Welcome to chemistry

Transcription

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2 Welcome to chemistry

3 Science a search for facts about the world around us understanding the past, predicting the future

4 Aristotle ( B.C.) one can work out all the laws that govern the universe by pure thought

5 Roger Bacon (1300 s) science should base its reasoning on experimental evidence. science replaces philosophy

6 science A procedure for processing and understanding certain types of information If there is no test for its possible wrongness, then it is not scientific.

7 The Scientific Method Experiment Observation Hypothesis Theory Law

8 The Scientific Method Experiment Observation Hypothesis Theory Law click on any underlined word for its definition

9 Science and Technology science is a method of answering theoretical questions technology is a method of solving practical problems.

10 chemistry The study of matter, its structure, properties, composition and changes that matter undergoes.

11 Chemists are problem solvers Problem: the paper in 40% of old library books is crumbling how to preserve the crumbling books

12 paper is made from cellulose cellulose is formed from long chains of glucose (C 6 H 12 O 6 )

13 Al 2 (SO 4 ) 3 is used to prevent ink from fuzzing

14 Al 3+ ions interact with water to form Al (H 2 O) 6 3+

15 an equilibrium is established producing H + ions H + ions destroys cellulose ie: crumbling paper Al (H 2 O) 6 3+ [Al(OH) (H 2 O) 5 ] 3+ + H + remove H + stop the crumbling add a base remove the acid

16 Add NaOH(aq) H + OH - + H 2 O we are left with wet paper

17 Add NH 3 (g) H + + NH 3 NH + 4

18 as the pressure is reduced NH 3 (g) leaves, shifting the equilibrium producing more H + H + (aq) + NH 3 (g) NH + 4 (aq) the solution to the problem is only temporary

19 adding (C 2 H 5 ) 2 Zn(g) diethyl zinc (C 2 H 5 ) 2 Zn(g) + H 2 O ZnO (aq) + 2 C 2 H 6 2H + (aq) + O 2- (aq) H 2 O thus ZnO is a nonvolatile base that can placed on paper by a gaseous substance

20 Classifications of Matter Matter is anything that occupies space and has mass. mass - a measure of the quantity of matter Volume - space

21 Matter We define matter as anything that has mass and takes up space Pearson Education, Inc. Matter And Measurement

22 Matter Atoms are the building blocks of matter. Each element is made of the same kind of atom. A compound is made of two or more different kinds of elements Pearson Education, Inc. Matter And Measurement

23 Matter Homogeneous mixtures Compounds Mixture Substance Heterogeneous mixtures Elements

24 Matter Homogeneous mixtures Compounds Mixture Substance Heterogeneous mixtures Elements click on words for definitions

25 Physical and Chemical Properties of Matter

26 Properties A set of characteristics by which a substance can be recognized

27 Physical property can be measured and observed without changing the composition or identity of a substance Chemical property requires a chemical change in order to be observed

28 Extensive property depends on amount of material; mass and volume are examples of extensive properties Intensive property does not depend on amount of material; density and temperature are examples of intensive properties

29 Types of Changes Physical Changes These are changes in matter that do not change the composition of a substance. Changes of state, temperature, volume, etc. Chemical Changes Chemical changes result in new substances. Combustion, oxidation, decomposition, etc.

30 Chemical Reactions In the course of a chemical reaction, the reacting substances are converted to new substances Pearson Education, Inc. Matter And Measurement

31 Separation of Matter

32 Filtration In filtration, solid substances are separated from liquids and solutions Pearson Education, Inc. Matter And Measurement

33 Distillation Distillation uses differences in the boiling points of substances to separate a homogeneous mixture into its components Pearson Education, Inc. Matter And Measurement

34 Chromatography This technique separates substances on the basis of differences in solubility in a solvent Pearson Education, Inc. Matter And Measurement

35 Periodic Table of the Elements

36 Chemical Symbols abbreviations for the names of the elements the first letter is always capitalized O, Al, C, Cl, H, He.

37 An elements position on the periodic gives indications of its various physical and chemical properties

38 Main groups group numbers indentified by suffix A

39 Main group metals Alkali metals Alkaline earth metals

40 Nonmetals Halogens Noble gases

41 transition metals Lanthanides

42 Actinides transition metals Lanthanides

43 The Three States of Matter solid liquid gas

44 solid liquid gas

45 (slides that follow are linked to earlier ones)

46 law a concise verbal or mathematical statement of a relationship between phenomena that is always the same under the same conditions

47 theory a unifying principle that explains a body of facts and those laws that are based on them

48 hypothesis a tentative explanation for a set of observations leads to if then questions test of theory

49 a substance is form of matter that has a definite or constant composition and distinct properties, for example water ammonia table sugar gold oxygen

50 a mixture is a combination of two or more substances in which the substances retain their distinct indentities, for example air milk

51 the composition of a homogeneous mixture is the same throughout, for example copper (II) sulfate dissolved in water

52 a mixture of nonuniform composition is a heterogeneous mixture, for example granite Sand and iron filings

53 an element is a substance that cannot be separated into simpler elements by chemical means

54 a compound is a substance composed of atoms of two or more elements chemically united in fixed proportions