Chemistry I Honors

“Unit I: Matter and Scientific Calculations”

*The material in Objectives # 1-3 should have been mastered in previous coursework. Laboratory exercises will be performed to review the material.

*You should be able to answer the questions listed in your homework packet; Ask for additional assistance if needed; these types of questions will appear on the unit test.

*Worksheets #1, p.11, Activity 1-3

Objectives #1-6: Matter – Properties and Changes

*Review the list of elements/symbols and polyatomic ion names/formulas

*You should be familiar with your list of symbols and names for the Unit 1 Test.

*The list of polyatomic ions should be memorized before we begin Unit 5.

Objectives #1-6: Matter – Properties and Changes

Please don’t forget to record any notes from

the Water Filtration Lab that you may wish to review as you prep for

this unit test.

Notes from Lab:

Classification of Matter

Matter

Pure Substances

Elements Compounds

Mixtures

Homogenous Heterogeneous

Matter - has mass and volumePure Substances - one type of matter,

definite compositionMixtures - more than one type of matter, no

definite compositionElements - can’t be broken down chemicallyCompounds - can be chemically broken downHomogeneous Mixtures (solutions) - can

be physically separated, uniformHeterogeneous Mixtures - can be

physically separated and not uniform

Classification of Matter

Sections of the Periodic Table

The Periodic Table…

Groups: 1-18; Run vertically; similar chemical properties due to electron configurationsPeriods: 1-7; Run horizontally; same number of energy levels to hold electrons of elements

Metals: Groups 1-16 (under the stairstep line)Luster

Conducts electricity Malleable Ductile High melting point Generally solids at room temperature

Types & Basic Characteristics of Elements

Nonmetals: Groups 13-18 (above the stairstep line)

Dull Insulator Brittle Low melting point Exist as solids, liquids & gases at room temperature

Types & Basic Characteristics of Elements

Metalloids: Along the stairstep line, except

Aluminum (#13) & Polonium (#84)Have a somewhat metallic luster

Semi-conductorLess malleable than metals, but not brittleIntermediate melting pointsSolids at room temp

Types & Basic Characteristics of Elements

*You should be able to solve the text problems listed below; please come in for help immediately if you need assistance; these types of problems will appear on quizzes and the unit test

P.40 # 1-3 P. 59 # 7, 16, 19

P.42 # 1,2,3,5 P. 60 # 43, 44P. 57 # 7, 8

Objectives #7-13:Basic Math Skills

*All measurements contain some error; the quality of measurements can be determined by determining their: Accuracy-closeness of a measurement to the true value Precision- consistency of repeated measurements

*Accuracy can be measured by calculating the percent error

Observed Value – Actual Value x 100 Actual Value

Objectives #14-16Using Scientific Measurements

*example:500 grams vs. 499 grams499 grams – 500 grams / 500 grams X 100 =-.2%

2 grams vs 1 gram1 gram – 2 grams / 2 grams X 100 =-50%

*Precision can be determined by significant figures

*Significant figures are all digits in a measurement known with certainty, plus the last digit that is estimated

Using Scientific Measurements

*Determining significant figures involves a set of rules summarized on p.47 of text

*Examples: 100, 100.01, .800, .00180, 1002

*Practice Problems: 3.0 ____ .10004 ____ .0020 ____ 3000 ____ 2.4421 ____

Determining Significant Figures

42.0040 ____ 53.00 ____ 200. ____ 6.300 X 104 ____ 5.00700 X 10-6 ____

Try these yourself!

*When adding and subtracting, the number of digits after the decimal in the final answer can’t be more than the least number of digits after the decimal in any of the individual measurements

*Examples:

Using Significant Figures

22.11 + 45.6 = 67.71 =67.7

3000. – 272 = 2728 =2728

190. + 9.2 = 199.2 =199

18.111 – 9.44 = 8.671 =8.67

*When multiplying and dividing, the number of significant figures in the final answer can’t be more than the least number of significant figures in any of the individual measurements

*Examples:

Using Significant Figures

27.926 X 13.0 = 363.038 =363

3.2 X 105 X 9.86 X 10-3 = 3.1552 X 103 =3.2 X

103

1.764 X 104 / 4.41 X 102 = 40 =4.00 X 101

.365 / .200 = 18.25 =18.3

*Key Steps: Analyze (identify known and unknown) Plan Compute Evaluate (units, reasonable, sig. figs.)

*See examples in lecture guide

Problem Solving in Chemistry

1. Convert 14 cm to meters.14 cm X 1 meter / 100 cm = .14 m

2. Convert 1.47 X 105 mm to kilometers.1.47 X 105 mm X 1 meter / 1000 mm X 1 km /

1000 m = .147 km

3. A buret delivers .15 cm3 of water per second. How much time is required to transfer 18 grams of water? Assume 1 cm3 = 1 gram for water.

18 grams X 1 cm3 / 1 gram X 1 second / .15

cm3 = 120 seconds4.The density of an object is 7.5 g/ml.

Calculate the mass in grams of a 1.2 L sample.

1.2 L X 1000 ml/1 L X 7.5 g / 1 ml = 9.0 X 103 g

5. A ant travels at a speed of .005 km/day. Convert to cm / ms.

.005 km / day X 1000 m / 1 km X 100 cm / 1m X 1 day / 24 hours X 1 hour / 60 min X 1 min / 60 s

X 1 s / 1000 ms = 6 X 10-6

6. A 3% by mass solution of hydrogen peroxide contains 3 grams of hydrogen peroxide per 100 grams of hydrogen peroxide solution. Calculate how many grams of hydrogen peroxide are contained in 56.5 g of a 3% hydrogen peroxide solution.

56.5 g solution X 3 grams of hydrogen peroxide / 100 grams solution = 1.70 g hydrogen peroxide