Chemistry

Chapter 1 Matter and Change

Chemistry is…

The study of the interactions of energy and matter

1.1 Areas of Chemistry

Physical chemistry—develop theories about why things occur, may develop mathematical models to explain in detailOrganic chemistry—specializes in carbon containing compoundsBiochemistry—chemistry of living things; biological processes like photosynthesis, etc.Analytical chemistry—looks at the chemical make-up of materials; very mathematical and repetitiousInorganic chemistry—chemistry of compounds not containing carbon

1.2 Chemistry Far & Wide

Materials– Bronze, Ceramics, Plastics

Energy– Two ways to provide energy – conservation and

increased production– Non-renewable – fossil fuels– Renewable – Solar, wind, hydroelectric, hydrogen– Nuclear

1.2 Chemistry Far & Wide

Medicine and Biotechnology– Production and development of pharmaceuticals– Production and development of materials used to

provide synthetic replacement of body parts

Agriculture– Increasing world food supply

1.2 Chemistry Far & Wide

Astronomy and Space Exploration– Analysis of materials brought from other celestial

bodies provides useful geological information

1.3 Scientific Method

The scientific method is used to solve problemsSTEP ONE: what is your problem?STEP TWO: form a hypothesis (prediction of what you think the answer to your problem may be)STEP THREE: develop a method to test your ideasSTEP FOUR: run your experiment to gather data that will either confirm or refute your original hypothesis. STEP FIVE: draw conclusions about your experiment

Application of scientific method

Step 1:   State the problem You cannot solve a problem until you know exactly what it is. My Problem is - "I need a date for Friday Night". Step 2:   Research the problem What will it take to solve my problem? What do I know, and need to know, about my problem? To solve my problem, "I need someone to take out Friday Night". – Who can I take?

Examine the possibilities. Eliminate poor choices. Consider likely choices.

Step 3:   Form a hypothesis

A possible solution to my problem. The simplest solution is often the best solution! "My date will be ( Name )".

Step 4:   Test the problem

Perform an experiment to see if your hypothesis works. "Ask ( Name ) for a date Friday Night".

Step 5:   Draw conclusions Data are the results of an experiment. In its simplest form, there are only two possible conclusions: Conclusion 1   If your hypothesis was correct, you now have a date for Friday.

PROBLEM SOLVED!Conclusion 2   If your hypothesis was incorrect, the experiment failed.

DON'T GIVE UP! DO MORE RESEARCH!- What was wrong with your original hypothesis? - Did you make a poor selection? - Was your experiment flawed? - Form another hypothesis based on additional research. - Test the new hypothesis.

THE SCIENTIFIC METHOD

Scientific MethodObservations Hypothesis Experiments Theory Experiments Observations Experiments LawScientific Law - Concise statement that summarizes the results of many experiments and observations.

1.8 Chemical Symbols

On the Periodic Table, elements are shown with their chemical symbolMany symbols are derived from Latin names, therefore their symbols do not directly relate to their current name (sodium, symbol Na from the Latin name natrium)Remember, capitalize the first letter, second letter is lowercase!!

1.9 Chemical Reactions

Type of change in which new substances are formed and are different in chemical arrangementBeginning substance(s) called REACTANTSEnd substance(s) called PRODUCTSFormat for chemical reactions

NH4NO3 N2 + H2O + O2

reactant products

2.1 MatterSolids – definite shape and volume.Liquids – flows, fixed volume, takes the shape of its containerGas – Takes both the shape and volume of its containerGas vs. Vapor – Gases exist in the gaseous state at room temperature. Vapors exist as solids or liquids at room temperature.What about toothpaste? Hair gel?– These are called thixotropic substances

2.1 Properties of Matter

Matter—all things that have mass and take up space (air, pencil, dog)Substance—pure water, table salt, wool—specific things (types of matter) with definite composition (not river water, books, people)Physical properties—can be observed without changing the substance’s chemical arrangement– Color, odor, mass, density, boiling or melting point

Chemical properties—observed when substance undergoes a chemical change– Flammable, soluble in oil, reactive with HCl

2.1 Physical ChangeDoes not change the CHEMICAL COMPOSITION of the substance– Melt– Boil– Freeze– Tear– Crush– Dissolve in water

These are often reversible processes

2.2 Mixtures(blend of 2 or more substances)

Heterogeneous mixturesNot “uniform” in compositionIndividual components are easily identified Can physically separate– Trail mix– Students in this class– Blood

Homogeneous mixturesSame throughout sampleConsists of a single phaseMilkLemonade (pulp free)Brass (alloy)PG 38

2.2 Mixtures

Solutions are homogeneous mixtures. Solutions can be gases, liquids, or solids.A phase is any part of a system with uniform composition.Distillation is a process in which a liquid – usually containing impurities – is boiled. The vapor is condensed and collected.

2.3 Elements and Compounds

Element—nitrogen (N), oxygen (O), mercury (Hg)– Particles of an element are called ATOMS or…– diatomic elements (7 of them: Br I N Cl H O F) exist as

MOLECULES…two atoms are bonded together

Compound—when two or more atoms of different elements are chemically bonded together– Particles of a compound are called molecules (if

nonmetals) or formula units (metal/nonmetal combo)

2.4 Chemical Reactions

Indicators of Chemical Reactions– Burning– Rotting– Rusting– Decomposing– Fermenting– Exploding– Corroding

2.4 Conservation of Mass

In all physical and chemical changes, matter is never created nor destroyed.This is a LAW! (It summarizes many, many experiments in a statement; it is unlike a theory which is more descriptive.)Explain: If a sample of wood is less in mass after being burned, has the Law of Conservation of Mass been violated?