Chapter 1 Introduction to Chemistry
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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?
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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?
inorganic
Carbon
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
IV
DV
Constants
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!)