2. Unit 3 Atomic Theory

3. Atom Smallest particle possessing the properties of an element.

4. Nucleus Dense, positively charged central region that contains protons and neutrons.

5. Protons Positively charged subatomic particles that are found in the nucleus

6. Neutrons Neutral subatomic particles (have no electrical charge) that are found in the nucleus.

7. Electron Cloud Different energy levels surrounding the atom’s nucleus where electrons can be found.

8. Electrons Negatively charged subatomic particles that surround the nucleus.

9. Atomic Number The number of protons in an atom.

10. Atomic Mass The relative average mass of an atom of an element as found in nature. Atomic mass = # of protons + # of neutrons.

11. II: Atomic Particles ParticleMassLocationCharge Proton 1 AMU NucleusPositive Neutron NucleusNeutral Electron 0 AMU Electron cloud Negative

12. Isotopes Atoms of the same element that have a different number of neutrons.

13. Isotopes  Two (2) or more atoms of the same element with a different mass.  Percent (%) abundance: Protium, Deuterium, Tritium 99.985%, 0.015%, 0%

14. Self Check 1.What two subatomic particle are found in the nucleus? A. Neutrons and Electrons B. Protons and Electrons C. Neutrons and Protons D. Neutrons only D. Neutrons only

15. Self Check 2.The atomic number is equal to the _______. A. Number of neutrons in an atom. B. Number of electrons in an atom. C. Number of neutrons plus the number of protons in an atom. D. Number of protons in an atom.

16. Self Check 3.Isotopes are atoms of the same element that have a different number of ______. A. Neutrons B. Protons C. Electrons D. All of the above

17. Self Check 4.The element with an atomic number of 14 is? A. Nitrogen B. Silicon C. Aluminum D. Sulfur

18. Important Number Stuff  Atomic number is equal to the number of protons (and electrons in a neutral atom)  Atomic Mass is the sum of protons and neutrons

19. Examples… Element # protons # neutrons # electrons Ave. Atomic mass Boron56510.811 Sulfur16161632.006 Gold7911879196.96

20. Sample—look at “2_weighted ave.”  Of 100 marbles: –25 have a mass of 2.00g –75 have a mass of 3.00g –What is the average mass?  25% = 0.2575% = 0.75  (0.25 x 2.00) + (3.00 x 0.75) = Ave Mass  0.5 + 2.25 = 2.75

21. Sample with Atoms  Copper 63 amu = 69.17%  Copper 65 amu = 30.83%  Calculate the Average atomic mass

22. Continued…  Copper 63 amu = 69.17  Copper 65 amu = 30.83  Calculate the Average atomic mass  (63 x 0.6917) + (65 x 0.3083)  63.617 AMU –Check on periodic table

23. Ions Electrically charged atoms or groups of atoms. Cations = positively charged Anions = negatively charged

24. I: Models of the atom over time  Democritus: fifth century BC Philosopher –First to describe matter as made of tiny particles  John Dalton: “Billiard ball” theory 1803 –Atom = small solid sphere  In an element = all the same “sphere”  Different elements = different “sphere”  Compounds = different spheres combined in different ratios

25. Continued…  JJ Thompson: 1897 “Plum Pudding” model –Atom = sphere of + and – particles –Discovered the electron = Nobel prize

26. Valence Electrons Electrons found in the outer-most energy level of the electron cloud. Identify patterns using periodic table based on element location

27. Continued  Ernest Rutherford: 1908 –Atom = mostly empty space  + nucleus  - electrons outside  Niels Bohr: 1913 –Electrons traveled in circular orbits

28. Continued…  Electron Cloud Model: 1920’s –Atom = Dense nucleus of + protons and neutral neutrons. –Electrons surround nucleus in “clouds” of different NRG levels. (NRG =Numerical Renormalization Group)

29. Elements on the Periodic Table 1 Hydrogen H 1.008

30. Self Check 5.Draw a picture of what Iron in its neutral state would look like on the periodic table. Hint:

31. Self Check Answers 1. C 2. D 3. A 4. B 5. 26 Iron Fe 55.85

32. III. Molar Conversions III. Molar Conversions

33. A. What is the Mole?  A counting number (like a dozen)  Avogadro’s number (N A )  1 mol = 6  10 23 items A large amount!!!!

34.  1 mole of hockey pucks would equal the mass of the moon! A. What is the Mole?  1 mole of pennies would cover the Earth 1/4 mile deep!  1 mole of basketballs would fill a bag the size of the earth!

35. B. Molar Mass  The mass of 1 mole of an element or compound. Round to nearest whole number (except chlorine)  Atomic weight label: –amu/atom or g/mol  Molecular weight label: –amu/molecule or g/mol

36. B. Molar Mass Examples  carbon  aluminum  zinc 12 g/mol 27 g/mol 65 g/mol

37. B. Molar Mass Examples  water  sodium chloride –H2O–H2O–H2O–H2O –2(1) + 16 = 18 g/mol –NaCl –23 + 35.5 = 58.5 g/mol

38. B. Molar Mass Examples  sodium bicarbonate  sucrose –NaHCO 3 –23 + 1 + 12 + 3(16) = 84 g/mol –C 12 H 22 O 11 –12(12) + 22(1) + 11(16) = 342 g/mol

39. C. Molar Conversions molar mass (g)(g) MASS IN GRAMS MOLES NUMBER OF PARTICLES 6  10 23 (atoms/molecules)

40. C. Molar Conversion Examples  How many moles of carbon are in 26 g of carbon? 26 g C 1 mol C 12 g C = 2.17 mol C

41. C. Molar Conversion Examples  How many molecules are in 2.50 moles of C 12 H 22 O 11 ? 2.50 mol C 12 H 22 O 11 6  10 23 molecules 1 mol = 1.5  10 24 molecules molecules C 12 H 22 O 11 C 12 H 22 O 11

42. C. Molar Conversion Examples  Find the mass of 2.5 moles of NaHCO 3. 2.5 mol NaHCO 3 84 g 84 g 1 mol = 210 g NaHCO 3

43. Patterns on the Periodic Table