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Matter and Measurement: Classification, Units, and Significant Figures

Learn about the classification of matter, SI units of measurement, and significant figures in this chapter. Explore the different types of matter, measurement techniques, and the importance of reporting accurate and precise measurements.

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Matter and Measurement: Classification, Units, and Significant Figures

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  1. Chapter 1 • Matter and Measurement

  2. Matter Pure Substance Mixture Element Compound Homogeneous Heterogeneous Salt water Sandy water Iron Salt, NaCl Classification of matter

  3. Pure substances • Element • Cannot be converted to a simpler form by a chemical reaction. • Example hydrogen and oxygen • Compound • Combination of two or more elements in a definite, reproducible way. • Example water - H2O

  4. Mixtures • A combination of two or more pure substances. • Homogeneous - Uniform composition • Heterogeneous - Non-uniform composition • Which are homogeneous or heterogeneous? • Blood Kool-Aid Air • Gasoline Twinkie Salad Dressing

  5. Lab Techniques Filtration Distillation Chromatography Gas-liquid Chromatography

  6. What process is this called and what is it used for?

  7. Salt remains after all water is boiled off.

  8. Paper Chromatography • Chromatography is a method used to separate mixtures. • There is a mobile phase and a stationary phase. • There are many types of chromatography • TLC • GC • Gel Electrophoresis

  9. Gas-Liquid Chromatography

  10. SI Units • Many different systems for measuring the world around us have developed over the years. • People in the U.S. rely on the English System. • Scientists make use of SI units so that we all are speaking the same measurement language.

  11. Measurement in chemistry • Metric Units One base unit for each type of measurement. Use a prefix to change the size of unit. • Some common base units. • Type NameSymbol • Mass gram g • Length meter m • Volume liter L • Time second s • Energy joule J

  12. Metric prefixes • Changing the prefix alters the size of a unit. Prefix Symbol Factor mega M 106 1 000 000 kilo k 103 1 000 hecto h 102 100 dekada 101 10 base - 100 1 deci d 10-1 0.1 centi c 10-2 0.01 milli m 10-3 0.001 micro µ 10-6 0.000001 nano n 10-9 0.000000001

  13. mg g g kg Example. Metric conversion • How many milligrams are in a kilogram? • 1 kg = 1000 g • 1 g = 1000 mg • 1 kg x 1000 x 1000 • = 1 000 000 mg

  14. Converting units • Factor label method/Dimensional Analysis • Regardless of conversion, keeping track of units makes thing come out right • Must use conversion factors • - The relationship between two units • Canceling out units is a way of checking that your calculation is set up right!

  15. Certain Digits Uncertain Digit Significant figures • Method used to express accuracy and precision. • You can’t report numbers better than the method used to measure them. • 67.2 units = three significant figures

  16. Significant figures • 255 • 25.5 • 2.55 • 0.255 • 0.0255 These numbers All have three significant figures!

  17. Significant figures: Rules for zeros • Leading zeros are notsignificant. 0.421 - three significant figures Leading zero Captive zeros are significant. 4012 - four significant figures Captive zero Trailing zeros are significant when there is a decimal point. 114.20 - five significant figures Trailing zero

  18. Significant figures • In science, all of our numbers are either measured or exact. • Exact - Infinite number of significant figures. • Measured - the tool used will tell you the level of significance. Varies based on the tool. • Example • Ruler with lines at 1/16” intervals. • A balance might be able to measure to the nearest 0.1 grams.

  19. Significant figures:Rules for zeros • Scientific notation - can be used to clearly express significant figures. • A properly written number in scientific notation always has the the proper number of significant figures. 0.00321 = 3.21 x 10-3 Three Significant Figures

  20. Example • 257 mg • \__ 3 significant figures • 120 miles • \__ 2 significant figures • 0.002 30 kg • \__ 3 significant figures • 23,600.01 $/yr • \__ 7 significant figures

  21. 123.45987 g + 234.11 g 357.57 g 805.4 g - 721.67912 g 83.7 g Significant figures and calculations • Addition and subtraction • Report your answer with the same number of digits to the right of the decimal point as the number having the fewest to start with.

  22. Significant figures and calculations • Multiplication and division. • Report your answer with the same number of digits as the quantity have the smallest number of significant figures. • Example. Density of a rectangular solid. • 25.12 kg / [ (18.5 m) ( 0.2351 m) (2.1m) ] • = 2.8 kg / m3 • (2.1 m - only has two significant figures)

  23. Rounding off numbers • After calculations, you may need to round off. • If the first insignificant digit is 5 or more, • - you round up • If the first insignificant digit is 4 or less, • - you round down.

  24. Rounding off If a set of calculations gave you the following numbers and you knew each was supposed to have four significant figures then - 2.5795035 becomes 2.580 34.204221 becomes 34.20 1st insignificant digit

  25. Extensive and intensive properties • Extensive properties • Depend on the quantity of sample measured. • Example - mass and volume of a sample. • Intensive properties • Independent of the sample size. • Properties that are often characteristic of the substance being measured. • Examples - density, melting and boiling points.

  26. Physical properties • Properties that do not involve substances changing into another substance. • Examples • color density • odor melting point • taste boiling point • feel compressibility

  27. Chemical properties • Properties that involve substances changing into another substance. • Chemical Reaction - one or more substances are changed into other substances. • Example A chemical property of wood is it’s ability to burn - combustion. wood + oxygen carbon dioxide + water + heat ReactantsProducts The reactants and products are very different.

  28. Mass Density = Volume Density • Density is an intensive property of a substance based on two extensive properties. • Common units are g / cm3 or g / mL. • g / cm3 g / cm3 • Air 0.0013 Bone 1.7 - 2.0 • Water 1.0 Urine 1.01 - 1.03 • Gold 19.3 Gasoline 0.66 - 0.69 cm3 = mL

  29. Chapter 2 Atoms, Molecules and Ions

  30. Dalton’s atomic theory • All matter is composed of atoms -- the smallest particle of an element that takes part in a chemical reaction. • All atoms of an element are alike. • Compounds are combinations of atoms of one or more elements. The relative number of atoms each element is always the same. • Atoms cannot be created or destroyed by a chemical reaction. They only change how they combine with each other.

  31. Radioactivity • One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie (1876-1934). • She discovered radioactivity, the spontaneous disintegration of some elements into smaller pieces.

  32. Types of Radioactive Emissions

  33. Structure of the atom • Atoms have a specific arrangement. • Nucleus Small, dense, positively charged • in the center of an atom. • Contains protons (+) and neutrons • Electrons Surround the nucleus. • Negative charge.

  34. Atomic number Atom symbol Atomic weight Atomic Number, Z • All atoms of the same element have the same number of protons in the nucleus, Z 13 Al 26.981

  35. Mass Number, A • Mass Number(A) = # protons + # neutrons • A boron atom can have A = 5 p + 5 n = 10 amu

  36. Hydrogen Isotopes Hydrogen has 3 isotopes 1 proton and 0 neutrons, protium 1 1H 1 proton and 1 neutron, deuterium 21H 1 proton and 2 neutrons, tritium radioactive 31H

  37. La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Modern periodic table 1 2 13 14 15 16 17 18 I A II A III A IV A V A VI A VIIA 0 H He 1 2 3 4 5 6 7 Li Be B C N O F Ne 3 4 5 6 7 8 9 10 11 12 III B IVB V B VIB VIIB VIII B IB IIB Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe * Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn + Fr Ra Lr * +

  38. The known elements • 112 elements are currently known • 89 are metals • 31 are radioactive • 22 are synthetic (all radioactive) • 11 occur as gases • 2 occur as liquids • Let’s take a look at them on the table.

  39. He B C N O F Ne Si P S Cl Ar Ge As Se Br Kr At Rn Metals H Li Be Na Mg Al K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te Xe I * Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po + Fr Ra Lr La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb * Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Ac +

  40. Nonmetals H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe * Cs Ba Ly Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn + Fr Ra Lr Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb * La Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Ac +

  41. Semimetals H H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te Xe I * Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn + Fr Ra Lr * La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No +

  42. Solid Liquid Gas Elemental states atroom temperature H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe * Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn + Fr Ra Lr * La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No +

  43. A group or family Groups are assigned Roman numerals with an A or B I A II A III A IV A V A VI A VIIA 0 H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar III B IVB V B VIB VIIB VIII IB IIB K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Lr La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No

  44. A row or period Periods are assigned numbers H He 1 2 3 4 5 6 7 Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Lr La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No

  45. Alkali metals Alkaline earth metals Halogens Noble gases Common group names I A II A III A IV A V A VI A VIIA 0 He H Li Be B C N O F Ne Na Mg Al Si P S Cl Ar III B IVB V B VIB VIIB VIII B IB IIB K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Lr La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No

  46. Molecules • When atoms of nonmetals combine to form compounds, molecules result. • A molecule • is the smallest unit of an element or a compound. • has the chemical properties of the element or compound. • does not have a net electrical charge.

  47. Ions • Ions are charged particles formed by the transfer of electrons between elements or combinations of elements. • Cation - a positively charged ion. • Ca Ca2+ + 2e- • Anion - a negatively charged ion. • F2 + 2e- 2F-

  48. Polyatomic ions • A special class of ions where a group of atoms tend to stay together. (memorize the common ones) • NH4+ ammonium • NO3- nitrate • SO42- sulfate • OH- hydroxide • O22- peroxide • Your book contains a more complete list.

  49. Naming inorganic compounds • When an element forms only one compound with a given anion. • name the cation • name the anion using the ending (-ide) • NaCl sodium chloride • MgBr2 magnesium bromide • Al2O3 aluminum oxide • K3N potassium nitride

  50. Polyatomic ions • When a compound contains a polyatomic ion, you simply use the given name. • NH4Cl ammonium chloride • NaOH sodium hydroxide • KMnO4 potassium permanganate • (NH4)2SO4 ammonium sulfate

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