1. Introduction to Chemistry

2. I. Chemistry is a Physical Science
Objectives:
Define chemistry.
List examples of the branches of chemistry.
Compare and contrast basic research, applied research, and technological development

3. What is Chemistry?
Chemistry = the study of the composition, structure, and properties of matter and the changes it undergoes.

4. 6 Branches of Chemistry
Organic chemistry = study of carbon-containing compounds
Inorganic chemistry = study of all substances not classified as organic, mainly those compounds that do not contain C
Physical chemistry = study of the properties and changes of matter and their relation to energy
Analytical chemistry = identification of the components and composition of materials
Biochemistry = study of substances and processes occurring in living things
Theoretical chemistry = use of mathematics and computers to understand the principles behind observed chemical behavior and to design and predict the properties of new compounds.

5. Science vs. Technology
Science includes knowledge in the major disciplines, such as biology, chemistry, and physics.
Technology is the application of that knowledge for practical purposes.
Basic research = research conducted for the sake of knowledge only and not to meet practical goals
Applied research = research conducted to meet goals defined by specific needs
Technology = applies existing knowledge to make life easier or more convenient

6. II. Matter and Its Properties
Objectives:
Distinguish between the physical properties and chemical properties of matter.
Classify changes of matter as physical and chemical.
Explain the gas, liquid, and solid states in terms of particles.
Distinguish between a mixture and a pure substance.

7. Energy vs. Matter
EVERYTHING that you see or sense is either matter or the interaction of energy and matter!
Energy = the ability to cause change or the ability to do work.
Matter = anything that has mass and takes up space.

8. Classification of Matter
1) Pure substance = a type of matter that has a consistent, fixed composition no matter where the sample is obtained.
a) Ex: water (a pure substance) is ALWAYS 11.2% hydrogen and 88.8% oxygen (by mass).
So a molecule of water from India has the same compositions as a molecule of water from Canada.
b) PURE SUBSTANCES are either elements or compounds

9. Classification of Matter
2) Element = pure substance made of only one kind of atom. a) atom = smallest unit of an element that maintains the properties of that element.

10. Classification of Matter
3) Compound = a pure substance that is made from the atoms of two or more elements that are chemically combined. a) Individual elements lose their individual properties and take on the new properties of the compound that is formed.

11. b) Ex: sodium (an element) is a highly
b) Ex: sodium (an element) is a highly reactive metal and chlorine (an element) is a poisonous gas; chemically combined they form sodium chloride (a compound) which is common table salt.

12. Classification of Matter
4) Mixture = a blend of two or more pure substances that are physically combined where each pure substance retains its own identity and properties
Ex: silver coins + gold coins = mixture; the silver coins are still silver coins and the gold coins are still gold coins.

13. V. Classification of Matter
Characteristics of mixtures:
Represent physical combinations of two more substances
Substances do not lose their original properties.
Substances can be separated by physical means.
Two types of mixtures are homogeneous and heterogeneous.

14. 5) Homogeneous mixture (solution) = a mixture that is uniform in composition throughout an entire sample.
Ex: if you were to take one scoop out of one area of a homogeneous mixture and a second scoop out of a different area of the same sample, the composition of each scoop would be essentially the same.
Ex: salt water, air, window glass.

15. Homogeneous mixture cont.
Also called solutions – consist of a solute (dissolved material) in a solvent (dissolving material)
Important symbol in chemistry is
the subscript “aq”, which stands for aqueous.
An aqueous substance is one that is dissolved in water … AKA a solution!

16. NaCl(s) – This formula represents a solid substance, the compound NaCl in a solid form.
NaCl(aq) – This formula represents a homogeneous mixture of NaCl and water.

17. 6) Heterogeneous mixture = a mixture that is NOT uniform in composition throughout an entire sample.
Ex: chicken soup, sands, soil.

20. How would you classify the following matter?
ASPIRIN (C9H8O4) is composed of 60% carbon, 4.5% hydrogen, and 35.5% oxygen by mass, regardless of its source. Is aspirin a mixture or a pure substance? Element or compound?
Pure substance – constant composition
Compound

21. How would you classify the following matter?
SALT WATER Is salt water a mixture or a pure substance? What type of mixture?
Mixture – can be separated by evaporation
Homogeneous mixture

22. Properties of Matter What is a property?
2 methods of grouping properties
Extensive and intensive
Physical and chemical
Extensive = property that depends on the amount of matter (mass, volume)
Intensive = property that does not depend on the amount of matter present (color, melting pt., boiling pt.)

23. Properties of Matter
Physical property = a characteristic that can be observed or measured without changing the identity of a material.
Physical properties describe matter.
Ex: state, color, odor, solubility, density, melting point, boiling point, hardness, mass, texture

24. Properties of Matter
2) Chemical property = the ability of a substance to undergo a change that alters its identity.
Chemical properties describe the ability of matter to change identity.
Ex: flammability, reactivity with acid, resistance to rusting, ability to decompose.

25. Changes
Physical change = any change in a property of matter that does NOT result in a change in identity.
Ex: water freezing, water vapor condensing, wood being chopped, glass being broken, an iron rod being bent

26. Changes
2) Chemical change (chemical reaction) = a change in which one or more substances are converted into different substances with different characteristic properties.
Ex: paper burning, silver tarnishing, wood decomposing, iron rusting.

27. Chemical vs. Physical change:

28. Chemical change (chemical reaction)
Indications of a chemical change (reaction):
a) Evolution of heat and light
b) production of a gas (seen as bubbles)
c) color change
d) formation of a precipitate when two solutions are mixed.
precipitate = a solid that separates from a solution.

29. Formation of a PRECIPITATE
Precipitate of cadmium sulfide forms from clear solutions of sodium sulfide and cadmium nitrate.

30. Chemical change (chemical reaction)
2) In order for a chemical reaction to take place, the reactants must have the ability to form chemical bonds.
Parts of a chemical reaction:
REACTANTS = substances that interact with each other. On the left side of the arrow in a chemical equation.
PRODUCTS = new substances formed during reaction. On the right side of the arrow in a chemical equation.
EX: hydrogen + oxygen  water + heat

31. Chemical change (chemical reaction)
3) Law of Conservation of Matter = matter is neither created nor destroyed during ordinary chemical and physical changes.
As a result of the law of conservation of matter, the mass of the reactants in a chemical reaction must EQUAL the mass of the products.
If you START off with 10g of matter before a physical or chemical reaction, you will END up with 10g of matter.
These changes don’t create or destroy atoms, they only change how the atoms are bonded to each other!

32. Energy Changes
Energy = the ability to cause change or the ability to do work
Heat = form of energy
Heat FLOWS from objects with a high temperature to objects with a lower temperature.

33. Energy Changes
NOTE: A chemical change is ALWAYS accompanied by a change in ENGERGY!! 2) Chemistry deals with the chemical energy stored in matter and with either the effects on matter or the production of energy from matter.

34. Energy Changes
3) Activation energy is the energy needed to start a chemical reaction.
All chemical reactions require energy to begin!
Enough energy is available from the environment to start some reactions.
For others, additional energy must be added before the reaction will begin.

35. Energy Changes 4) Endothermic process = a process that absorbs heat
The products have MORE energy than the reactants.
Energy must be absorbed as the products form.
The container in which an endothermic reaction is taking place will feel cold.
Ex: chemical cold packs, ice melting.

36. Energy Changes 5) Exothermic process = a process that releases heat.
The reactants have MORE energy than the products.
Energy must be released as the products form.
The container in which an exothermic reaction is taking place will feel hot.
Ex: chemical hot packs, lighting a match.

37. Exothermic process Ex: CH4 (g) + 2O2 (g)  CO2 (g) + 2H2O (g) + ENGERY
REACTANTS
PRODUCTS

38. 4 States of Matter Solid = definite volume and definite shape
Liquid = definite volume but no definite shape
Gas = neither definite volume nor definite shape
Plasma = high-temperature physical state of matter in which atoms lose their electrons

39. III. Elements Objectives:
Use a periodic table to name elements, given their symbols.
Use a periodic table to write the symbols of elements, given their names.
Describe the arrangement of the periodic table.
List the characteristics that distinguish metals, nonmetals, and metalloids.

40. For a chemist, the periodic table is the most useful source of information about the elements.
Groups = families = vertical columns (these elements have similar properties)
Periods = horizontal rows
Symbols are sometimes derived from Latin.

42. Write the symbol, group, and period for each of the following:
Potassium
Oxygen
Aluminum
Cesium
Sodium
Sulfur
Zinc
Cobalt
Neon
Iodine

43. Types of Elements 3 Types:
Metals: good conductor of heat and electricity
other properties include: malleability, tensile strength, ductile, solid at room temp. silvery or grayish luster, reactivity
Majority of periodic table
Nonmetals: poor conductor of heat and electricity
Other properties include: many are gases; solids are brittle
Top right corner of periodic table

44. Types of Elements Metalloids: properties of metals and nonmetals
Other properties include: semiconductors of electricity, used in computers and calculators
6 elements form stair steps (B, Si, Ge, As, Sb, and Te)

45. Noble Gases
Noble gases = group 18
Unreactive
Gases at room temp.

47. Complete p. 23 #1,2,4-15, 20-21 Write and UNDERLINE the question
If you do not finish, the book is online 