element that retains its identity in a chemical reaction

5. Today’s Chemistry Word: The Atomic Nucleus Core of the atom Small Dense Positively charged Composed of protons (+) and neutrons (0)

6. Atomic Number The whole numbers in the blocks of the periodic table The number of protons in one atom of a given element The number of electrons in a NEUTRAL atom of a given element Every element has a different number of protons.

7. Mass Number The total number of protons and neutrons in an atom of a given element Round the atomic masses on the periodic table. # neutrons = mass number – atomic number

8. Protons, Neutrons, Electrons

9. Isotopes of an Element have different numbers of neutrons, so they have different masses. Example: neon-20, neon-21, and neon-22 are three isotopes of neon, a gaseous element used in lighted signs.

10. Isotopes of Hydrogen

11. also called… Hydrogen-1 Hydrogen-2 Hydrogen-3

12. Atomic Mass atomic mass unit (amu): one twelfth of the mass of a carbon-12 atom. Example: helium-4 has about one-third the mass of a carbon-12 atom Example: nickel-60 has about five times the mass of a carbon-12 atom.