Chapter 1 Introduction to Chemistry

Chapter 1 Introduction to Chemistry ? Where is it? When an object burns, the quantity of ashes that remain is smaller than the original object that...
Author: Claude Goodman
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Chapter 1 Introduction to Chemistry


Where is it? When an object burns, the quantity of ashes that remain is smaller than the original object that was burned. What happened to the rest of the object?

? ?

How do you account for the change in mass?

Where is the matter that appears to have been lost?

Chapter 1 Introduction to Chemistry

I.  The Story of Two Chemicals? (pages 1-6) Two unrelated discoveries that form the basis of one of the most important environmental issues of our time.

Chapter 1 Introduction to Chemistry How are these people protecting themselves from the sun?

Why is this protection necessary?

Chapter 1 Introduction to Chemistry

? What is Ozone depletion? A. The Ozone Layer ü  Ozone protects us from UV radiation ü  UV radiation can cause skin cancer ü  UV radiation is harmful to plants and the food chain

The Ozone Layer

Situation  and  structure

Chapter 1 Introduction to Chemistry

A. The Ozone Layer (Continued) ü  Where does the Ozone layer exist? Top of stratosphere ü  Where is the Ozone layer the thickest? At the Equator

Structure of the Atmosphere

•  Our  habitat  is  situated  in  the  Troposphere

General information about the Ozone layer

• The  Ozone  layer  is   located  in  the     stratosphere. • Ozone  serves  as  a   shield  against  UV-­‐‑B   and  UV-­‐‑C  radiation.   • This  is  the  only  way   life  on  earth,  as  we   know  it  today,  is   possible.  

Chapter 1 Introduction to Chemistry

A. The Ozone Layer (Continued) ü  How does O3 form?

Chapter 1 Introduction to Chemistry

B. Chlorofluorocarbons ü  CFC’s were used in refrigerators, plastic foams, and propellants in spray cans. ü  CFC’s are stable ü  As the concentration of CFC’s went up what happened to the O3 concentration? ü  Before we answer how this dilemma was solved we will study how chemists solve problems.

Chapter 1 Introduction to Chemistry

II. 1.2 Chemistry and Matter (pages 7-9) A.What is matter? Anything that has mass and occupies space. (has volume) Anything that is not Matter is Energy (Matter and Energy are Conserved) E = mc2

v Describing Matter a. Volume? Measures liquids, graduated cylinder

Can change with temperature, not reliable measurement

Do you think this astronaut weighs more, less, or the same on the Moon as he weighs on Earth?

v Describing Matter b. Weight?

Wt changes the farther you get from center of earth. Weight: measure of the force of gravity between two objects, not reliable. not reliable measurement.

Do you think this astronaut’s mass is more less, or the same on the Moon as it is on Earth?

v Describing Matter c. Mass?

Quantity of matter in an object, measure of how difficult it is to change an objects state of motion.

Not affected by temp, or location. Reliable measurement Use a balance to measure in grams or kilograms.

Who studies matter?



Behavior & change of matter and the related energy changes

Components & composition Biochem- matter & processes of living of substances organism (membrane)

III. Scientific Methods (pages 10-13)

What is wrong with this plant? How could you find out what is harming the plant?

III. Scientific Methods (pages 10-13)

A. Experimental Design (from the candle lab) 1.  How do you know what is burning and what is produced? 2.  What could we measure? a. Qualitative vs. quantitative observations and measurements Qualitative: descriptive observation-size, color, texture Quantitative: values and measures to a standard scale

b. Observation vs. inference

-can others verify your observations? An inference is an interpretation of the observation B. Formulate & Objectively Test Hypothesis

1.  Hypothesis Prediction a. def: educated guess, reasonable explanation for what you might observe b. Cause & effect (if/then statement) If more air is present, then a candle burns longer If more CFC’s are present, then there will be less O3 due to the interaction of of UV light.

c. Must be testable 2. Identifying the parts of the experiment a. how did you act on your candle? b. what did you purposefully change about the burning candle c. how did you determine a response? d. what remained the same in the burning candle? Action

Surround candle with air

Purposeful change

Response to change

Remained the same




Amount of air (levels, control)

Time candle burns before going out

Candle size, way to light it, envir. Cond.

C. Interpret results & revise the hypothesis if necessary D. State conclusions in a form that can be evaluated by others

Theories explain

1. Repeatable data can lead to a theory ***theory: broad generalization that is based on

observation, experimentation, known facts or phenomena & reasoning and supported over time

2. Models can be used (to make predictions) a.

Scale Models – globes, molecules, 3-D cities

2. Models can be used a. b. c.

Drawings, photos, charts

2. Models can be used c.

Graphs, computer simulations, mathematical models, formulas

We use models to Study Ozone Depletion Lets discuss the dilemma again

Consequences of Increased UVRadiation

1. Skin  cancer 2. Examples  of  other  illnesses 3.   Effects  on  nature

Damage caused by radiation

The  major  dangers  are  inflammatory   reactions  (sunburn)  and  damages  to  the   DNA  of  the  skin  cells,  which  can  lead  to   skin  cancer.   Benign  melanomata   and  malignant  melanomata   are  the  two  possible  types  of  skin   cancer  that  can  develop.  The   malignant  melanomata  are  also  called   black  skin  cancer.  

Benign  melanoma

Nodular  melanoma  (NM).

Malignant  melanoma

Superficial    spreading     melanoma  (SSM)

The malignant melanoma - black skin cancer Very  harmful  tumour   Place  of  development:  It  develops in the cells that give the skin its color (melanocytes)          Development:  On  normal  skin  or  allready  existing  cellular   nevus  (mole,  birthmark)   Starting  point:  Basal  cells;

At first it usually grows in a horizontal direction being rather superficial but depending on the type of melanoma it may start growing rapidly in a vertical direction at an early stage.

Examples for other illnesses §   Damage  to  the  eyes

§   General  weakening  of  the  immune  system

Effects on nature A  permanent  damage  to  the  environment  leaves  broad  features   on  plants:     §     Retrenchment  of  the  photosynthesis §     Shorter  sprouts §     Decrease  of  the  average  leaf  surface §     Alterations  within  the  plant  communities These  alterations  could  lead  to  extensive  crop  loss  and  to   changes  within  the  food  chain  or  could  contribute    to  forest   dieback.  

Effects on nature The  nutrient-­‐‑rich  phytoplankton  (e.g.  Algaes)   decline  in  the  seas.    As  the  process  develops  the  following   tendencies  become  apparent: §  Lack  of  food  for  fish  and  changes  in  the            composition  of  species   §  Loss  of  the  greatest  producer  of  oxygen,  as  well  as  less          conversion  of  CO2   §  Increase  of  the  greenhouse  effect

Click here for animation

A single CFC molecule can destroy 100,000 ozone molecules. CFCl3 + UV Light ==> CFCl2 + Cl Cl + O3 ==> ClO + O2 The free chlorine atom is then free to attack another ozone molecule

Cl + O3 ==> ClO + O2 and again ... Cl + O3 ==> ClO + O2 and again... for thousands of times.

Once CFC’s are released they take 2-5 years to reach stratosphere In 1978, the use of CFC propellants in spray cans was banned in the U.S. In 1987, the Montreal Protocol was signed and the signatory nations committed themselves to a reduction in the use of CFCs and other ozone-depleting substances. Since that time, the treaty has been amended to ban CFC production after 1995 in the developed countries, and later in developing countries. The answers, in order, are: yes and no. We can't make enough ozone to replace what's been destroyed, but provided that we stop producing ozone-depleting substances, natural ozone production reactions should return the ozone layer to normal levels by about 2050.

3. Laws – based on scientific facts, describes the behavior of the natural world Laws describe natural phenomena or relationships in nature

IV. Safety in the Laboratory (pages 14-16) (don’t forget to finish reading chapter one 1.4 Scientific Research!)