SI – International System of Units SI - (AKA International System of Units or S.I.) is a measuring system based on units of 10. Math – the language of science Units 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 (metric) prefixes 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 1/10 1/100 1/1000

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 Units meter gram liter 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 Units meter gram liter 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 centimeters or 1.00 meter = 10.0 decimeters = 100. centimeters kilo hecto deca meter liter gram deci 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 deca meter liter gram deci 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 UNITS meter liter gram deci centi milli

Practice problems:

Base SI Units Quantity Unit Symbol Length meter m Mass kilogram kg Temperature kelvin K Time second s Amount of Substance mole mol Luminous Intensity candela cd Electric Current ampere a

Other - SI Unit Prefixes Name Symbol giga- 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 1cm3= 1mL m3 cm3 L mL When do you use m3 ? irregular objects? 1cm3= 1mL

Tools for measuring:

1. Using a Ruler Centimeters and Millimeters

How to use a metric ruler 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.

Let’s Practice 3.85 cm - 1.0 cm = 2.85 cm

Centimeters are 10 times larger than millimeters so it takes more millimeters for the same length 1 centimeter = 10 millimeter 4 00 411 1 mm 40 41 1 cm

2. Graduated cylinder How to read a graduated cylinder 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.

Graduated Cylinder - Meniscus

3. Triple – beam balance How to use a triple-beam balance 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.

Let’s Practice

4. Digital Balance How to use a digital balance 1. Place the electronic balance on a flat, stable surface indoors. Press the "ON" button and wait for the balance to show zeroes on the digital screen. Use a container for your object to be massed (never place directly on the balance). 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. 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. Place the container with the substance back on the balance platform if necessary and record the mass as indicated by the digital display

Picture here,..

Why do we use the SI/Metric System? To making accurate and precise measurements.

Percent Error % Error= |experimental –accepted| x100 accepted value