1 / 31

Quantitative Chemistry

Quantitative Chemistry. Atomic Number. Tells the number of protons and electrons the element contains. 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. Mass Number.

keefe-cooley
Download Presentation

Quantitative Chemistry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

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

  6. Calculating Atomic Mass Percent(%) abundance of isotopes Mass of each isotope of that element Weighted average = mass isotope1(%) + mass isotope2(%) + … 100100 LecturePLUS Timberlake 7

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

  8. 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? LecturePLUS Timberlake 9

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

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

  11. Assign X and Y values: X = % 10B Y = % 11B 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 LecturePLUS Timberlake 12

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

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

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

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

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

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

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

  19. Sig. Fig. Rule • Non-zero numbers are always significant • Zeros between non-zero numbers are always significant. • All final zeros to the right of the decimal place are significant.

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

  21. 857 950 1800 45.2 45.0 92000.0 3 2 2 3 3 6 What’s the Sig. Fig. • 0.00243 • 505 • 0.0012300 • 3.22X105 • 1200.0060 • 0023 • 3 • 3 • 5 • 3 • 8 • 2

  22. 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.

  23. 15624 17853 19278 17750 17650 24503 276453 15600 17900 19300 17800 17600 24500 276000 Round to 3 sig. fig.

  24. 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.

  25. 1018 exa E 1015 peta P 1012 tera T 109 giga G 106 mega M 103 kilo k 102 hecto h 101 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

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

  27. 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.

  28. Time= second (s) Length= meter (m) Mass= kilogram (kg) Temperature= Kelvin (K) Volume= liter (L) or cubic centimeter (cm3) Density= g/cm3 SI Units

More Related