1. Journal #11 How do you find the average age of the students in this classroom?

2. Current Atomic Model

3. Subatomic Particles ChargeMassLocation Proton + 1 amu (1/12 of a carbon atom) Nucleus Neutronnone1 amuNucleus Electron - Almost 0 amu Outside nucleus In motion

4. Isotopes Distinguishing Atoms

5. What makes an atom unique? Number of protons Number of neutrons Number of electrons

6. The Atom Almost every atom is neutral, a balance of positive & negative charges. FYI: If the nucleus was the size of a pea it would have a mass 250 tons. If the nucleus was the size of a marble, the atom would be the size of a football stadium.

7. atomic number = # of p+ & e- top number # electrons = # protons (in a neutral atom) This number never changes If it did you would make a different element 12.0107

8. mass number = # protons + # neutrons This is NOT on the periodic table! You round the atomic mass to get the mass number of the most common isotope. 12.0107

9. Try some PbAg Na C How many protons, neutrons & electrons do each of the elements have? Use the periodic table in the back of your book: p+= 82 e-= 82 n= 207- 82= 125 p+= 11 e-= 11 n= 23- 11= 12 p+= 6 e-= 6 n= 12- 6= 6 p+= 47 e-= 47 n= 108- 47= 61

10. Stop and practice Packet page 3

11. Isotopes Different versions of an atom # protons is the same – Atomic number is the same # neutrons is different – Mass number is different

12. Chemical Properties of Isotopes Chemically, all isotopes are the same since they all have the same number of electrons. Electrons determine the chemical properties of an element.

13. Designating Isotopes Mass # Symbol 14 C Atomic #6 --------------------------------------------- Hyphen notation: Name – mass #carbon-14 Nuclear symbol:

14. Practice How many protons, electrons and neutrons make up an atom of bromine-80? – 35 protons, 35 electrons, 45 neutrons Write the nuclear symbol for carbon-13 – 13 6 C Write the hyphen notation for the isotope with 15 electrons and 15 neutrons. – Phosphorus-30

15. Try Some + worksheet Atomic # (p+/e-) Mass # (p+ + n) # p+# nsymbol 910 1415 4725 5525

16. Check Atomic #Mass ## p+# nsymbol 919910F 14291415Si 22472225Ti 25552530Mn

17. Stop and practice Do packet pages 9 & 10

18. % abundance Most elements occur as mixtures of isotopes. The % of each isotope that occurs for each element is nearly always the same, no matter where the element is found. The percentage at which each element (ISOTOPE) occurs in nature is called the isotope’s % abundance.

19. Why atomic mass is a decimal Average atomic mass is the weighted average mass of atoms in a naturally occurring setting To calculate (Isotope mass x % abundance) + (Isotope mass x % abundance) = average atomic mass

20. Calculating average atomic mass In order to calculate the average atomic mass, you need to know three things 1.The number of isotopes 2.The mass of each isotope 3.The natural % abundance of each isotope

21. Marble Example : You have 100 marbles; 60 black marbles (5g each), 40 red marbles (8 g each). 1) Find the % abundance of each marble isotope? Marble type x 100 = % abundance Total marbles 60 black marbles x 100= 60% black marbles 100 marbles 40 red marbles x 100= 40 % red marbles 100 marbles

22. 2) What is the average mass of each marble? (Isotope mass x % abundance) + (Isotope mass x % abundance) = average atomic mass (5 g x 60% black marbles) 3.0g + (4g x 40% red marbles) 1.6 g = average atomic mass 4.6 g FYI: 60%= 60 /100=0.60

23. Atomic Mass of Chlorine Element% abundanceMass Chlorine -35 75.77% (divide by 100) 34.969 Chlorine -37 24.23% (divide by 100) 36.966 Atomic Mass

24. Atomic Mass of Chlorine Element% abundanceMass (amu) Chlorine -3575.77% x34.969= 26.496 Chlorine -3724.23% x36.966= 8.957 Atomic Mass 35.453

25. Determine the Element 63 X weighs 62.929601 amu and has a % abundance of 69.15% 65 X weighs 64.927794 amu and has a % abundance of 30.85% Find the average atomic mass and then compare to the periodic table. What is the element?

26. Homework—Due Wednesday 10/7 The M & M Lab Packet page 9 Text pg. 93: 1-7 All QUIZ NEXT CLASS