What is Chemistry ?

1. What is Chemistry ? Chapter 1

2. What is Chemistry? • The study of the matter, its composition, properties, and the changes it undergoes. • Has a definite affect on everyday life - taste of foods, grades of gasoline, etc. • Living and nonliving things are made of matter.

3. 5 Major Areas of Chemistry • Analytical Chemistry- concerned with the composition of substances. • Inorganic Chemistry- primarily deals with substances without carbon • Organic Chemistry- essentially all substances containing carbon

4. 5 Major Areas of Chemistry • Biochemistry- Chemistry of living things • Physical Chemistry- describes the behavior of chemicals (ex. stretching); involves lots of math! Boundaries not firm – they overlap and interact

5. - Page 8

6. What is Chemistry? • Pure chemistry- gathers knowledge for the sake of knowledge • Applied Chemistry- is using chemistry to attain certain goals, in fields like medicine, agriculture, and manufacturing – leads to an application • Nylon, Aspirin (C9H8O4), Technology

7. Why Study Chemistry? • Everyone and everything around us involves chemistry – explains our world • What in the world isn’t Chemistry? • Helps you make choices; helps make you a better informed citizen • Used to attain a specific goal

8. Why Study Chemistry? • Give examples in your daily life that involve use of chemistry, and things that do not?

9. What is matter ? • Matter is anything that: • Has mass • takes up space • What about heat?

10. What is matter ? • Mass = a measure of the amount of “stuff” (or material) the object contains (don’t confuse this with weight, a measure of gravity) • Volume = a measure of the space occupied by the object

11. Types of Matter • Substance- a particular kind of matter – pure • Mixture- more than one kind of matter

12. Pure Substances Pure Substancesare either: a) elements, or b) compounds

13. Pure Substance • Elements- simplest kind of matter • cannot be broken down any simpler and still have properties of that element! • all one kind of atom.

14. Symbols & Formulas • Currently, there are 118 elements • 94 occur naturally • Elements have a 1 or two letter symbol, and compounds have a formula. • An element’s first letter is always capitalized; if there is a second letter, it is written lowercase: B, Ba, C, Ca, H, He • Some names come from Latin or other languages

15. Pure Substance • Compoundsare substances that can be broken down only by chemical methods • when broken down, the pieces have completely different properties than the original compound. • made of two or more atoms, chemically combined (not just a physical blend!)

16. Types of Matter • Mixtures are a physical blend of at least two substances; have variable composition. They can be either: • Heterogeneous – the mixture is not uniform in composition • Example: Chocolate chip cookie, gravel, soil.

17. Types of Matter • Homogeneous - same composition throughout; called “solutions” • Examples: Kool-aid, air, salt water • Every part keeps it’s own properties.

18. Types of Matter • Solutions are homogeneous mixtures • Mixed molecule by molecule, thus too small to see the different parts • Can occur between any state of matter: gas in gas; liquid in gas; gas in liquid; solid in liquid; solid in solid (alloys), etc.

19. Separating Mixtures • Some can be separated easily by physical means: rocks and marbles, iron filings and sulfur (use magnet) • Differences in physical properties can be used to separate mixtures.

20. Filtration: Separates solid substances from liquids and solutions.

21. Separation of a Mixture Components of dyes such as ink may be separated bypaper chromatography.

22. Separation of a Mixture Distillation:takes advantage of different boiling points. NaCl boils at 1415 oC

23. Describing Matter • Properties used to describe matter can be classified as: • Extensive – depends on the amount of matter in the sample • Mass, volume, calories are examples • Intensive – depends on the type of matter, not the amount present - Hardness, Density, Boiling Point

24. Physical vs. Chemical Properties • Words that describe matter (adjectives) • Physical Properties- a property that can be observed and measured without changing the material’s composition. • Examples- ?

25. Physical vs. Chemical Properties • Chemical Properties- a property that can only be observed by changing the composition of the material. • Examples- ?

26. Physical vs. Chemical Property • Examples: • melting point • flammable • density • magnetic • tarnishes in air

27. Changes in Matter Chemical and Physical Changes

28. Physical vs. Chemical Change • Physical change will change the visible appearance, without changing the composition of the material. • Can be reversible, or irreversible • Examples? • Chemical change - a change where a new form of matter is formed. • Examples?

29. Physical and Chemical Changes

30. Matter MATTER no yes Can it be physically separated? PURE SUBSTANCE MIXTURE no yes Can it be chemically decomposed? yes no Is the composition uniform? Compound Element Homogeneous Mixture (solution) Heterogeneous Mixture

31. Substances and Mixtures • Examples: • Graphite (all C atoms) • Diamond (a form of carbon) • sugar (sucrose) • paint • gasoline • Sulfur • Rust

32. States of matter • Solid- matter that can not flow (definite shape) and has definite volume. • Liquid- definite volume but takes the shape of its container (flows). • Gas- a substance without definite volume or shape and can flow. • Vapor- a substance that is currently a gas, but normally is a liquid or solid at room temperature.

33. 4th state:Plasma - formed at high temperatures; ionized phase of matter as found in the sun

34. Products manufacturedusing plasmas impact our daily lives: • Computer chips and integrated circuits • Computer hard drives • Electronics • Machine tools • Medical implants and prosthetics • Audio and video tapes • Aircraft and automobile engine parts • Printing on plastic food containers • Energy-efficient window coatings • High-efficiency window coatings • Safe drinking water • Voice and data communications components • Anti-scratch and anti-glare coatings on eyeglasses and other optics

35. sublimation deposition Phase Changes freezing evaporation SOLIDLIQUIDGAS melting or fusion condensation

36. The Scientific Method • A logical approach to solving problems or answering questions. • Starts with observation- noting and recording information and facts • hypothesis- a proposed explanation for the observation; must be tested by an experiment

37. Steps in the Scientific Method 1. Observations (uses your senses) a)quantitative involves numbers = 95oF b)qualitative is word description = hot 2. Formulating hypotheses (ideas) - possible explanation for the observation, or “educated” guess 3. Performing experiments (the test) - gathers new information to help decide whether the hypothesis is valid

38. Scientific Method • “controlled” experiment- designed to test the hypothesis • only two possible answers: • hypothesis is right • hypothesis is wrong • We gather data and observations by doing the experiment • Modify hypothesis - repeat the cycle

39. Scientific Method • We deal with variables, or factors that can change. Two types: • Manipulated variable (or independent variable) is the one that wechange 2) Responding variable (or dependent variable) is the one observed during the experiment • For results to be accepted, the experiment needs to always produce the same result

40. Scientific Method • Outcomes over the long term… • Theory(Model) • A set of well-tested hypotheses that give an overall explanation of some natural phenomenon – not able to be proved • Natural Law (or Scientific Law) • The same observation applies to many different systems; summarizes results

41. Law vs. Theory • A law summarizes what has happened. • A theory (model) is an attempt to explain why it happened – this changes as new information is gathered.

42. - Page 22 The procedure that is used to test the hypothesis Using your senses to obtain information Hypothesis is a proposed explanation; should be based on previous knowledge; an “educated” guess Tells what happened A well-tested explanation for the observations; cannot be proven due to new discoveries