1. Significant Digits & Scientific Notation

2. Agenda • The Importance of Accuracy and Reliability • Significant Digits • Scientific Notation • Activity Time! • What If?? • Team Competition

3. Learning Goals • You will be able to successfully answer questions: • With the appropriate number of significant digits • In scientific notation

4. Measurement Tools

5. Validity & Accuracy • Validity= How “true” something is • Reliability= How “consistent” something is http://ccnmtl.columbia.edu/projects/qmss/images/target.gif

6. Rules for Significant Digits • All digits that are not zero are significant. Example: 16.2 Example: 18,648

7. Rules for Significant Digits • Zeros between non zero digits are significant. Example: 200.5 Example: 100.01

8. Rules for Significant Digits • “Placeholder Zeros” are not significant digits • i.e. Zeros with no numbers to the left Example: 0.02 Example 0.00009

9. Rules for Significant Digits • Zeros to the right of a decimal point are significant if there is a number to the left of it. Example: 16.0 Example: 102.100

10. When Will I Use This? • When answering problems! • When adding or subtracting report the answer with the same number of decimals as the least precise measurement • When multiplying or dividing report answer with the same number of significant digits as the least precise measurement • This may require you to convert your answer to Scientific Notation • Onlyrequired for numbers greater than 10

11. Scientific Notation • Reduce the number to a number below 10 • With the appropriate number of significant digits • Add to on 10X to make number equivalent to your original answer • Moving the decimal 1 place to the left = 101 • Moving the decimal 1 place to the right = 10-1

12. Scientific Notation • Answer the following with three significant digits • Example: 287 • Example: 840,000 • Example: 0.0000683

13. Isotopes Text 1.3: Page 27-31

14. Learning Goals • By the end of this class, the students will be able to: • Differentiate between isotopes of the same element • Determine the relative atomic mass based on isotope mass or isotopic abundance

15. Please Remember! • To complete your Grade 10 Review for FRIDAY! • Will be Formatively Assessed!

16. Dinosaur Bones!

17. Isotopes • Isotopes are like different “species” of an element • They only differ in the number of neutrons in their nucleus

18. The Atom : Pg 11

19. Bohr-Rutherford Model Electron (-) Proton (+) Neutron (o)

20. The Periodic Table: Pg 13

21. Chemical Nature of the Atom • The chemical characteristics or nature of an element is dependent on the ratio between: • Protons (+) and electrons (-)! • This balance results in the charge of the atom • The number of neutrons in an atom can change • This does not alter the chemical nature or characteristics of the atom

22. Hydrogen Isotopes

23. How do you Figure? • Mass Number (A) • Sum number of protons and neutrons • Measured in Atomic mass units (u) • Equivalent to 1/12th of a C-12 atom or… • I u =/ 1.66x10^24g

24. How do you Figure? • Atomic Number (Z) • Number of protons in the atom • So how can we determine the number of neutrons??

25. Determining Number of Protons • If Atomic Number (A) is the number of… • Protons and Neutrons • And Mass Number (Z) is the number of… • Protons Neutrons = A- Z

26. Neutrons = A- Z

27. But wait… • Didn’t we say you can have MORE than 1 number of neutrons in one element? • Wouldn’t that change the weight? • This is why the periodic table also reports the average atomic mass • This number takes into consideration the relative abundance of each individual isotope