1. Chemical Foundations

2. Why is Chemistry Important?
New materials
New pharmaceuticals
New energy sources
Food supplies
Help the environment
Can you think of others?

3. What is Chemistry? Biology Physics Chemistry Earth Sciences
Chemistry is a central science that deals with the materials of the universe and the changes they undergo.
Physics
Chemistry
Biology
Earth Sciences

4. The Scientific Method Observation Summary of What Happens Hypothesis
(measurable)
Ex: law of conservation of mass
Observation
Hypothesis
Experiment
Theory (model)
Law
Theory
Modified
as needed
Prediction
Model which attempts to explain why it happens
Atomic Theory
Experiment

5. NGSS: A modified way of thinking for scientists
Asking questions (for science) and defining problems (for engineering)
Developing useful models
Planning and carrying out investigations
Analyzing and interpreting data
Using mathematics and computations thinking
Constructing explanations (for science) and designing solutions (engineering)
Engaging in argument from evidence
Obtaining, evaluating, and communicating information
Focus on application and practice

6. Types of observations Qualitative Quantitative Overview:
Deals with descriptions
Data can be observed but not measured
Colors, textures, smells etc.
Qualitative -----Quality
Deals with numbers
Data which can be measured
Length, Height, volume, weight, speed, time, temp
Quantitative-----Quantity
Example: Oil Painting
Blue & green paint
Gold frame
Masterful brush strokes
10” x 14”
surface area 140 in2
Weight: 8.5 pounds

7. Qualitative observations

8. Measurements in chemistry
Quantitative observation.
Has 2 parts – number and unit.
Number tells comparison.
Unit tells scale.

9. Measurements in chemistry (con’t)
Scientific Notation
Technique used to express very large or very small numbers.
Move the decimal so that one non zero integer is to left
If you moved to the left then the exponent is positive (number is big)
If you moved to the right then the exponent is negative (number is small)

10. Units of Measurement SI System (Système International d'Unités)
units derived from the metric system.
Physical Quantity
Name of Unit
Abbreviation
Mass
Kilogram kg
Length
Meter m
Time
Second s
Temperature
Kelvin k
Electric Current
Ampere A
Amount of substance
Mole
mol
Luminous intensity
Candela cd

11. Units of Measurement
Prefixes are used to change the size of the unit.

12. Volume Measure of the amount of 3-D space occupied by a substance.
SI unit = cubic meter (m3)
Commonly measure solid volume in cm3.
1 mL = 1 cm3
1 L = 1 dm3

13. Precision and Accuracy
Accuracy: agreement of a particular value with the accepted value.
Precision: agreement among several measurements of the same quantity (reproducibility).
Using an instrument to measure an object
Pipette analogy – you have to calibrate the instrument.
Accuracy is the ACTUAL number you want
Precision is reproducible.

14. Uncertainty in Measurement (2.4)
The length of the pin occurs at about 2.85 cm.
Certain digits: 2.8 5
Uncertain digit: 2.8 5

15. Uncertainty in Measurement (2.4)
Volume of a container
Certain digits: ml
Uncertain digits: ml

16. Significant Figures & Calculations (2.5)
Rules for counting Significant Figures:
1. Nonzero integers always count!
2. Zeroes (3 classes):
0.0065
Leading!
a. Leading zeroes do not count (place holders)
b. Captive zeroes do count
4005
Captive!
c. Trailing zeroes are if there is a decimal point
65.00
Trailing!
3. Exact numbers (counting or from definitions)
9 pencils, 24 students etc.

17. Significant Figures & Calculations (2.5)
Rules for Significant Figures in calculations:
1. For multiplication or division: the answer is the same as the LEAST precise number in the calculation.
67.64 grams x 43 grams =
grams2
4 Sig Figs
2 Sig Figs
Answer must have 2 Sig Figs
Count from the left starting with the first Integer
grams2
Use the first number past to round (up if 5 or more)
Answer = 2900 grams2

18. Significant Figures & Calculations (2.5)
Rules for Significant Figures in calculations:
2. For addition or subtraction: the answer has the same number of decimal places as the least precise measurement in the calculation.
3 decimals
The answer MUST have only 2 decimal places!
grams
grams
6.175 grams
Count the two then use the one right after to round. (up if 5 or more)
2 decimals
grams
3 decimals
grams
Answer = grams

19. Significant Figures & Calculations (2.5)
Rules for Significant Figures in calculations:
3. Rounding: DO NOT round until all calculations are completed. Use only the first number to the right of the last significant figure.

20. Atlantic/ Pacific Rule