CHEM 101 1st Edition Lecture 2Outline of Last Lecture I. Introduction to Matter, Compounds, and Chapter 1Outline of Current Lecture II. Introduction to Mixtures III. The Periodic Table of Elements and its importanceIV. Regions of the Periodic TableV. The Scientific Method VI. The Metric SystemVII. Units and prefixesCurrent LectureVIII. Mixture: is 2 or more pure substances that are physically combined but not chemically bonded together. A. Mixtures have 2 subclasses:a. Homogeneous Mixtures: are mixtures in which the substances that compose it are so evenly distributed that a sample from any part of the mixture will be chemically identical to a sample from any other part. i. Alloys: are homogeneous mixtures of several metallic elements. ii. Gasses can also form homogeneous mixtures.b. Heterogeneous Mixtures: is one in which the composition varies fromone region of the sample to another.IX. ThePeriodic Table of Elements: This shows all the known chemical elements. Several patterns can be deciphered within the periodic table. It allows us to predict:1. Chemical reactions2. Formulas of many compounds3. Relative sizes of atoms and moleculesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.4. Whether compounds will dissolve in water or oilii. Dmitri Mendeleev was the Russian Scientist that developed and organizedthe periodic table that we use today. He was even able to predict the existence of elements that had not been discovered yet!b. Atomic Symbols: Letters of ‘symbols’ are used to represent the elements of the periodic table. Most are derived from the elements name (He- Helium). However,some elements such as gold (Au) and sodium (Na) are represented by symbols derived from the Latin names of the element. c. Atomic Number: is the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table. This number is normally found in the top right hand corner of each elemental square. d. Atomic Mass: the mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutronsin the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.1. For example Sodium (Na) has an atomic number of 11, and an atomic mass of 22.990NOTE**you will need to memorize elements (symbol, proper spelling of elemental name and atomic number) 1-38 and elements 49-56X. Regions of the Periodic Tablea. It is important to be able to distinguish between elements that are metals, nonmetals or metalloids. i. Metals: Share the following properties:1. They are good conductors of electricity and heat2. They are solid at room temperature3. They generally have very high melting pointsa. Metals are able to conduct electricity because the metal atoms form metallic bonds to each other in which the electrons are free to move from one atom to another. This model is referred to as the sea of electrons.ii. Nonmetals: Share the following properties:1. They are not good conductors2. They can be found as liquids, solids or gases depending on the element.3. Generally they have lower melting points than metalsiii. Metalloids: Have properties between the two extremes shown by metals and nonmetals. There isn’t a sharp line that distinguishes a metalloid from a metal or nonmetal. Rather, the changes are gradual in the physical properties of the elements.1. Examples of Metalloid elements:a. B, Si, Ge, As, Sb, Te, Po, and Ativ. Noble Gases: any of the gaseous elements helium, neon, argon, krypton, xenon, and radon, occupying Group (18) of the periodic table. They were long believed to be totally unreactive but compounds of xenon, krypton, and radon are now known. They do not react easily. XI. The Scientific Method – Critical Thinkinga. The Scientific Method: is a systematic method for problem solving and the steps are as follows:1. Determine the nature of the problem.2. Collect and analyze all relevant data.3. Form an educated guess, called a hypothesis, as to what the answer to the problem faced is. 4. Test your hypothesis.5. If your hypothesis holds up to testing, you are finished. If not, go back to step two. a. NOTE: for a hypothesis to hold up to testing the test would have to be replicable. XII. Introduction to Chapter 2: Reactions, Properties and Changesa. Chemical Change: When matter undergoes a chemical reaction and forms a new substance we call this a chemical change. i. Chemical properties: are used to describe the potential chemical reactions a substance can undergo. Below are some examples:1. Flammability: the potential to react rapidly with O and burst into flames, producing light and heat.2. Rusting: the ability of a substance to react with O, forming rust3. Explosiveness: the tendency of compounds such as nitroglycerin to decompose violently, producing gasses that expand rapidly.b. Physical Changes: occurs when matter is transformed in a way that does not alterits chemical identity, such as when matter changes between a solid, liquid or gaseous states. i. Physical properties: can be measured without changing the chemical identity of the substance. Examples of physical properties are:1. Color2. Melting point / Boiling point3. Odor4. Refractive index: a measure of how much light is bent when it passes through a transparent substance.5. Hardness6. Texture7. Solubility 8. Electrical properties9. Density**c. Density: Mass of a unit volume of a material substance. It is calculated by dividing an object's mass by its volume. In the International System of Units, and depending on the units of measurement used, density can be expressed in gramsper cubic centimeter (g/cm3) or kilograms per cubic meter (kg/m3).d. Mass: the mass of a sample is a measure of how much matter is contained in that sample. The unit used for mass is grams (g). i. Not to be confused with weight:e. Weight: is the measure of how strongly gravity is pulling on matter. If an object is moved to a location where gravity pulls less the objects weight decreases.XIII. The Standard Units of Measure: NEED TO KNOW** 1. Mass – unit of measure: Grams (g)2. Volume- unit of measure: Liter (L)3. Distance- unit of measure: Meters (m)4. Time- unit of measure: Seconds (s)ii. SI- International System or Metric System. The English system you need tofamiliarize yourself with is:1.