Introduction to Chemistry

Matter

A mixture that has visibly different parts(Ex: Granite, chocolate chip cookie, can

be separated by physical properties.)

Heterogeneous Mixtures

Also known as solutions.Does not have visibly different parts, but

can be separated by physical props.(Ex: salt water, air)

Homogenous Mixtures

Mixtures

Composed of two or more elementsEx: Water, rust, carbon dioxide.

Can be broken down into elementsby their chemical properties.

Compounds

Composed of Protons,Neutrons and Electrons

Atoms

A substance that cannot be brokeninto smaller pieces and

maintain the properties of thatelement. (ex: Oxygen, iron)

Elements

Pure SubstancesHas its own uniques set of chemical

and physical properties

MatterAnything that has mass and volume

Measurements in science are handled using the metric system:

length - meters volume - liters

mass - grams

You can use very large or very small numbers like

5 000 000 g or 0.000 000 005 g5 000 000 g or 0.000 000 005 g

You can rewrite them in scientific notation

5 x 10 6 g or 5 x 10 -9 g5 x 10 6 g or 5 x 10 -9 g

Or you can use metric prefixes that represent exponential values of 10

5 Mg (M=106) or 5 ng (n = 10 -9)5 Mg (M=106) or 5 ng (n = 10 -9)

Prefix Symbol Meaning Exponential Notation

Exa E 1,000,000,000,000,000,000 1018

Peta P 1,000,000,000,000,000 1015

Tera T 1,000,000,000,000 1012

Giga G 1,000,000,000 109

Mega M 1,000,000 106

Kilo k 1,000 103

Hecto h 100 102

Deka da 10 101

----- ---- 1 100

Deci d 0.1 10-1

Centi c 0.01 10-2

Milli m 0.001 10-3

Micro 0.000001 10-6

Nano n 0.000000001 10-9

Pico p 0.000000000001 10-12

Femto f 0.000000000000001 10-15

Atto a 0.000000000000000001 10-18

Try on your own:

140 000 000 000

34 000

564 878 000

0.000 000 000 000 26

0.000 000 511

1.4 x 10 11

3.4 x 10 4

5.64878 x 10 8

2.6 x 10 -13

5.11 x 10 -7

Scientific Notation

Scientific Notation

A way to simplify very large or very small numbers

9 000 000 000 = 9.0 x 10 9

0.000 000 34 = 3.4 x 10 -7

Rules

1. You may only have one digit to the left of the decimal

2. That digit must be > 1 but < 9

3. Count the number of places you have moved the decimal from its original location and make it the exponent in

x 10 ?

If the decimal is moved left the exponent is +

If the decimal is moved right the exponent is -

: a.) 0.0023 g b.) 2.40 L c.) 2 centuries

d.) 250 inches e.) 432 ft f.) $28.04

Answers: a)2, b.) 3, c) infinite, d) 2, e)3, f) 4

How much do you remember about

significant digits??

Identify the number of sig figs in each of the following numbers.

Significant figures are a way to deal with uncertainty in Measurement.

Rules for significant figures:1. All nonzero digits are significant2. All zeros between non zero digits are significant3. Leading zeroes are NOT significant4. Trailing zeroes are NOT significant if there is no decimal point in the

number.5. Exact numbers such as counted numbers or numbers in a

Definition like 1 dozen =12 pieces do not have an affect on aCalculation, they are considered to have an infinite number ofSignificant figures.

Try again:

a) 347 mL

b) 0.0045 g

c) 100 oz

d) 85.0 mL

e) 4075 kg

f) 0.0560 m

g) 520. g

h) 8.000 g

i) 0.302 lb

j) 1006 m

Significant Figures in calculations

Muliplication and DivisionFind out how many sig figs are in each number in the problem.

2.36 x 1.631

3 4

Do the math 2.36 x 1.631 = 3.84916

Your answer must now be rounded off to the lowest

number of sig figs present in the problem, in this case, 3

Answer 3.85

You can only be as certain as your least certain instrument.

Practice (Rules for multiplication and Division are the same.)

1.) 12.3 x 3.6 x 0.4356 =

2.) 15 ÷ 4.21 =

3.) 3.145 x 103 x 6.1 x 1012 =

4.) 3.18 x 103 x 6.4 x 10-4 =

19.288368 =

3.56294537 =

1.91845 x 1016 =

2.0352 =

19

3.6

1.9 x 10 16

2.0

Addition and Subtraction

1. Line up numbers at decimal point, complete addition of subtraction

2. Where number is rounded depends on the least certain value, meaning the place value closest to the decimal.

12.364 + 121.1 = ?

12.364

121.1

133.464

Tenths place value is least certain so round at that place value

= 133.5

This buret is graduated by 0.1 mL increments. Your measurement can be certain to the tenths place value. Even though you can predict a number in the hundredths place value, it may be different depending on who you are. Therefore, it is an uncertain number.

Person Reading

1 20.15 mL

2 20.14 mL

3 20.16 mLSince each person has a variance of 0.01 mL, we say the measurement is

20.1X + 0.01 mL

This instrument is called an analytical balance. It reads to 4 places past the decimal point.

With uncertainty factored in, we would read this measurement as

89.2863 + 0.0001 g

On an instrument this sensitive the last number fluctuates constantly so even though it has a digital readout you may have it reading 2 numbers without settling on either one.

Completely random data.

Somewhat organized. All information collected in one location

Very organized. All information collected in expected location

Precision - Reproducibility for each trial of an experiment

Accuracy - Agreement with a known value

Precision and Accuracy

Temperature scales in science

Metric System - Celsius after the Swede Andres Celsius. He set freezing of H2O as 0°C and boiling at 100 °C then broke up the scale into 100 pieces.

Kelvin - Based on research in gas laws done by Lord Kelvin. He found that all gases eventually reach the same temperature if cooled, -273 °C . He set this as O K or Absolute Zero.

To convert between Celsius and Kelvin:

K = C + 273

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Some important people to know! (Because they discovered the particles in

an atom or something about them.)

Democritus

First credited with the “idea’ of the atom. Theorized that there were indivisible particles that

made up all matter. Idea was negated by Socrates/Aristotle (who was more popular) and was not accepted again until late 1700’s when John Dalton determined that matter is made up of smaller particles.

Dalton

Law of Conservation of Mass

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Thomson

J.J. Thomson - Credited with the discovery of electrons. Thompson wanted to discover the makeup of the atom and so did experiments that led him to the discovery that there were negatively charged particles in the atom.

Since atom are neutral particles he also guessed that there was some positively charged component to the atom.

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Robert Millikan - Determined the charge of an electron.

Rutherford

Ernest Rutherford - Discovered a large mass that was reflecting back electrons in an atom. Named it “nucleus”. Determined that the positive portion of an atom was located in the center.

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The pieces of an atom

Charge Location Size in relation to Each other

Protons

Neutrons

Electrons

Positive

Neutral

Negative

Nucleus

Nucleus

Electron Cloud

1 amu

1 amu

1/1879 amu

Reading the periodic table

Carbon

C6

12.011

Name

Symbol

Atomic Number

Atomic Mass

Atomic Symbol - An abbreviation of an element’s name. May or may not match the beginning of our language.

Carbon - C

Sodium- Na from latin Natrium

Lead- Pb from latin Plumbum

Atomic Number - Tells number of protons and electrons in an atom.

Atomic Mass - Sum of protons and neutrons in atom

A shortcut way of writing out this information is

12C6

This gives isotopic mass

atomic number

Chemical Symbol

Symbol Name Atomic #

Atomic Mass

Protons Neutrons Electrons

Selenium

25183.85

CaSodium

39

Symbol Element Atomic #

Isotope Mass

Protons Neutrons

Electrons

SO3 -2

CrO4 -2

Na+1

NH4+1

Fe +2

O2-2

Hg2+2

ClO-1

dichromate

aluminum

lead (IV)

potassium

bromide

selenide

cyanide

Density D = m/V

Know your volume formulas for 3D shapes

V=bh V=lwh V=4/3r3 V=1/3r2h

The density of osmium is 22.57 g/cm3. If a 1.00 kg rectangular block of osmium has two

dimensions of 4.00 cm x 4.00 cm, calculate the third dimension of the block.

An iron cylinder has a density of 7.874 g/cm3. If the cylinder weighs 53.25 g and has a height of 6.0 cm, Find the diameter of

the cylinder.

Elements were thought to be limited in number

Early version of the periodic table.