Unit 1 Chapters 1-4

Introduction to Chemistry Chapter 1 Introduction to Chemistry

What is Chemistry & Why should we study it? Chemistry - The study of the structure, properties, and composition of substances, and the changes the substances undergo Reasons to study Materials are made using chemistry Energy Where will it come from? Medicine & Biotechnology Agriculture Environment Astronomy & Space Exploration

Branches of Chemistry Organic Chemistry Inorganic Chemistry The study of compounds that contain carbon. Inorganic Chemistry The study of substances that do not contain carbon. Analytical Chemistry The study of the composition of substances. Physical Chemistry The study of the behavior of chemicals. Biochemistry The study of the composition and changes in composition of living organisms.

Scientific Method

Scientific Method Continued Observation An act of seeing some fact or occurrence; often involves a measurement Hypothesis A descriptive model used to explain observations. Experiment A carefully controlled, repeatable procedure for gathering data to test a hypothesis. Theory A thoroughly tested model that explains why experiments give certain results. Scientific Law A concise statement that summarizes the result of a broad variety of observations and experiments

Chapter 2 Matter and Change

Matter A formal definition of matter is anything that takes up space and has mass.

States of Matter Solid - Matter that has definite shape and volume. Liquid - A form of matter that flows, has a fixed volume, and takes the shape of its container. Gas - Matter that has no definite shape or volume; it adopts the shape and volume of its container.

Classifications of matter Substance: - uniform and definite compostion or pure Element: - simplest form of matter made of atoms Compounds: - two or more elements chemically combined made of molecules or formula units

Mixtures A mixture is a combination of two or more substances in which the basic identity of each substance is not changed. Homogeneous mixture – A mixture that is completely uniform in its composition; its components are not distinguishable. Heterogeneous mixture – A mixture that is not uniform in its composition; its components are readily distinguishable.

Flow Chart for Classifying Substances

Separating Mixtures Filtration Settling Distillation Evaporation Crystallization Chromatography

Properties of Matter The properties of matter describe the characteristics and behavior of matter, including the changes that matter undergoes.

Physical Properties Physical properties: A quantity of a substance that can be observed or measured without changing the substances chemical composition. - Color Temperature solubility, melting point, boiling point, density,electrical conductivity and physical state (solid, liquid, or gas).

Physical Change A physical change occurs when there is an alteration of a substance that does not affect its chemical composition. Ripping paper Boiling water Melting ice

Chemical Properties The ability of a substance to undergo chemical reactions and form new substances. Rust Tarnish Burn Oxidize

Chemical Change Formation of new chemicals or substances is the only true way. Visual signs that could indicate chemical change. Production of heat Evolution of Gas Emission of Light Color Change Formation of a precipitate (Solid)

Scientific Measurement Chapter 3 Scientific Measurement

Types of Measurement Qualitative measurement – A measurement that gives descriptive, nonnumeric results Size Shape Color Quantitative measurement – A measurement that gives definite, usually numeric results Weight Length Time

Uncertainty in Measurements Accuracy – The closeness of a measurement to the true value of what is being measured. Precision – The reproducibility, under the same conditions, of a measurement Accurate but not precise Precise but not accurate Accurate and Precise

Calculation of Percent Error Percent error – The percent that a measured value differs from the accepted value. Accepted Value – A quantity used by general agreement of the scientific community Experimental Value - Measured in Lab % Error = |Accepted Value - Experimental Value| * 100% Accepted Value

International System of Units SI - le Systéme International d’Units Revised version of the metric system

Units of measurement Metric System (pg. 64) a. 1000________ = 1 kilo________ b.  100 centi________ = 1 ________ c. 1000 milli________ = 1 ________ d.  1,000,000 micro _____ = 1 _____ e. 1,000,000,000 nano____ = 1 _____

Scientific Notation Used to express very large or very small numbers Written in the form N x 10n where N is greater than 1 and less than 10 and n is an integer. If you move the decimal to the left, the power of 10 is positive and the actual number is very large. If you move the decimal to the right, the power of 10 is negative and the actual number is very small.

Is there a difference between mass and weight? YES!!!! Mass - how much matter something has Weight - mass with the affects of gravity If you go to the moon do you have the same mass as on earth? How about weight?

Temperature The measure of the kinetic energy of the molecules in a substance Two main scales - Celsius Scale - 0oC freezing point of water 100oC boiling point of water Kelvin Scale - Freezing point of water is 273 K boiling point of water is 373 K Absolute Zero - all motion and movement stops. Converting between the two is easy! K = oC + 273 oC = K -273

How to measure correctly - Determine the smallest interval on the measuring device: scale and units. Estimate one digit more then the smallest unit of the scale. Example: ruler A ruler B ruler C

Significant Figures In a measurement, they include all of the digits that are known plus one last estimated digit.

Rules: ) Every nonzero digit reported in a measurement is assumed to be significant. Examples: 24.7 meters and 358 grams all have 3 significant figures. ) Zeros appearing between nonzero digits are significant. Examples: 308 cm, 5.03 liters & 0.303 grams All have 3 significant figures. ) Zeros at the end of a number and to the right of a decimal point are significant. Examples: 27.50 meters & 1.000 liters both have 4 sig. figs.

Rules Continued…. 4) Zeros in front of nonzero digits are not significant Examples: 0.00017 meters & 0.013 grams Both have two significant figures. Zeros at the end of a measurement and to the left of a decimal vary. Examples: 1200 has two sig. figs 1200. Has four sig. Figs.

The last Rule: ) There are two situations in which measurements have an unlimited number of significant figures. Counting - If you count then you have unlimited sig. figs as no measuring device was used. Exactly defined quantities 60 minutes = 1 hour (both numbers have unlimited sig. figs.)

Calculations with Significant Figures Rounding - less than 5, drop remaining digits greater than 5 & equal to 5, round up Example: 3.75 grams Round to 2 sig. figs. 3.75 greater/= to 5 round up Answer = 3.8 grams Addition & Subtraction 1) Add the numbers together ) Round to the least precise measurement (digit).

Addition Example: 90. ml + 15.5 ml __________ 105.5 ml Answer: What digit do both measurement go to? The ones: therefore 106 ml is correct.

Calculations with Significant Figures Continued... Multiplication & Division ) Count the number of significant figures for each number. ) Do the multiplication or division ) Round answer to the least number of significant figures Example: 3.2 cm x 5.38 cm x 3.020 cm = Calculator Answer = 51.99232 cm3 Correct Answer = 52 cm3

The ratio of mass to volume density = Mass Volume

Problem Solving in Chemistry Chapter 4 Problem Solving in Chemistry

Dimensional Analysis Process of changing units of a measure value

To solve dimensional analysis problems, use A.C. E. A.C.E. - five step problem solving Analyze 1. identify knowns 2. identify unknowns 3. Plan of attack: pick conversions to get from known to unknown Calculate 4. Set up problem and show unit cancellation Evaluate 5. Answer with label and significant figures Does the answer make sense?

Conversion Factors The measurement in the numerator is equivalent to the measurement in the denominator. 1 meter = 100 centimeters 1 meter = 1 or 100 centimeters =1 100 centimeters 1 meter