3. Phet Simulation of Structure of the Atom Link to Phet build an atom As you watch this simulation try to answer the following questions: 1) What are the basic particles that makeup the atom? 2) Where are they located in the atom? 3) What are the charges of each particle? 4) What are the relative masses of each particle?

4. Atoms are made of Protons Neutrons Electrons ↓ ↓ ↓ Nucleus Nucleus Outside nucleus +1 0 -1 1 amu ≈ 1 amu 0 (amu = atomic mass unit =1.66 x 10- 24 g) ↓ ↓ ↓ ATOMIC # ISOTOPE IONS (chemical identity of atoms) HW 1-7, #1 AND 2, p. 28

5. HW 1-7, #1

6. HW 1-7, #2 2A) 5 protons = 5(+1) = +5 6 neutrons = 6(0) = 0 5 electrons = (5)(-1) = -5 Since # protons = # electrons overall charge = 0. 2B) # protons = # electrons overall charge = 0 2C) +5 - 8 = -3 2D) +5 - 3 = -2

7. IF ALL ATOMS ARE MADE UP OF THE SAME 3 PARTICLES WHAT MAKES ONE ATOM DIFFERENT FROM ANOTHER? Helium, element #2 Lithium, Element #3 Hydrogen, element #1 Link to Phet build an atom

8. HW 1-7, #3 Helium, element #2 Lithium, Element #3 Hydrogen, element #1 Atomic # = number of protons; determines chemical identity of an element

9. ATOMIC MASS Mass of 3 particles that make up atom: Proton = 1 amu, Neutron = 1 amu, electron = 0 Total Mass of Atom is called ATOMIC MASS Atomic # - number of protons; determines chemical identity of an element ATOMIC MASS = # of protons + # of neutrons BACK TO NOTES, p. 7

10. HOW TO DETERMINE # OF NEUTRONS? # of neutrons = atomic mass(p+n) – atomic # (p) 6 (p + n) - 3 (p) = 3 neutrons 7 (p + n) - 3 (p) = 4 neutrons 8 (p + n) - 3 (p) = 5 neutrons

11. Phet Simulation Link to Phet build an atom As you watch the Phet simulation consider the following: 1) What is an ion? 2) How are + or – ions formed? 3) What is the relationship between the # of protons and electrons for neutral, + or – ions?

12. IONS = CHARGED ATOMS + IONS form when e- are LOST -IONs form when e- are GAINED Ions form when atoms gain or lose ELECTRONS.

13. IONS NEUTRAL ATOM: # PROTONS = # ELECTRONS + ION : # PROTONS > # ELECTRONS - ION: # ELECTRONS > # PROTONS

14. HW 1-7, #4, p. 28 4) How is an ion formed? Ans: C – by either adding electrons to or subtracting electrons from the atom

15. 1-7, #5, p. 29 A) +1 ION NEUTRAL ATOM B) -1 ION C) +2 ION D) -3 ION

16. Notation system for representing atomic number, atomic mass and charge Link to Phet build an atom Questions: Where is the atomic # written? What is the # in the top left corner represent? Where is the charge written?

17. Notation System for Protons, Neutrons, and Electrons Top right hand corner indicates charge (if nothing is written, charge = 0)

18. Example: Determine # of proton, neutrons and electrons 25 +2 Mg 12 Protons: Atomic # (Lower left) = Neutrons: Mass (top left) – atomic # = Electrons: # protons (bottom left) – charge (top right) =

19. Example: Determine # of proton, neutrons and electrons 25 +2 Mg 12 Protons: Atomic # (Lower left) = 12 Neutrons: Mass (top left) – atomic # = Electrons: # protons (bottom left) – charge (top right) =

20. Example: Determine # of proton, neutrons and electrons 25 +2 Mg 12 Protons: Atomic # (Lower left) = 12 Neutrons: Mass (top left) – atomic # = 13 Electrons: # protons (bottom left) – charge (top right) =

21. Example: Determine # of proton, neutrons and electrons 25 +2 Mg 12 Protons: Atomic # (Lower left) = 12 Neutrons: Mass (top left) – atomic # = 13 Electrons: # protons (bottom left) – charge (top right) = 12 – (+2) = 10 electrons

22. Phet Simulation Game Review Mode Link to Phet build an atom You can use game mode in this program for extra review in determining protons, neutrons and electrons.

23. Second shorthand notation for neutral atoms He-4 = All Helium atoms have 2 protons; thus if the symbol and mass is given for a neutral atom, # of protons and electrons are known. HW 1-7, #6,7,8, p. 29.

24. HW 1-7, #6: Determine the # of protons, neutrons and electrons. 11 27 +3 14 -3 B Al N 5 13 7 P: P: P: N: N: N: E: E: E: 5 6 5 13 14 10 7 7

25. HW 1-7, # 7 7) An atom has an atomic # of 9 and an atomic mass of 19. A) Chemical Identity: B) # of protons: # of neutrons: Element #9 = Fluorine = 9 19 – 9 = 10

26. HW 1-7, #8: Write notation in vertical format and then determine # of proton, neutrons and electrons C-12 C-13C-14 All atoms are neutral with 6 electrons

27. What is an isotope? Study the picture below of the showing 3 isotopes of Lithium. What is alike and what is different in each picture? Alike: All Lithium atoms have the same atomic # (3), meaning they all have 3 protons (and 3 electrons) Different Lithium atoms have different masses due to different #’s of neutrons in the nucleus.

28. Isotopes - atoms with the same atomic NUMBER with different atomic MASSES. Isotopes have the same # of PROTONS but a different number of NEUTRONS. 3 ISOTOPES OF HYDROGEN 2 ISOTOPES OF HELIUM 2 ISOTOPES OF LITHIUM NOTES, p. 8

29. Isotopes have different masses due to different number of neutrons ISOTOPES ATOMS OF THE SAME ELEMENT WITH DIFFERENT MASSES

30. SUMMARY: IONS vs ISOTOPES ISOTOPES - Chemically same, different mass: Same # of PROTONS, different # of NEUTRONS IONS: Charged atoms: Same # of PROTONS, different # of ELECTRONS - ION + ION

31. HW 1-7, #9, p. 30 8 8 8 20 18 8 9 10 20 21 20 i and iii; ii and iv

32. HW 1-7, #10 Atom X, atomic # = 9; atomic mass = 19, e - = 10 Atom Y, atomic # = 10; atomic mass = 19, e - = 10 A)Is X an ion? B)Is Y an ion? C)Are X and Y isotopes? Yes; -1 ion; 9 + protons and 10 - electrons No; 10 protons and 10 electrons NO: Different # of protons, NOT same element (although mass is same).

33. HW 1-7, #11: Thought Question The mass of boron on the periodic table is listed as 10.8 amu, although there are no atoms of boron that actually weigh 10.8 amu. Where does the number 10.8 come from? Hint #1: Boron has two isotopes, B-10 and B- 11. How would you calculate the average of 10 and 11? Hint #2: How would you calculate the average of 10,10,11,11,11,11,11,11,11,11?

34. Link to Isotopes Select mix isotopes and B to determine answer to our question.

35. Isotopes of Elements in Nature A sample of the atoms of a naturally occurring element will contain a mixture of the different isotopes of that element. Different Isotopes are almost never present in equal amounts Notes, p. 9

36. Average Atomic Mass on the Periodic Table The atomic mass of an element given on the periodic table represents the weighted average of all of the isotopes of the element, taking into account the relative abundance of each isotope.

37. Note: Average mass reflects relative abundance of different isotopes

38. HW 1-7, #12, p. 30 The average mass of a carbon atom is 12.011. Assuming you could pick up one carbon atom, what is the chance that you would randomly get one with a mass of 12.011? A) 0% B) 0.011% C) about 12% D) 12.011% E) greater than 50% F) none of the above. Explain your answer.

39. HW 1-7, #12, p. 30 The average mass of a carbon atom is 12.011. Assuming you could pick up one carbon atom, what is the chance that you would randomly get one with a mass of 12.011? A) 0% B) 0.011% C) about 12% D) 12.011% E) greater than 50% F) none of the above. Explain your answer.