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Introduction to Chemistry: Key Concepts on Matter, Measurement, and Properties

This chapter provides a comprehensive overview of foundational concepts in chemistry. It covers the scientific method, classifications of matter, properties of matter, and measurement units, including metric system prefixes and temperature conversions. Readers will learn about states of matter—solid, liquid, gas, and plasma—and the distinction between elements, compounds, and mixtures. The chapter further explains physical versus chemical properties, changes of state, and the importance of significant figures in measurements. It concludes with practical applications in density calculations and unit conversions.

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Introduction to Chemistry: Key Concepts on Matter, Measurement, and Properties

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  1. Chapter 1 The Study of Chemistry

  2. Topics • Introduction • Scientific Method • Classifications of Matter • Properties of Matter • Units of Measurement – Metric system • Temperature Conversion • Metric Conversion (Prefixes) • Accuracy vs. Precision • Significant Figures • Density

  3. States of Matter • Solid • Liquid • Gas • Plasma

  4. ATOM • Is the simplest unit of matter.

  5. Definitions • Elements – can’t be decomposed further into simpler substances • - 111 elements presently • - Ds (element 110) • - Rg (element 111) • Compound – combination of 2 or more elements

  6. Definitions • Mixtures – combinations of 2 or more substances (ex. sugar in water) • 2 Types of Mixtures • 1. Homogenous Mixtures (solutions) = 1 phase • 2. Heterogeneous Mixtures = > 2 phases

  7. SOLUTIONS • Homogeneous mixtures are called SOLUTIONS.

  8. Solution • Solution – homogenous mixture • A solution is not necessarily a liquid. Can be gas or solid.

  9. Physical vs. Chemical Properties • Physical properties – can be measured w/o changing identity and composition of substance (ex. Boiling pt.,freezing pt., color, odor, density, hardness) • Chemical properties – describe how substance reacts or changes to form other compounds (ex. Flammability, toxicity)

  10. Changes of State and Properties • Physical changes – does not change composition of compound • Chemical changes – converts to a different chemical substance • Intensive Properties – independent of amt. (ex. Density, Temperature, Melting Pt) • Extensive Properties – dependent on amt. (ex. Mass, Volume)

  11. Units of Measurement • Mass – grams; kilogram • Length – centimeter; meter • Volume – milliliter or cubic centimeter (cm3) • Temperature – Celcius; Kelvin

  12. Prefixes in Metric System • Mega - million • Kilo - 1,000 • Hecto - 100 • Deka - 10 • ----- - 1 (liter, gram, meter) • Deci - 1/10 or 0.1 • Centi - 1/100 or 0.01 • Milli - 1/1000 or 0.001

  13. Temperature Conversions • 0 oC = 273.15 K • oF = 1.8 oC + 32

  14. Things to Remember! • 1 milliliter = 1 cc • 1000 milliliter = 1 liter • 0 oC = 32 oF = 273.15 K

  15. Precision vs Accuracy • Accuracy – when acquired value agrees with true value • Precision – when acquired values exhibit reproducibility

  16. Significant Figures • More significant figures = more certainty • Helps in determining how to round measured values and still precise

  17. SIGNIFICANT FIGURES • In counting and definitions, there are an infinite number of sig figs • In measurements, the number of sig figs consists of all certain and the first uncertain digits • Unit conversions do not determine # of sig. figs.

  18. Rules of Significant Figures • 1. Non-zero integers always count. • Ex. 1234.5 grams = 5 Sig. Figs. • 2. Captive zeros are always significant. • Ex. 100.3 grams = 4 Sig. Figs.

  19. Rules of Significant Figures • 3. Leading zeros are NEVER significant. • Ex. 0.6780 grams = 4 Sig. Figs. • 4. Trailing zeroes are significant ONLY if there is a decimal point • Ex. 12.0 grams = 3 Sig. Figs • 120 grams = 2 Sig. Figs

  20. Rules of Significant Figures • 5. Exact numbers (obtained by counting) are infinite and do not determine the number of significant figures. • Example: 4 cows = ?

  21. Determine the # of Sig. Fig. • 200.0 • 1050 • 3003 • 0.0006 • 10,000 • 0.5

  22. Rules of Significant Figures • Multiplication/Division • Answer will have the same # of sig figs as the value with the least # of sig figs • Ex: 3.8 x 200.0 = 2 Sig. Figs.

  23. Rules of Significant Figures • Addition/Subtraction • Answer has the same # of decimal places as the number with the least # of decimal places • Ex. 3.1 + 2.500 + 5.76 = 11.4

  24. Order of Operations • Parenthesis • Multiplication/division • Addition/subtraction

  25. Rounding • Look only to the right of the number you are rounding to: • - If 5 or more, round up • - If less than 5, round down

  26. General Rule • Carry ALL figures through to the end of a problem. Round the final answer to the correct number of significant figures

  27. Problem • Indicate the number of sig. figs. in each of the following measured quantities: • A. 358 kg • B. 0.054 s • C. 6.3050 cm • D. 0.0105 L • E. 7.0500 x 10-3 m3

  28. Problem • Round each of the following numbers to 4 sig. figs. And express the result in standard exponential notation. • A. 102. 53070 • B. 656, 980 • C. 0.008543210 • D. 0.000257870 • E. - 0. 0357202

  29. Problem • Carry out the following operations and express the answer with the appropriate number of sig. figs. • A. 12.0550 + 9.05 • B. 257.2 – 19.789 • C. (6.21 x 103)(1.1050) • D. 0.0577 / 0.753

  30. Density • Is the amount of mass in a unit volume of the substance • Is affected by Temperature. • The higher the temp., the lower the density. D = mass of substance = grams volume of substance mL or cm3

  31. Density • Density = mass volume = gram mL

  32. Different ways of calculating volume • I. For solids with regular shapes: • A. For a cube: Vcube = s3 • B. For a rectangular solid, V = L x W x H • C. For a cylinder: V= pr2h • D. For a sphere: V = 4/3 pr3

  33. Different ways of calculating volume • II. For an Irregular Solid • Water displacement

  34. Different ways of calculating volume • III. For a liquid • Use of graduated cylinder, beaker, pipet or buret.

  35. Problem • A cube of osmium metal 1.500 cm on a side has a mass of 76.31 grams at 25 oC. What is its density in g/cm3 at this temperature?

  36. Problem • The density of titanium metal is 4.51 g/cm3 at 25 oC. What mass of titanium displaces 65.8 mL of water at 25 oC?

  37. Problem • The density of benzene at 15 oC is 0.8787 g/mL. Calculate the mass of 0.1500 L of benzene at this temperature.

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