July 30, 2013


Turn in Homework: Science Autobiography

Write your name and period number

Define Chemistry using your own words

What is the SI base unit for the following measurements (Example: Volume = Liter (L))

Length = ___________

Mass = __________

Temperature = ___________

Time = __________


Brain Teaser

Notes:

Introduction to Chemistry

SI Units and Base Units

Significant Figures

Homework

Intro to Measurement Worksheet 1

Significant Figures Worksheet (?)

Unit 1 Objectives
Introduction to Chemistry

Define chemistry and matter

Units of measurement

SI Units

Base Units

Accuracy versus Precision

Uncertainty in Measurement

Significant Figures

Significant Figures in Calculations

Dimensional Analysis


Chemistry: The
Central Science
 Chemistry is the science that investigates and explains the structure and properties of matter.
 Seeks to explain the submicroscopic events that lead to macroscopic observations

Branch
Organic chemistry
Inorganic chemistry
Physical chemistry
Analytical chemistry
Biochemistry
Area of Emphasis Examples most carbon-containing chemicals pharmaceuticals, plastics in general, matter that does not contain carbon minerals, metals and nonmetals, semiconductors the behavior and changes of matter and the related energy changes reaction rates, reaction mechanisms components and composition of substances matter and processes of living organisms food nutrients, quality control metabolism, fermentation

SI Units ( Le Systéme Internationale)
 Scientists need to report data that can be reproduced by other scientists. They need standard units of measurement.
• A base unit is a defined unit in a system of measurement
•There are seven base units in SI.


Handouts

Kilo, centi, milli


Significant
Figures
Digits in a measurement that have meaning relative to the equipment being used


Place What is the increment on the equipment?
What you know for sure.


Digits with meaning
Digits that can be known precisely plus a last digit that must be estimated.


Uncertainty: Limit of precision of the reading (based on ability to guess the final digit).

Existed in measured quantities versus counted quantities

Refer to Example (2 rulers)

 http://www.funbrain.com/measure/

What are the units?

 http://www.uwplatt.edu/chemep/chem/chemscape
/labdocs/catofp/measurea/volume/gradcyl/gradc yl.htm

What are the units?


What do you notice?
Depends on type of equipment being used.
Depends on size of equipment used.

Things to consider
 What do significant figures tell you about the measurement on the equipment?
 If you wanted to measure the mass of a whale, what scale would you want to use? Would it matter if you know its mass accurately to 1 gram?
 If you wanted to measure the mass a grain of sand , what scale would you want to use? Would it matter if you know its mass accurately to 1 gram?


Raw Data Rules

How do you know how many sig figs?
1.
2.
3.
4.
5.
All digits 1-9 are significant.
Zeros between significant digits are always significant.
Trailing 0’s are significant only if the number contains a decimal point
Zeros in the beginning of a number with a decimal point are not significant.
Zeros following a significant number with a decimal are significant.


Pacific to Atlantic
Rule
Pacific = Decimal Present
Start from the Pacific (left hand side), every digit beginning with the first 1-9 integer is significant

Examples
20.0 = 3 sig digits
0.00320400 = 6 sig digits
1000. = 4 sig digits


Atlantic Rule to
Pacific
Atlantic = Decimal Absent
Start from the Atlantic (right hand side), every digit beginning with the first 1-9 integer is significant

Examples
100020 = 5 sig digits
1000 = 1 sig digits

2.
3.

1.
4.
How many significant figures are in
400.0
4000
4004
0.004









Determine the number of significant figures in the following:
1005000
1.005
0.000125
1000.
0.02002
2002
200.200

Determine the number of significant figures in:

72.3 g


60.5 g
6.20 g





0.0253 g
4320 g
0.00040230 g
4.05 x 10 5 g
4500. g

1.
2.
Measurement Worksheet 1
Significant Figures 1 Worksheet

Why do we use the metric system?

Advantages

Simple to use

Easy to convert from one unit to another
 Dimensional Analysis

Universal – used worldwide

By all scientists to communicate

By all industrialized nations

Except United States

U.S. loses billions of dollars in trade


Question:

What is the difference between mass and volume?

Introduction to Chemistry
• Chemistry: The
Central Science
• A more formal definition of
Matter is anything that takes up space and has mass
•
Mass is the measure of the amount of matter that an object contains
•
Volume is the amount of space an object takes up.


Refer to the two identical spherical objects below
Bowling Ball
Volley Ball


Which of the following weighs more?

A ton of feathers?

A ton of bricks?

SI Units ( Le Systéme Internationale)
 Scientists need to report data that can be reproduced by other scientists. They need standard units of measurement.
• A base unit is a defined unit in a system of measurement
•There are seven base units in SI.

Why do we use the metric system?

Advantages

Simple to use

Easy to convert from one unit to another
 Dimensional Analysis

Universal – used worldwide

By all scientists to communicate

By all industrialized nations

Except United States

U.S. loses billions of dollars in trade


Convert 3400 milliliters to liters

44 centimeters to meters

277 kilograms to grams


What is the difference between accuracy and precision?


Precision: is a measure of how closely an individual measurements agree with one another

Can be precise but inaccurate

Accuracy: refers to how closely individual measurements agree with the correct, or “true” value

Examples using the dartboard

An archery target illustrates the difference between accuracy and precision.

Accuracy and Precision
Measurements


Uncertainty: Limit of precision of the reading (based on ability to guess the final digit).

Existed in measured quantities versus counted quantities

Which electronic balance below allows you to obtain a more precise measurement? Why?
A B

 http://www.wisconline.com/objects/index_tj.asp?objID=GCH202

What are the units?

 http://www.funbrain.com/measure/

What are the units?

 http://www.uwplatt.edu/chemep/chem/chemscape
/labdocs/catofp/measurea/volume/gradcyl/gradc yl.htm

What are the units?


Objectives

Measure each physical quantity to the maximum accuracy allowed by the appropriate instrument.

Record measurements and calculations with the appropriate units from the international system of units (SI.)


Set up assignment

Title, Name, Chemistry, Period, Date

Station Rotation

10 Station

3-4 minutes at each station

Refer to Handout

Do NOT remove any items from the station

Clean Up and Restore each station before switching


Homework

“Is it worth the risk?” worksheet

Sign Lab Safety Contract

Study for Lab Safety Test (Monday)

Get Supplies for Chemistry


Reflect on your learning during the lab activity

Concepts learned?

“Ah-ha” moments?

Questions?





All zeros count except placeholder zeros

These are the ones that disappear when you write the number in scientific notation.
Zeros between nonzero digits are always significant

E.g. 1005 kg (4 sig. fig) and 1.03 (3 sig. fig)
Zeros at the beginning of a number are never significant

E.g. 0.02 (1 sig. fig) and 0.0026 (2 sig. fig)
Zeros at the end of a number are significant if the number contains a decimal point

0.0200g (3 sig. fig), 3.0 cm (2 sig. fig), 5000 (1 sig. fig)

Rules for recognizing significant figures
• Non-zero numbers are always significant.
• Zeros between non-zero numbers are always significant.
• All final zeros to the right of the decimal place are significant.
• Zeros that act as placeholders are not significant.
• Counting numbers and defined constants have an infinite number of significant figures.









Determine the number of significant figures in the following:
1005000
1.005
0.000125
1000.
0.02002
2002
200.200

Determine the number of significant figures in:

72.3 g


60.5 g
6.20 g





0.0253 g
4320 g
0.00040230 g
4.05 x 10^5 g
4500. g


Reflect on your learning today


Measurement Worksheet 2

Science Safety Test

Wednesday = TOMORROW

Element Quiz

Thurs/Fri

Lab Notebook

Quadrille Lab Notebook (Graphing paper) OR

Carbonless Copy Lab Notebook


Lab Safety

Measurements

SI units

Significant Figures, Uncertainty

Accuracy and Precision

Understanding Equipments

Dimensional Analysis