WARM UP Agenda Notes Unit 1-5 Lab Density Homework Aug 26 - Notebook check Unit 1 Aug 29 - Online HW Unit 1 Aug 30 - Test Unit 1 1. Provide 2 examples Compound Matter Homogeneous Heterogeneous

Unit 1-5 Density and Rounding Measurements

Properties of Matter Chemical Properties: A property of matter that let it react with another chemical Chemical properties can only be identified by trying to cause a chemical change

Properties of Matter Physical Property: A property that can be determined without changing the nature of the substance Example: sugar’s physical properties would include that it is solid, white More examples: State of matter Melting points Boiling point Mass and volume Density

Properties of Matter Density = mass ÷ volume Unit is g/cm 3 The density of an object is the same no matter its volume

Density Example Problems 1. What is the density of an object that weights 2200g and has a volume of 100cm 3 ? 2. Gold’s density is 19.3g/cm 3 If a gold bar has mass of 150g what is its volume? 3. Find the density of this cube. Mass = 30g

Rounding Measurements Accuracy- how close a measurement is to the actual value

Rounding Measurements Precision- how frequently you get the same measurement when measuring in the same way

Rounding Measurements Round the following numbers: 5.76 to the nearest tenths 453 to the nearest tens to the nearest hundredths

Scientific Notation Used to make numbers easier to deal with and to keep track of zeros Only one number before decimal! Using calculators with scientific notation: Number * 10 ^ (exponent) Number EE (exponent)

Scientific Notation Examples

Density Lab Follow the lab procedure to find the volume of pennies and metal cylinders Find the unknown materials used to make the cylinder objects and the cubes by finding its density

Assignments Summary - Describe a way to measure the volume of a gold necklace.

EXTRA NOTES NOT APPLICABLE

Significant Figures Significant figures are used to indicate the preciseness of measurements - Significant figures consist of all the digits known with certainty as well as one estimated, or uncertain digit - Use for rounding answers

Rules for Determining Significant Figures 1. Nonzero digits are always significant e.g has 4 sig figs 2. Zeros between nonzero digits are significant e.g. 909 has 3 sig figs 3. Zeros in front of non zero digits are not significant e.g has 2 sig figs e.g

Rules for Determining Significant Figures 4. Zeros both at the end of a number and to the right of a decimal point are significant e.g has 3 sig figs 5. Assume zero to the right of a number but to the left of the decimal point is not significant e.g has 1 sig fig, but 30.0 has 3 sig figs

Sig Fig Practice Determine the number of sig figs in each value a) b) 4006 c) d) 0065 e) f) 3.0 g) 700

Sig Figs in Calculations When multiplying and dividing, round your answer to the least number of sig figs in the equation Multiplying and Dividing a) 12 x 4 = ? b) 1.0 x 623 = ?

When adding and subtracting, round your answer to the least number of decimal places in any of the data you are given. Adding and Subtracting a) = ? b) – 2.23 = ? Sig Figs in Calculations