SI - (AKA International System of Units or S.I.) is a measuring system based on units of 10.
Math – the language of scienceUnits in the S.I. are: meter (m), which is used for measuring
length. liter (l), which is used to measure volume.
* gram (g), which is used to measure mass.
SI – International System of Units
Kilo (k)
Hecto (h)
Deka (de) or deca (da)
Base Unit (m, l, or g)
Deci (d)
Centi (c)
Milli (m)
1000
100
10
1 0.1
0.01
.001
1000/1 100/1 10/1
1
1/10
1/100 1/1000
SI (metric) prefixes
STOP DO NOT WRITE UNTIL I TELL YOU TO The three prefixes that we will use the
most are:◦ kilo◦ centi◦ milli
kilo hecto deca
Base Unitsmete
rgramliter
deci centi milli
These prefixes are based on powers of 10. What does this mean?◦From each prefix every “step” is
either: 10 times larger
or 10 times smaller
◦For example Centimeters are 10 times larger than
millimeters 1 centimeter = 10 millimeters kilo hecto deca
Base Unitsmetergramliter
deci centi milli
An easy way to move within the metric system is by moving the decimal point one place for each “step” desired (swoop method)Example: change meters to centimeters
1 meter = 10 decimeters = 100 centimetersor1.00 meter = 10.0 decimeters = 100. centimeters
kilo hecto decameterliter
gramdeci centi milli
If you move to the left in the diagram, move the decimal to the left
If you move to the right in the diagram, move the decimal to the right
kilo hecto decameterliter
gramdeci centi milli
YES WRITE THESE NOTES: Summary
◦ Base units in the SI (metric system) are meter, liter, gram
◦ Metric system is based on powers of 10◦ For conversions within the SI, each “step” is 1
decimal place to the right or left◦ Using the diagram below, converting to the right,
moves the decimal to the right and vice versa
kilo hecto deca
BASE UNITSmeterliter
gram
deci centi milli
Practice problems:
Base SI UnitsQuantity Unit Symbol
Length meter mMass kilogram kgTemperature kelvin KTime second sAmount of Substance
mole mol
Luminous Intensity
candela cd
Electric Current ampere a
Other - SI Unit PrefixesName Symbolgiga- G 109
mega- M 106
kilo- k 103
deci- d 10-1
centi- c 10-2
milli- m 10-3
micro- μ 10-6
nano- n 10-9
pico- p 10-12
Derived SI Units (examples)
Quantity unit Symbol
Volume cubic meter m3
Density kilograms per cubic meter
kg/m3
Speed meter per second m/s
Newton kg m/ s2 N
Energy Joule (kg m2/s2) J
Pressure Pascal (kg/(ms2) Pa
Units for Volume m3
cm3
L
mL
When do you use m3 ? irregular objects?
1cm3= 1mL
Tools for measuring:
1. Using a RulerCentimeters and Millimeters
1. Begin on the 1cm mark and make your recording.2. Subtract 1 from the number your recorded to get your answer. For example: 1.5cm - 1.0 cm = 0.5 cm Make sure you include 1 digit after the
decimal. This is usually an estimate.
How to use a metric ruler
3.85 cm - 1.0 cm = 2.85 cm
Let’s Practice
◦ Centimeters are 10 times larger than millimeters so it takes more millimeters for the same length
1 centimeter = 10 millimeter
1 mm
1 mm
1 mm
1 mm
1 mm
1 mm
1 mm
1 mm
1 mm
1 mm
1 cm
4 00
41
411
40
1. Place the graduated cylinder on a flat surface.2. Read from the bottom of the meniscus (bubble) at EYE LEVEL.3. Again you want to estimate.
2. Graduated cylinder
How to read a graduated cylinder
Graduated Cylinder - Meniscus
1. Move all sliders/masses to the left.
2. Check to see if the mark on the moving arm
lines up with the 0 on the balance.
3. Place specimen on pan then move the sliders
until the marks line up at 0.
3. Triple – beam balance
How to use a triple-beam balance
Let’s Practice
1. Place the electronic balance on a flat, stable surface indoors. 2. Press the "ON" button and wait for the balance to show zeroes on the digital
screen.3. Use a container for your object to be massed (never place directly on the
balance).4. Press the "Tare" or "Zero" button to automatically deduct the weight of the
container from future calculations. The digital display will show zero again, indicating that the container's mass is stored in the balance's memory.
5. Carefully add the substance to the container. Ideally this is done with the container still on the platform, but it may be removed if necessary. Avoid placing the container on surfaces that may have substances which will add mass to the container such as powders or grease.
6. Place the container with the substance back on the balance platform if necessary and record the mass as indicated by the digital display
4. Digital BalanceHow to use a digital balance
Picture here,..
Why do we use the SI/Metric System?
To making accurate and precise measurements.
Percent Error
% Error= |experimental –accepted| x100
accepted value