1. Mrs. Nielsen Chemistry

2. The History of the Periodic Table By 1860, more than 60 elements had been discovered, but scientists had no way of organizing the elements. Dmitri Mendeleev’s first published periodic table A spiral periodic table

3.  Developed by Henry Moseley in 1911  Elements are organized by increasing atomic number  Elements with similar properties occur at regular intervals

4. Rows = “periods”  Properties vary across a period Columns = “groups” or “families”  Similar bonding capabilities  Elements in a compound may be replaced by other elements in the same family.

5. Families of Elements Group 2: Alkaline Earth metals Highly reactive Group 3-12: Transition metals Group 17: Halogens Very reactive, often react with alkali metals Group 18: Noble Gases Unreactive, already “happy” Group 1: Alkali Metals Highly reactive, not found as free elements in nature Why are Br and Hg a different color?

6. Metals (“downstairs”)  good conductors of heat and electricity  malleable  ductile  tensile strength  luster Non-Metals (“upstairs”)  poor conductors of heat and electricity Metalloids (on the stairs)  semi-conductors of heat and electricity

7. Use the white boards with periodic tables to complete the following tasks.  Put a star around the alkali metal that has 3 protons.  Shade in the noble gas that is in the 4 th period.  Circle the halogen that is a liquid at room temperature.  Put a square around the transition metals.  Label the Lanthanide series with an L.  Label the Actinide series with an A.  Draw a triangle around 2 of the metalloids.  Put an “X” through the non–metal in Group 14.  Draw a over the alkaline earth metal with an atomic # of 20.

8. The Periodic Table as a REFERENCE TOOL

9. ATOMIC STRUCTURE An electron is a negatively charged particle that occupies the space around the nucleus. A proton is a positively charged particle found within the nucleus. (Mass = 1 a.m.u.) A neutron is a neutrally charged particle found within the nucleus. (Mass = 1 a.m.u.) Nucleus Helium When # protons = # electrons then the atom is NEUTRAL

10. 29 Cu 63.55 Average Mass = a weighted average based on how common an isotope is. Element Symbol Atomic # = # of protons How do I use the periodic table as a reference tool?

11. Examples: 1) You have 100 marbles. 25 marbles have a mass = 2.0g 75 marbles have a mass = 3.0g 2) There are 2 forms of naturally occurring copper. Copper – 63 (69.17%) = 62.929598 amu Copper – 65 (30.83%) = 64.927793 amu.6917 (62.929598) +.3083 (64.927793) = 63.55 amu.25 (2.0g) +.75 (3.0g) = 2.75 g

12. The mass of an element can be used to determine either the atomic mass or the molar mass. Atomic Mass Molar Mass Units: Atomic mass unit (amu) = the mass of 1 atom of any element. One helium atom has a mass of 4.002 amu Units: grams per mole (g/mol) = the mass of 1 mole of atoms of any element. One mole of sulfur atoms has a mass of 32.066 g/mol

13. Atomic MassFormula MassMolar Mass *Mass of each element*Total mass based from the empirical formula (simplest formula) and ionic compound *Total mass of each element in one mole of a compound Use value in the periodic table Unit is amu Use value in the periodic table, add each element Unit is amu *Use value in the periodic table, add each element Unit is g/mole Example: Ag = 107.87 amu Example: NaCl = 22.99 + 35.45 =58.44 amu *Example CO2 = 12.01 + 2(16.00) =44.01 g/mole * For more example, see Chp. 8.4 pg. 213

14. What do these new units mean? Atomic Mass Units (amu)  1 amu = 1.660504 x 10 -24 g  Carbon – 12 is set as the standard measurement at 12 amu.  Therefore, the atomic mass of any element is found by comparing its mass with Carbon-12. Grams per Mole (g/mol)  How many items are in 1 mole? Yes indeed! There are 6.02 x 10 23 items in 1 mole.

15. The current world population is approximately 7 billion people. If everybody in the world was working together to count one mole of atoms, and each person is counting at a rate of 1 atom/second, it would take over 2.7 MILLION YEARS to count all of the atoms in one mole! Conclusion: 6.02 x 10 23 is a REALLY BIG number!

16. During a chemical reaction, matter cannot be created nor destroyed. Example: Aerobic Respiration C 6 H 12 O 6 + 6 O 2  6 CO 2 + 6 H 2 O Reactants 6 Carbon 12 Hydrogen 18 Oxygen Products 6 Carbon 12 Hydrogen 18 Oxygen =

17. A given compound always contains elements in exactly the same proportion. Examples: Chemical Name Chemical Formula Ratio Sodium Chloride NaCl1 Na: 1 Cl Calcium Fluoride CaF 2 1 Ca: 2 F Iron (III) Oxide Fe 2 O 3 2 Fe : 3 O

19. Dalton’s Atomic Theory Copyright © by McDougal Littell. All rights reserved.19 1. All matter is composed of atoms 2. Atoms cannot be made or destroyed 3. All atoms of the same element are identical 4. Different elements have different types of atoms 5. Chemical reactions occur when atoms are rearranged 6. Compounds are formed from atoms of the constituent elements.

20. JJ Thomson’s Plum Pudding Model Thomson knew atoms were neutral, so there must be a balance of negative and positive particles. Copyright © by McDougal Littell. All rights reserved.20 Dalton’s Model Thomson’s Model

21. Rutherford’s Gold Foil Experiment (1909) ObservationConclusion the vast majority of particles passed straight through the foil a very small percentage of particles were deflected through angles much larger than 90 degrees Copyright © by McDougal Littell. All rights reserved.21 Rutherford’s Model *Atoms are mostly made of open space *massive center with a + charge (the nucleus)

22. Copyright © by McDougal Littell. All rights reserved.22 Bohr’s Planetary Model -- each orbit has more energy the further away from the nucleus --obsolete because it can only apply to hydrogen

23. Copyright © by McDougal Littell. All rights reserved.23 Figure 11.21: The first four principle energy levels in the hydrogen atom.

24. Copyright © by McDougal Littell. All rights reserved.24 Figure 11.8: An excited lithium atom emitting a photon of red light to drop to a lower energy state.