Chemistry Chapter 1 Introduction to Chemistry

How to succeed in chemistry Positive attitude: believe you can! Listen in class/take good notes Memorize what I ask you to/figure out the rest Read the chapters Self-check exercises/odds (practice) Complete homework ahead of time (so can ask questions!) Keep an organized notebooks Study!

What is CHEMISTRY?

Chemistry is… … The study of matter and the changes it undergoes C 2 H 5 OH + 3 O 2  2 CO H 2 O + Energy Reactants  Products

Matter Anything that has mass and occupies space Mass A measure of the amount of matter Weight The measure of the amount of matter in and the gravitational force exerted on the object. (product of mass and the local acceleration of gravity) In general terms: “the heaviness” of an object

Model A visual, verbal, or mathematical explanation of experimental data. Branches of Chemistry Table 1.1, p. 11 Chemistry is the “Central Science” What are chemists? Who are chemists?

You must be more than a talking head…..

Steps for Problem Solving/The “Scientific Method ”: 1.Make observations-something that is witnessed and can be recorded 2.State the problem 3.Form hypothesis-testable statements or predictions to propose possible solutions 4.Decide what is reasonable and perform experiments. (must be able to THINK CRITICALLY and creatively) 5.Analyze the data 6.Form conclusions (done/replicate, or start again?)

Figure 1.1: The various parts of the scientific method.

Type of Observation or Data Quantitative: Numerical information describing a quantity. It usually includes a number and a unit (454.6 g, 2.2 lb., 25 students) Qualitative: Describes a quality of the data such as color, odor, shape, or some other physical characteristic (granular, white)

Theory or a Law? Theory: (model) tested set of hypothesis that gives an overall EXPLANATION of some part of nature. (tells WHY it happens) –Quantum Theory Law: A summary of accepted facts of nature. (tells WHAT happened again and again and again) –Law of chemical equilibrium –Law of conservation of energy –Law of conservation of mass

Problem/Observation: This plant is dying… 1.Propose possible solutions. (or hypothesis) 1.Decide how to test them. 2.Test them. 3.Evaluate results. 4.Possibly draw conclusion.

Controlled Experiments 1.Independent Variable-the variable that will be manipulated or changed 2.Dependent Variable-the variable whose value depends on the independent variable 3.Constants-what is kept the same throughout the experiment to keep “samey samey” 4.Control-the standard that is used for comparison

Types of Research 1.Pure Research-to gain knowledge for the sake of knowledge itself 2.Applied Research-research undertaken to solve a specific problem

Ozone Case Study 1.O 2 + UVC  O O + O 2  O 3 3.O 3 + UVB or UVC  O 2 + O First three steps: normal containment of UV radiation 1.O 3 + Cl  ClO + O 2 2.ClO + O  Cl + O 2 A single chlorine molecule can break down 100,000 ozone molecules

Chemistry Chapter 3 Matter—Properties and Changes

Atom The smallest unit of an element that maintains the properties of that element Eleme nt A pure substance that cannot be broken down into simpler substances by physical or chemical means.

Top Ten

Compound A substance that is made from the atoms of two or more elements that are chemically bonded. Sucrose – C 12 H 22 O 11 Sucrose is also known as table sugar, and is used to make Gummy Bears!

Atom Combinations

Physical Change A change in a substance that does not involve a change in the identity of the substance. Example: Phase Changes

Figure 2.7: The three states of matter: solid. Solid: a form of matter that has its own definite shape and volume

Figure 2.7: The three states of matter: liquid. Liquid: a form of matter that flows, has constant volume and takes the shape of its container

Figure 2.7: The three states of matter: gas. Gas: a state of matter that takes the shape and volume of its container Vapor: the gaseous state of a substance

Copper Phases - Solid

Copper Phases - Liquid

Copper Phases – Vapor (gas)

Phase Differences Solid Solid – definite volume and shape; particles packed in fixed positions. Liquid Liquid – definite volume but indefinite shape; particles close together but not in fixed positions Gas Gas – neither definite volume nor definite shape; particles are at great distances from one another Plasma – high temperature, ionized phase of matter as found on the sun.

Physical Changes/Properties Physical change: A type of change that alters the physical properties of a substance but does not change its composition Physical property: A characteristic that can be observed or measured without changing the sample’s composition (density, color, odor, hardness, melting point, boiling point) –Extensive: dependent of the amount of substance present (mass, length, volume) –Intensive: independent of the amount of substance present (density)

Figure 2.15: No chemical change occurs when salt water is distilled.

Chemical Change A change in which one or more substances are converted into different substances. Heat and light are often evidence of a chemical change. Chemical Property The ability of a substance to combine with or change into one or more other substances

Figure 2.8: Electrolysis, the decomposition of water by an electric current, is a chemical process.

Law of Conservation of Mass mass reactants = mass products States that: mass is neither created nor destroyed during a chemical reaction

Classification of Matter

Separation of a Mixture The constituents of the mixture retain their identity and may be separated by physical means.

Figure 2.16: Filtration separates a liquid from a solid.

Figure 2.17: Separation of a sand- saltwater mixture.

Separation of a Mixture Distillation

Separation of a Mixture The components of dyes such as ink may be separated by paper chromatography.

Figure 2.10: Twenty-four-karat gold is an element. Eighteen-karat gold is an alloy. Fourteen-karat gold is an alloy.

Figure 2.9: The composition of air.

Chart examining each substance of air.

Law of Definite Proportions States that: A compound is always composed of the same elements in the same proportion by mass no matter how large or small the sample -the mass of the compound is equal to the sum of the masses in the elements that make it up -can be expressed as % mass % mass = mass of element x 100 mass of compound

Law of Multiple Proportions States that: compounds can be composed of the same elements in different ratios (H 2 O, H 2 O 2 ) or (CO and CO 2 ) - -end Ch. 3

Figure 2.5: The three forms of the element carbon: Diamond.

Figure 2.5: The three forms of the element carbon: Graphite.

Copyright © by Houghton Mifflin Company Figure 2.5: The three forms of the element carbon: Buckminsterfullerene.

Figure 2.11: Representation of H 2 O molecules.