1. 1 Chemistry Chapter 1 Scientific method and Data management Chemistry- Matter and Change Glencoe

2. 2 The Scientific Method Is a systematic way of gathering evidence to support ideas and theories that help explain the natural world around us. Steps to the scientific method  State the Problem  Do some research and form a hypothesis A Hypothesis is a testable prediction based on research and observations. It is what you think the answer to the problem is. A good way of writing a hypothesis is: If…(a cause (independent variable) )…then…(an effect (dependent variable) ).

3. 3 An experiment should have these three things to be a proper experiment  Variables are things that change. There are always two; The independent variable. Sometimes called the manipulated variable. The experimenter chooses one thing to do differently in the experiment. The dependent variable. Sometimes called the measured or responding variable. This is the data that is being gathered or recorded. 3.Design and conduct an experiment.

4. 4 II.Constants are all other things in the experiment that are kept the same all the time. III.A control is a standard for comparison. It is like a base line or the data at time zero. You will compare the data you gathered to it to see how much the dependent variable changed.

5. 5 4.Analyze the Data This includes making graphs and/or calculations. Look for trends in the data.  Parts of a proper graph: (more info to come) Use graph paper and a ruler Title: Dependent vs. Independent Labels including units: independent – x axis, dependent – y axis Appropriate scale: Data range/number of lines, round up to a counting number Smooth line or curve

6. 6 5.Draw a conclusion A conclusion is a 5 sentence paragraph that summarizes your investigation.  Restates your hypothesis  Briefly describe your experiment.  What was the data you collected. Give examples of your data as evidence.  What was the trend you found in the data or what does the data mean.  Did the data trend support or reject your hypothesis.

7. 7 A theory is an explanation that has been supported by many, many experiments. It is the most logical explanation of why things work they way they do based on evidence gathered by experimentation. Scientific Law is a relationship in nature that is supported by many experiments. It is a rule that describes, but doesn’t explain, a pattern in nature and predicts what will happen under special conditions. It is often described with a mathematical equation. Theory & Law

8. 8 Report your results You will want to put your research out for peer review and/or publish your findings for your peers to evaluate.

9. 9 Data Table Format The proper format for a data table is:  Label your independent variable and unit in the first/left-most column  Label your dependent variable and unit in the next/right-most column  REVIEW: Independent Variable  The thing that is changed by the experimenter Dependent Variable  The thing that is measured in the experiment Organizing and Graphing Data

10. 10 Titling a Graph A title for a graph should describe what the experiment was comparing For pie graphs:  Titles should name the quantity or thing being divided Student Hair Color For line and bar graphs:  Titles should list the dependent variable vs. the independent variable Temperature vs. Time All titles are placed at the TOP of the graph

11. 11 Creating Line & Bar Graphs Line and bar graphs must: use graph paper if not constructed on a computer use even graduations or scale with even increasing or decreasing increments along the axis - to determine scale for x and y axis, divide range of data (data range is highest value – lowest value) by the number of lines on the axis. Then round the number up to a good counting number like.1,.2,.5, 1, 2, 5, 10, 20, 50… Start your scale near the lowest number.

12. 12 Calculating the Scale on a Graph For example:  The left hand column is the independent variable. The data range should subtract the high data point from the low data point. Data range:  Then count the number of lines on the axis you will be putting the scale on.  For example: Speed (m/s) Water Temperatur e (°C) 1725 1428 1131 834 537 Then divide the range by the number of lines You need to round that number up to one that is easy to count by like 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 Start your scale near the lowest number. 17-5=12 22 12 = 0.54 22 = 1.0

13. 13 The Metric System This system is based on powers of 10. It consists of a base unit which is changed by powers of ten when a prefix is added Metric Conversion scale Great Mighty King Henry Died monday drinking chocolate milk maybe no one paid attention Giga __ __ Mega__ __ Kilo Hecto Deka base unit deci centi milli__ __micro__ __nano__ __pico (meter) G- M- K- H- D- or dk- m,g,L,s d- c- m- µ- n- p- 10 9 10 6 1000 100 10 1 0.1 0.01 0.001 10 -6 10 -9 10 -12

14. 14 SI System Because units are combined all the time in math equations they often become very large and complex. They are called derived units and consist of multiple base units. Scientists tend to abbreviate them. Example: The equation for potential energy is E P = mgh The unit for this using all base units is Kg m 2 /s 2 The abbreviated version of this unit is J for Joule Without standardizing the base units, scientists would never know which mass, distance and time unit was imbedded in the abbreviated unit Joule.

15. 15 7 Standard Base Units QuantityBase unit TimeSeconds (s) Lengthmeter (m) MassKilogram (Kg) TemperatureKelvin (K) Amount of a specific substance mole (mol) Electric current ampere (A) Luminous intensity candela (cd)

16. 16 Mass: The amount of matter (atoms) an object has. Unit: grams or kilograms Volume: The amount of space an object takes up. Unit: milliliters or cm 3 Density : A relationship between the mass and volume of an object. Or; the amount of matter per volume.