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Introduction to Chemistry

Introduction to Chemistry. Matter. Measurements in science are handled using the metric system: length - meters volume - liters mass - grams. You can use very large or very small numbers like 5 000 000 g or 0.000 000 005 g. 5 000 000 g or 0.000 000 005 g.

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Introduction to Chemistry

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  1. Introduction to Chemistry

  2. Matter

  3. Measurements in science are handled using the metric system: length - meters volume - liters mass - grams You can use very large or very small numbers like 5 000 000 g or 0.000 000 005 g 5 000 000 g or 0.000 000 005 g You can rewrite them in scientific notation 5 x 10 6 g or 5 x 10 -9 g 5 x 10 6 g or 5 x 10 -9 g Or you can use metric prefixes that represent exponential values of 10 5 Mg (M=106) or 5 ng (n = 10 -9) 5 Mg (M=106) or 5 ng (n = 10 -9)

  4. Prefix Symbol Meaning Exponential Notation Exa E 1,000,000,000,000,000,000 1018 Peta P 1,000,000,000,000,000 1015 Tera T 1,000,000,000,000 1012 Giga G 1,000,000,000 109 Mega M 1,000,000 106 Kilo k 1,000 103 Hecto h 100 102 Deka da 10 101 ----- ---- 1 100 Deci d 0.1 10-1 Centi c 0.01 10-2 Milli m 0.001 10-3 Micro  0.000001 10-6 Nano n 0.000000001 10-9 Pico p 0.000000000001 10-12 Femto f 0.000000000000001 10-15 Atto a 0.000000000000000001 10-18

  5. Scientific Notation Try on your own: 140 000 000 000 34 000 564 878 000 0.000 000 000 000 26 0.000 000 511 1.4 x 10 11 3.4 x 10 4 5.64878 x 10 8 2.6 x 10 -13 5.11 x 10 -7

  6. Scientific Notation A way to simplify very large or very small numbers 9 000 000 000 = 9.0 x 10 9 0.000 000 34 = 3.4 x 10 -7 • Rules • You may only have one digit to the left of the decimal • That digit must be > 1 but < 9 • Count the number of places you have moved the decimal from its original location and make it the exponent in x 10 ? If the decimal is moved left the exponent is + If the decimal is moved right the exponent is -

  7. How much do you remember about significant digits?? Identify the number of sig figs in each of the following numbers. : a.) 0.0023 g b.) 2.40 L c.) 2 centuries d.) 250 inches e.) 432 ft f.) $28.04 Answers: a)2, b.) 3, c) infinite, d) 2, e)3, f) 4

  8. Significant figures are a way to deal with uncertainty in Measurement. • Rules for significant figures: • All nonzero digits are significant • All zeros between non zero digits are significant • Leading zeroes are NOT significant • Trailing zeroes are NOT significant if there is no decimal point in the number. • Exact numbers such as counted numbers or numbers in a Definition like 1 dozen =12 pieces do not have an affect on a Calculation, they are considered to have an infinite number of Significant figures.

  9. Try again: 347 mL 0.0045 g c) 100 oz d) 85.0 mL e) 4075 kg f) 0.0560 m g) 520. g h) 8.000 g 0.302 lb j) 1006 m

  10. Significant Figures in calculations Muliplication and Division Find out how many sig figs are in each number in the problem. 2.36 x 1.631 3 4 Do the math 2.36 x 1.631 = 3.84916 Your answer must now be rounded off to the lowest number of sig figs present in the problem, in this case, 3 Answer 3.85 You can only be as certain as your least certain instrument.

  11. Practice (Rules for multiplication and Division are the same.) 1.) 12.3 x 3.6 x 0.4356 = 2.) 15 ÷ 4.21 = 3.) 3.145 x 103 x 6.1 x 1012 = 4.) 3.18 x 103 x 6.4 x 10-4 = 19.288368 = 19 3.56294537 = 3.6 1.91845 x 1016 = 1.9 x 10 16 2.0352 = 2.0

  12. Addition and Subtraction 1. Line up numbers at decimal point, complete addition of subtraction 2. Where number is rounded depends on the least certain value, meaning the place value closest to the decimal. 12.364 + 121.1 = ? 12.364 121.1 Tenths place value is least certain so round at that place value = 133.5 133.464

  13. This buret is graduated by 0.1 mL increments. Your measurement can be certain to the tenths place value. Even though you can predict a number in the hundredths place value, it may be different depending on who you are. Therefore, it is an uncertain number. Person Reading 1 20.15 mL 2 20.14 mL 3 20.16 mL Since each person has a variance of 0.01 mL, we say the measurement is 20.1X + 0.01 mL

  14. This instrument is called an analytical balance. It reads to 4 places past the decimal point. With uncertainty factored in, we would read this measurement as 89.2863 + 0.0001 g On an instrument this sensitive the last number fluctuates constantly so even though it has a digital readout you may have it reading 2 numbers without settling on either one.

  15. Precision and Accuracy Somewhat organized. All information collected in one location Completely random data. Very organized. All information collected in expected location Precision - Reproducibility for each trial of an experiment Accuracy - Agreement with a known value

  16. Temperature scales in science Metric System - Celsius after the Swede Andres Celsius. He set freezing of H2O as 0°C and boiling at 100 °C then broke up the scale into 100 pieces. Kelvin - Based on research in gas laws done by Lord Kelvin. He found that all gases eventually reach the same temperature if cooled, -273 °C . He set this as O K or Absolute Zero. To convert between Celsius and Kelvin: K = C + 273

  17. Data Studio Download for home: www.pasco.com ID: 5815 License Key: BVCNDPN-ZHIAGOM-ICGGQLS-JAJCFIL

  18. Some important people to know! (Because they discovered the particles in an atom or something about them.)

  19. Democritus First credited with the “idea’ of the atom. Theorized that there were indivisible particles that made up all matter. Idea was negated by Socrates/Aristotle (who was more popular) and was not accepted again until late 1700’s when John Dalton determined that matter is made up of smaller particles.

  20. Dalton

  21. Law of Conservation of Mass

  22. Thomson

  23. J.J. Thomson - Credited with the discovery of electrons. Thompson wanted to discover the makeup of the atom and so did experiments that led him to the discovery that there were negatively charged particles in the atom. Since atom are neutral particles he also guessed that there was some positively charged component to the atom.

  24. Robert Millikan - Determined the charge of an electron.

  25. Rutherford

  26. Ernest Rutherford - Discovered a large mass that was reflecting back electrons in an atom. Named it “nucleus”. Determined that the positive portion of an atom was located in the center.

  27. The pieces of an atom Charge Location Size in relation to Each other Protons Neutrons Electrons Positive Neutral Negative 1 amu 1 amu 1/1879 amu Nucleus Nucleus Electron Cloud

  28. Atomic Number Reading the periodic table 6 C Symbol Name Carbon 12.011 Atomic Mass

  29. Atomic Symbol - An abbreviation of an element’s name. May or may not match the beginning of our language. Carbon - C Sodium- Na from latin Natrium Lead- Pb from latin Plumbum Atomic Number - Tells number of protons and electrons in an atom. Atomic Mass - Sum of protons and neutrons in atom

  30. A shortcut way of writing out this information is 12C 6 Chemical Symbol This gives isotopic mass atomic number

  31. SO3-2 CrO4-2 Na+1 NH4+1 Fe +2 O2-2 Hg2+2 ClO-1 dichromate aluminum lead (IV) potassium bromide selenide cyanide

  32. Density D = m/V Know your volume formulas for 3D shapes V=bh V=lwh V=4/3p r3 V=1/3p r2h The density of osmium is 22.57 g/cm3. If a 1.00 kg rectangular block of osmium has two dimensions of 4.00 cm x 4.00 cm, calculate the third dimension of the block.

  33. An iron cylinder has a density of 7.874 g/cm3. If the cylinder weighs 53.25 g and has a height of 6.0 cm, Find the diameter of the cylinder.

  34. Elements were thought to be limited in number Early version of the periodic table.

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