Making Measurements & Using the METRIC SYSTEM

1. Making Measurements & Using the METRIC SYSTEM Adv. Honors Chemistry Braintree High School

2. Types of OBSERVATIONS • Quantitative: • Tells us how many. • Describes “Quantity” • Describes observations with numbers. • Qualitative: • Tells us about it. • Describes “Quality” • Describes observations with words.

3. Qualitative Vs. Quantitative • His shirt is red. • There are 2 apples left. • The table is 5 meters long. • A blue crystal formed on the bottom of our 100mL beaker. • Her shirt is 100% cotton.

4. What are units? • Steve has 10. • There are 43.6 of salt. • Numbers do not make sense if there is no unit. • A unit tells us what the number measures. • In science class there are NO NAKED NUMBERS- make them appropriate with a unit!

5. The International System of Units • ALL SCIENTISTS us the International System of Units. • We abbreviate it as SI. • Some good things about measuring in SI: • It is based on multiples of 10. • There are no fractions- we use decimals in the metric system. • Allows results to be easily shared between countries.

6. Who uses the SI system? • In everyday life, just about everyone except for US! • These countries do not use the metric system: • The United States of America • Liberia • Myanmar • ALL SCIENTISTS IN THE WORLD USE THE SI SYSTEM OF MEASUREMENT!

7. What are prefixes? • Pre means “before” • A prefix is a small part of a word that comes before the word. • Metric prefixes equal a number.

8. Common Metric Prefixes

9. Adding prefixes • When we measure, we can add a prefix to change the value. • 1 nanosecond = how many seconds? • Find nano- on your chart. • What does it mean? • 1 nanosecond = 10-9 seconds • 1 kilometer = 1000 meters • 1 milligram = 0.001 grams

10. Rules for writing metric symbols • Do not use a period. • 7 s [not 7sec.] • Leave a space. • 6 kg [not 6kg] • Do not add an s to the symbol. • 10 Kilometers = 10 km [not 10 kms] • Do not capitalize, unless it is supposed to be capital. • Milliliter = mL [not Ml] • Do not use p for per. • miles per hour = mi/hr [not mph]

11. Write the correct units mm = millimeter mg = milligrams L = liter Mg = Megagram m = meter dam = decameter g = gram cm = centimeters ns = nanosecond

12. Which number is bigger? • 4 cm or 4 hm • 10 km or 10 mm • 12g or 12 kg

13. What will we measure? • Length • Distance between two points. • Mass • Amount of material in an object. • Temperature • Amount of heat a material has. • Volume • Amount of space an object takes up.

14. What are BASE UNITS? • A base unit is the standard unit of measurement that we will use to measure. • We will add prefixes to the base units.

15. Measuring LENGTH • The SI base unit of measurement for length is the METER. • 1 meter = 1m • Your desk is about one meter tall. • You can use a METRIC RULER or a METERSTICK to measure length. Ribisi/Diozzi

16. Other units of length • If you wanted to measure between cities, you would use KILOMETERS. • A kilometer is equal to 1,000 meters. • If you wanted to measure small lengths, you would use a centimeter or a millimeter. • There are 100 centimeters in a meter. • Just like there are 100 cents in a dollar. • There are 1000 millimeters in a meter.

17. Practice! • How much carpet do you need to cover the floor in a room that measures 7 meters long and 5 meters wide? • L = 7 m • W = 5 m • A = L X W A = 7 m X 5 m A = 35m2

18. Measuring VOLUME of a liquid • The SI base unit of measurement for volume is the LITER. • 1 Liter = 1L • You will use different units and tools to measure volume of a liquid or a solid. • You can use a GRADUATED CYLINDER to measure the volume of a liquid.

19. Graduated cylinders measure in mL or milliliters. • The plastic ring around a graduated cylinder prevents breaking. • To read a graduated cylinder: • Move to eye level. • Read the bottom of the meniscus.

20. VOLUME of a solid • If you are trying to find the volume of a solid, you cannot pour it into a graduated cylinder. • Methods: • Water displacement • Calculating volume

21. Water Displacement

22. What steps will you take to measure with water displacement? • Put water in the graduated cylinder. • Record the measurement. • Tilt the graduated cylinder to the side. • Gently lower the object into the graduated cylinder. (Make sure that the whole object is under water.) • Record the measurement. • Water & Object – Water = Object’s volume • REMEMBER 1 ml = 1 cm3 = 1 cc

23. Calculating Volume of a Block • To find the volume of a regular (block or box shaped) solid, you need to measure the length, width and height IN THE SAME UNIT and multiply these three numbers together. V= L X W X H • What is the volume of the black cube? • What is the volume of the bigger cube? • Volume = length X width X height • V = 3 cm X 2 cm X 2 cm • V = 12 cm3

24. Measuring MASS • The SI base unit of measurement for mass is the GRAM. • 1 gram = 1g • A paperclip is about 1 gram. • You can use a TRIPLE BEAM BALANCE or an ELECTRONIC SCALE to measure mass.

25. Other units of mass • If you wanted to measure large masses you would use KILOGRAMS. • 1 Liter of pop has a mass of about 1 kilogram. • If you wanted to measure the mass of smaller objects, you would use milligrams or centigrams. • When have you heard someone say milligrams?

26. Ribisi/Diozzi

27. Measuring TEMPERATURE • The SI base unit of measurement for temperature is Kelvin (K). • A more common unit is DEGREES CELSIUS. • 1 degrees Celsius = 1ºC • You can use a THERMOMETER to measure temperature.

28. Measuring TIME • The SI base unit of measurement for time is the SECOND. • 1 second = 1s • We will use a STOPWATCH to measure time in science class.

29. Write this chart: • Find the unit you are starting with. • Find the unit you want to change to. • Count the number of spaces you have to move. • Which way did you move? • Move the decimal in that direction that number of spaces.

30. How can we remember the order of the chart? • Kids Have Dropped OVER Dead Converting Metrics • Kilo HectoDecaOVER DeciCentiMilli meter liter gram • What is your mnemonic device?