1. Tuesday!!!!! 11/1/11 Bell Ringer 1)Get out your Ch. 5 book pages and your notes we started. Schedule 1.Bell Ringer 2.CH. 5 Notes 3.Flame Test Pre-lab HOMEWORK: Print Ch. 5 Notes PAP Chemistry Teachers open the door, but you must enter by yourself. I CAN……solve chemistry problems by being an independent, creative thinker.

2. Dalton Proposed model for atom Dalton’s Atomic Theory – Elements composed of atoms – Atoms of same elements are alike in mass and size*** – Atoms of different elements have different mass and size – Chemical compounds are formed by the union of two or more atoms of the different elements – Atoms combine to form compounds in simple numeric ratios – Atoms of two elements may combine in different ratios to form more than one compound Modifications to Dalton’s original theory: – Atoms are composed of subatomic particles – ***Not all atoms of same element have the same mass – Under certain circumstances, atoms can decompose

3. Use of Models Models are used to explain behavior Dalton’s Atomic Model: – Explains behavior of atoms, compounds and molecules Modifications made when new information arises

4. Law of Definite Composition Compounds contain two or more elements chemically combined in definite proportions by mass Water is always a 1 : 2 ratio, oxygen to hydrogen Hydrogen peroxide is always a 2 : 2 ratio, oxygen to hydrogen

5. Law of Multiple Proportions Atoms of two or more elements may combine in different ratios to produce more than one compound CuClCuCl 2 CH 4 C 8 H 18

6. Significance of the two Laws…why are they so important??? Composition of a substance will ALWAYS be the same Composition of different compounds formed from the same elements will be unique

7. Law v. Model Law – Summary of observed behavior – Remain constant Model (theory) – Attempt to explain the observed behavior – Can be modified

8. Electric Charge Positive Negative Unlike charges attract Like charges repel Charge may transfer form one object to another: induction or contact – Induction: influence of a charged object, NOT BY CONTACT

9. Force, charge and distance F = kq 1 q 2 r 2

10. Ions ( Faraday and Arrhenius) Positive = cations Negative = anions Gain or transfer of electrons (Stoney / Thomson)

11. Subatomic Particles Electron (Thomson) e - – Negative charge – Mass 9.11 x 10 -28 g Proton (Goldstein, Thomson) p + – 1.637 x10 -24 g – Positive charge Neutron (Chadwick) n° – Neutral charge – 1.675 x10 -24 g

12. Rutherford and the Nucleus of the Atom Gold Foil Experiment Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed. Bottom: Observed results: a small portion of the particles were deflected, indicating a small, concentrated positive charge. Note that the image is not to scale; in reality the nucleus is vastly smaller than the electron shell.

13. Atomic Arrangement What makes an atom neutral? Same number of protons and electrons

14. What do the numbers mean? Atomic # = # p + Whole number increasing from left to right on the periodic table # p + = # e - Mass number = n° + p +

15. Isotopes Atom with same atomic number and different numbers of neutrons in nucleus of atom

16. Isotopes Most elements occur in nature as mixtures of isotopes Not all are stable Radioactive isotopes Decompose

17. Atomic Mass Atomic mass or atomic weight Measured in atomic mass units or amu Atomic mass is average relative mass of all naturally occurring isotopes of that element The atomic mass of an element is compared to the atomic mass of carbon-12 (12.00 amu)