What is Chemistry? What is Matter? What is Mass? the study of matter and the changes that it undergoes. What is Matter? anything that has mass and takes up space What is Mass? a measurement of the amount of matter in an object

Mass verses Weight They are related, but what’s the difference? Mass is universal, weight depends on gravity Weight = mass times the gravitational pull

Branches of Chemistry Organic Inorganic Analytical Physical Biochemical

Organic Area of Emphasis Most carbon-containing chemicals Examples: Pharmaceuticals Plastics

Inorganic Area of Emphasis In general, matter that does not contain carbon Examples: Minerals Metals and nonmetals Semi-conductors

Analytical Area of Emphasis Components and composition of substances Examples: Food Nutrients Quality Control

Physical Area of Emphasis The behavior and changes of matter and the related energy changes Examples: Reaction Rates Reaction Mechanisms

Biochemical Area of Emphasis Matter and processes of living organisms Examples: Metabolism Fermentation

Next, the Scientific Method

Why do we have the scientific method? Gives us logical steps to follow to assist us in answering a question.

What are the “steps”? Develop a question Conduct background research Form a hypothesis Test with an experiment Make observations and collect data Analyze the results Draw conclusions Report results and test again

Step 1: Ask a Question Scientists ask questions based on observations from their surroundings

Step 2: Form a Hypothesis Take an educated guess about what you think the answer is to your question

Step 2: Form a Hypothesis Hypothesis: an educated guess or prediction; an “if, then” statement If ____independent variable______ then__dependent variable_______

Example: Independent Variable: I feed my cat a lot of food she will get fat If ___________________________ then _________________________

Try to use INCREASE and DECREASE in your hypothesis! Remember Try to use INCREASE and DECREASE in your hypothesis! Ex. IF I increase the amount of food I give my cat, THEN she will increase her weight

Step 3: Test your hypothesis Set up an experiment to test your question

Types of Variables There are 2 main types of variables: Independent Variable: The variable that is changed by the scientist; the ‘I control’ variable Dependent Variable: The variable that might change because of what the scientist changes – what is being measured

Remember! Your hypothesis can TELL you what your variables are! Ex. If I drink Mountain Dew before bed, then I will not sleep very much. IV: Drinking Mountain Dew DV: the amount of sleep

Use this hypothesis to identify the variables: Practice Use this hypothesis to identify the variables: If I leave all the lights on all day, then my electric bill will be expensive IV: ______________________ DV: ______________________

If I brush my cat more, then there will be less fur on my furniture IV: ______________________ DV: ______________________

Now read the following experiment and identify the independent and dependent variables Elizabeth wanted to test if temperature affected how fast milk goes bad and curdles. She left milk in a room temperature closet, a fridge, and a oven that was turned on low heat. She then measured how rotten the milk was after 10 days. IV: ____________________________________ DV: ____________________________________

Step 4: Analyze Your Results Look at your results and decide what they tell you about your question

Step 5: Form a Conclusion Decide what the answer to your question is and ask: Was my hypothesis right or wrong? Do I need to do the experiment again to find out more?

Parts of an experiment

Independent Variable Part of the experiment that the scientist changes What is being tested There is only one independent variable at a time. What I change

Dependent Variable Part of the experiment that changes because of the independent variable

Part of the experiment that does not receive the independent variable Control Part of the experiment that does not receive the independent variable

Constants Part of the experiment that remain the same for every part of the experiment

Types of Data Quantitative Data that is numerical in nature Qualitative Data that is descriptive in nature

An example experiment A person wants to test whether music can help make plants grow. The person plants several seeds from the same batch into identical flower pots with identical potting soil, watering schedule and light supply. One flower pot is isolated from the sound supply, while the other pots are subjected to various types of music. After 1 month, the “healthiness” of each plant is measured.