1. Quantitative Chemistry

2. Atomic Number Tells the number of protons and electrons the element contains

3. Atomic Mass The average of all the mass numbers of all the isotopes of that element. The unit is amu, stands for atomic mass units

4. Mass Number The number of protons plus the number of neutrons found in that element

6. Isotope Atoms of the same element with different numbers of neutrons

7. LecturePLUS Timberlake7 Calculating Atomic Mass Percent(%) abundance of isotopes Mass of each isotope of that element Weighted average = mass isotope 1 (%) + mass isotope 2 (%) + … 100 100

8. LecturePLUS Timberlake8 Atomic Mass of Magnesium Isotopes Mass of Isotope Abundance 24 Mg =24.0 amu 78.70% 25 Mg = 25.0 amu 10.13% 26 Mg = 26.0 amu 11.17% Atomic mass (average mass) Mg = 24.3 amu Mg 24.3

9. LecturePLUS Timberlake9 Learning Check AT7 Gallium is a metallic element found in small lasers used in compact disc players. In a sample of gallium, there is 60.2% of gallium-69 (68.9 amu) atoms and 39.8% of gallium-71 (70.9 amu) atoms. What is the atomic mass of gallium ?

10. LecturePLUS Timberlake10 Solution AT7 Ga-69 68.9 amu x 60.2 = 41.5 amu for 69 Ga 100 Ga-71 (%/100) 70.9 amu x 39.8 = 28.2 amu for 71 Ga 100 Atomic mass Ga = 69.7 amu

11. LecturePLUS Timberlake11 Finding An Isotopic Mass A sample of boron consists of 10 B (mass 10.0 amu) and 11 B (mass 11.0 amu). If the average atomic mass of B is 10.8 amu, what is the % abundance of each boron isotope?

12. LecturePLUS Timberlake12 Assign X and Y values: X = % 10 B Y = % 11 B Determine Y in terms of X X + Y = 100 Y = 100 - X Solve for X: X (10.0) + (100 - X )(11.0) = 10.8 100 100 Multiply through by 100 10.0 X + 1100 - 11.0X = 1080

13. LecturePLUS Timberlake13 Collect X terms 10.0 X - 11.0 X = 1080 - 1100 - 1.0 X = -20 X = -20 = 20 % 10 B - 1.0 Y = 100 - X % 11 B = 100 - 20% = 80% 11 B

14. LecturePLUS Timberlake14 Learning Check AT8 Copper has two isotopes 63 Cu (62.9 amu) and 65 Cu (64.9 amu). What is the % abundance of each isotope? (Hint: Check periodic table for atomic mass) 1) 30%2) 70%3) 100%

15. LecturePLUS Timberlake15 Solution AT8 2) 70% Solution 62.9X + 6490 - 64.9X = 6350 -2.0 X = -140 X = 70%

16. Ratio Is the mathematical relationship between two quantities in the form of a fraction or percentage

17. Ratio Analysis is essentially concerned with the calculation of relationships

18. Law of Conservation of Mass States that in any reaction, the same amount of mass must be found on both sides of the equation.

19. Significant Figures When making measurements, it is the size of the measurement needed to be precise.

20. Sig. Fig. Rule 1)Non-zero numbers are always significant 2)Zeros between non-zero numbers are always significant. 3)All final zeros to the right of the decimal place are significant.

21. Sig. Fig. Rule 4)Zeros that act as placeholders are not significant. 5)All numbers in calculations should have same sig. fig. go with the smallest sig. fig. number 6)Counting numbers and defined constants do not change.

22. What’s the Sig. Fig. 857 950 1800 45.2 45.0 92000.0 3 2 2 3 3 6 0.00243 505 0.0012300 3.22X10 5 1200.0060 0023 3 3 5 3 8 2

23. Scientific Notation Expresses numbers as a multiple of two factors-a number between 1 and 10, and 10 raised to a power or exponent; makes it easier to write a really big number or really small number.

24. Round to 3 sig. fig. 15624 17853 19278 17750 17650 24503 276453 15600 17900 19300 17800 17600 24500 276000

25. Rounding Rules If digit after sig # is above 5, then round up If digit after sig # is below 5 then leave as is If digit after sig # is 5 and # after 5 is not zero, then round up If digit after sig # is 5 and # after 5 is zero; if sig # is odd round up and if even then leave as is.

26. 10 18 exa E 10 15 peta P 10 12 tera T 10 9 giga G 10 6 mega M 10 3 kilo k 10 2 hecto h 10 1 deka da 10 -1 deci d 10 -2 centi c 10 -3 milli m 10 -6 micro µ 10 -9 nano n 10 -12 pico p 10 -15 femto f 10 -18 atto a

29. Dimensional Analysis A problem solving method that focuses on the units that are used to describe matter.

30. System International Units (SI Units) Units are a name tag that lets you know what measurement the number is for. The SI Units are the standard units use throughout the world.

31. SI Units Time= second (s) Length= meter (m) Mass= kilogram (kg) Temperature= Kelvin (K) Volume= liter (L) or cubic centimeter (cm 3 ) Density= g/cm 3