2. Law of Conservation of Mass

3. Law of Definite Proportions

4. Law of Multiple Proportions

5. Atom

6. Thomson’s Cathode-Ray Tube Experiment

7. Millikan’s Oil Drop Experiment

8. Rutherford’s Gold Foil Experiment

9. Periodic Table of the Elements

10. Atomic Number (Z) - the atomic number is unique for each element - provides the number of protons that an element has 6 C Carbon 12.0107 - IF the element is neutral, it also provides the number of electrons Atomic # Atomic symbol

11. Mass Number - the mass number is the number of protons and neutrons in a particular element 6 C Carbon 12.0107 - To find the number of neutrons subtract the number of protons (atomic number) from the mass number. Mass Number - the atomic mass of the element in amu (atomic mass unit)

12. 6 C Carbon 12.0107 26 Fe Iron 55.845 36 Kr Krypton 83.798 Examples Find the number of protons, electrons, and neutron in the following: Protons: Electrons: Neutrons:

13. Ions - elements or group of elements that have gained or lost electrons. - if an element loses electrons it is a positive ion or cation. - if an element gains electrons it is a negative ion or an anion. Examples: sodium (Na) p - e - n - oxygen (O) p - e - n - sodium ion (Na + ) p - e - n - oxygen ion (O 2- ) p - e - n -

14. Isotopes - atoms of the same element with different masses. - mass numbers will be different. - since mass #’s are different, the number of neutrons are not the same. Some isotopes have unique names, some do not. H-1 (hydrogen) H-2 (deuterium) H-3 (tritium) C-12 (carbon 12) C-13 (carbon 13) C-14 (carbon 14) Examples: carbon-12 carbon-14p - e - n -

15. Average Atomic Mass - weighted average of atomic masses of naturally occurring isotopes of an element. Example: Copper copper-63 – 62.92959869.17% of all copper copper-65 – 64.92779330.83% of all copper What is the weighted atomic mass of copper? 63.546 amu

16. Average Atomic Mass

17. Avogadro’s Number - the number of particles in exactly one mole of a pure substance. - 6.022 x 10 23 particles (atoms or molecules) The Mole (mol) - the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon-12. - the mole is a counting unit Molar Mass - mass of one mole of a pure substance - numerically it is equal to the atomic mass of the element or compound. - the unit used is g/mol. - when using molar mass, use 4 significant figures!

18. The Mole

19. Avogadro’s Number

20. Molar Conversions - molar mass and Avogadro’s number can be used as conversion factors to convert from one unit to another 1 mol = 6.022 x 10 23 atoms/molecules 1 mol = molar mass of = any element or compound moles → grams grams → moles moles → atoms atoms → moles atoms → grams grams → atoms There are six conversions: