CHM110 Principles of Chemistry Lecture Slides1-1.pptx

CHM110 Principles of Chemistry slides 21-40

1. Chemistry 110 Principles of Chemistry Chapters 1-10 THESE SLIDES HAVE BEEN MODIFIED FROM THE SLIDES PROVIDED BY IRA BLE I AND GEORGE OD IAN .

2. Chapter 1 The Language of Chemistry Learning O bjectives • Describe the characteristics of elements, compounds, a nd mixtures. • Name the units of the metric system and convert them into the un its of other systems. • Describe the relation between uncertainty and s ignificant figures. • Use scientific notatio ns in expressing numbers and doing calculations. • Use the u nit-conversion method in solving problems. • Define mass, volume , density, temperature, and heat, and describe how they are measured.

3. Observations: recording what you see, includes measurements Hypothesis: statement abou t what you think the observations mean Experimental tests: methods that result in data that wil l test the hypothesis Theory: a mode l that uses the experimental data an d observations that verify the hypothesis Chapter 1 The Lang uage of Chemistry 1.1 The Composition of Matter The scientific method is based on systematic measurement and calcu lation.

4. 1.1 T he Compo sition of Matter Studying chemistry requires the con sideration of • Composition: Wha t a compound is made of • Structure: How are the elements connected • Properties: What are the characteristics • Physical Properties • Chemical Prop erties • Reactions: What other substances can it interact with

5. 1.1 The Composition o f Matter In order to develop an understanding of chemical p rocesses, one must study the properties o f pure substances . Pure substances may be obtained by a variety of “separation methods”: Chromatogra phy Distillation Filtration

6. 1.1 The Composition of Matter Pure substances have unique and consist ent physical and chemical properties . Physical Properties : •Melting P oint •Boiling Poi nt •Color •Density Physical change can result in a chan ge of state or size, but not a change in composition of a substance. Lithium Oil Water Gas Liquid Solid Nitric oxide NO 2

7. •Ability to chemically rea ct with other pure subst ances. •In a chemical rea ction, substances lose their chemical identities and form new substances with ne w physical and chemical properties. 1 .1 The Composition o f Matte r Chemical Property :

8. A mixture can be either homogeneous (a solution ) or heterogeneous : a pur e substance can be either an element or a compound (a decomposable pure substance). Elements: Substances that cannot be further decomposed • a substance that can neither be separated chemically nor created by combining si mpler substances Compounds: Decomposabl e pure substances • combined substances in fixed p roportions • made of element s 1.1 The Composition o f Matter Matter can either be a pure subs tance or is a mixture of pure substances.

9. • Elements are represented by a 1 or 2 letter symbol • First letter capi talized, second letter lower case • Generally first letter (and second) of element • C is for C arbon • N is for N itrogen • Ca is for Calci um • Br is for Bromium 1.1 The Composition of Matt er Elements

10. Common Name Symbol Symbol Origin silver Ag argentum gold Au aurum iron Fe ferrum mercury Hg hydrargyru m potassium K kalium sodium Na natrium lead Pb plumbum tin Sn stannum antimony Sb stibium tungsten W wolfram 1.1 The Composition o f Matter Some elements are named using symbols that a re derived from Latin, German, Greek, o r Arabic Table 1.1 Common Names of the Elements Whose Symbols Are Derived from La tin, German, Greek, or Arabic Names

11. A mixture is composed of at least two pure substances and is either homogeneous (visibly continuous) or heterogeneous (visi bly discontinuous) There are only two kinds of pure substances: elements and compounds. An element can neither be dec omposed into simpler pure substances nor created by combining simpler substances. Elements combine to form compounds, which are substances containing fixed proport ions of their constituent elements. The composition of a given compound is always the same, regardles s of where or h ow the substance may have formed. A compound can be decompose d, by chemical means, into simpler pure substances. The physical and chemical properties of compounds are always different from those of the e lements from which they were formed. Elements are identified by symbols derived fr om their English, Latin, Arabic, Greek, or Ger man names. 1 .1 The Composition of Matte r Concept Checklist:

12. A measurement is always expressed as a number (containing a certain number of significant digits) accompanied by a unit (s uch as inches). The set of units used in mak ing scientific measurements is called the Système International d’U nités, or simply, SI units. Chapter 1 The Language o f Chemistry 1.2 Measurement and the Metric System

13. Fundamental Quantit y Unit Name Symbol length meter m mass kilogram kg temperature kelvin K time second s amount of subst ance* mole mol electric curren t ampere A luminous intensity candela cd *The mole is a chemical quant ity that will be covered in Chapter 4. 1.2 Measurement and the Metric System Table 1.2 Fundamental Units of the Modern Metri c System All other units are derived from these units: Area = m 2 Volume = m 3 Density = kg ൗ m 3 Velocity = m Τ s

14. Quantity Unit Symbol SI definition SI equivalent length Ångström Å 10 -10 m 0.1 nanometer volume liter L 10 -3 m 3 1 decimeter 3 energy calorie cal (kg·m 2 ·s -2 )* 4.184 joules *A centered dot ( ·) is used to denote multiplication in derived units. 1.2 Measurement and the Me tric System Some non-SI units are still in c ommon use: Table 1.3 Non-SI Units in Common Use

15. Multiple o f part of ten Prefix Symbol 1,000,000,0 00 giga - G 1,000,000 mega - M 1,000 kilo - k 100 hecto - h 10 deka - da 0.1 deci - d 0.01 centi - c 0.001 milli - m 0.000001 micro - μ 0.000000001 nano - n 0.0000000000 01 pico - p 1.2 Measurement and the Metric System In the metric system of expressing numbers, all units can be prefixed by a multiple of 10. These multiples are written as prefixes immediately before t he unit itself. The followin g are the same number: 1.0 x 10 -3 m = 1.0 mm Table 1.4 Names Used to Express M etric Units in Mu ltiples or Parts of Ten

16. Express (a) 0.005 se cond (s) in millisecond (ms) (b) 0.02 mete r (m) in centimeter (cm) (c) 0.007 liter (L) i n milliliter (mL) 1.2 Measurement and the Metric System Example 1.1 Using metric system prefi xes

17. Chapter 1 The Language o f Chemistry 1.3 Measurement, Uncertainty, and Significant Figures Unless a measurement is made by counting a small number of objects, a measurement will always contain some uncertainty , or error. This error is expressed by the number of significant dig its reported for the measured number. 4 ± 1 g = 4 g 4 ± 0.1 g = 4.0 g 4 ± 0.001 g = 4.000 g 4 ± 0.0001 g = 4.0000 g 1 significant figure 2 significant fi gures 4 significant figures 5 significant figures

18. • A trailing zero, as in 4.130, is significant. • A zero within a number, as in 35.06 cm, is significant. • A zero before a digit, as in 0. 082, is not significant. • A number ending in zero with no decimal point, as in 20, is ambiguous. Ambiguities of this last type can be prevented by the use of scientific or exponentia l notation. Numbers obtained by counting, or exact def initions such as 12 inches = 1 foot, or 2.54 cm = 1 inch, have an infinite number of s ignificant digits. 1.3 Measurement, Uncertainty, an d Significant Figures The number of signifi cant digits in a number can be determined by the following rules:

19. • Also called exponential notation • convenient method for preventing am biguity in the reporting of measurements • useful in the simplification of the manipulation of very large and very small numbers Chapter 1 The Lang uage of Chemistry 1.4 Scient ific Notation