1. 17.1 Atomic Structure *no need to write italicized notes

2. Atoms Determine the properties of all matter (ie. Air/clothes/chair) Atoms of the same element are exactly alike Atoms combine with others to form molecules

3. History of an Atom 4th century B.C. Democritus made atom up. VERY hard to prove. 1808-John Dalton- Atomic Theory 1.) all elements have different atoms 2.) Atoms link to other atom 3. )Molecules or Compounds 1900’s- atoms can be split into other parts…….  Quarks: 3-p & 3-n

4. Composition Protons:+charge Neutrons: = charge Nucleus: Protons + Neutrons (+ charge) Electrons: - charge, moving outside nucleus Atoms overall neutral b/c same # of protons as electrons # Protons determine the element- Atomic #

5. Atom Models 1913- Niel Bohr- electrons move in set orbits= energy levels. Can gain/lose energy to change E. Level 1925-electrons move quickly=electron cloud (orbitals) 4 orbitals= s (sphere), p (dumbbell), d, f (both variety) Valence electron- outermost

7. Periodic Table Periods = 7 Group= 18 4 shapes of atoms: S, P, D, F Lose or gain Neutron= isotope Lose or gain electrons= Ionization Gain Electron- anion Lose Electron- cation

8. 17.2 Masses of Atoms Electrons VERY small-no mass Protons/neutrons = 1.6726 x 10 -24 g=1 amu Atomic #=# of protons=Identifies the element (Average) Atomic Mass=P+N=nucleus # neutrons= mass # - proton # Isotopes