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Introduction to

Chemistry

Lorena Ma. Wheelock Gtz.

1.1 The Stories of Two Chemicals.

1.2 Chemistry and Matter.1.3 Scientific Methods.

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1.1 The Stories of Two ChemicalsThe Ozone Layer

Ozone (O): is a chemical that absorbs radiation

before ot reaches Earth.Is located in the stratosphere, this

layer is above the troposphere. It

extends from 15-50 km. above the

Earths surface.

Stratosphere

Living things can e

xist onEarth because of

OZONE

Where does the ozonelayer is located?

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The Ozone Layer

Radiation from

sun causes

oxygen to break

into two identicalparticles of

oxygen. These

individual oxygen

particlescombine with

oxygen gas to

form ozone,

How ozone forms?

which consists of three oxygen particles.

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The Ozone Layer

InformationIt was 1st. Identified and

measured in the late 1800s

Ozone forms over theEquator where the rays

of sunlight are

strongest and the flow

toward the poles.

G. M. B. Dobson

began to measure

the amount of

ozone in the

atmosphere, more

than 300 D.U.

(Dobsons Units)

1800

1900

1920

1981-1983

1985

A research group from

British Antarctic

Survey was

monitoring the

atmosphere above the

Antarctica. They werelow levels of ozone

less than 160 D.U.

In Octoberwas confirmed

the decrease

of the amount

of ozone, and

that the ozonelayer was

thinning.

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1.1 The Stories of Two ChemicalsChlorofluorocarbons (CFCs)

Is a chemical that contains:chlorine, fluorine and

carbon. At 1935 refrigerators and ser air-conditionersused CFCs as coolants.

Scientists 1st. began to notice the presence

of CFCs on the atmosphere in the 1970s.

Two separate occurrences had been

noticed and measured: the protective ozone layer

was thinning and increasing large quantities of

CFCs were drifting into the atmosphere.

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1.2 Chemistry and MatterChemistry: The Central of Science.

Chemistry: is the study of matter and the change

that undergoes. Is the central of our everyday lives.

Is important because some food and clothes had

pass through a chemical process.

Why do

es the chemistry

is so important?

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Matter: is anything that has mass and takes up

space.

1.2 Chemistry and MatterMatter and its Characteristics:

Mass: is a measurement that

reflect the amount of matter.

Thoughts and ideas are not matter.

Is everything made up ofmatter?

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Matter and its Characteristics:

Mass andWeightWeight: is a measure for the amount on matter

but also of the Earths gravitational energy effect.

Scientist could identify the gravitational force

every time they weigh something, but that wasnt

practical. This is why they use mass as a way to measure

matter independently of the gravitational force.

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1.2 Chemistry and MatterChemistry Branches

Chemistry

Analytical

ChemistryPhysical

Chemistry

Inorganic

Chemistry

Organic

Chemistry

Biochemistry

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1.3 Scientific MethodsA Systematic Approach:

Scientific Method: is a systematic approach used

in scientific study. It is an organized process used by

scientists to do research, an it provides a method forscientists to verify the work of others.

Steps:

*Observation

*Hypothesis*Experiments

*Conclusion

*Theory

*Scientific Law

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A Systematic Approach:Steps

*Observation: is the act of gathering information,types of observation that scientists first make are

qualitative data (color, odor, shape, etc.) in chemistry it

is: temperature, pressure, volume, etc.

*Hypothesis: is a tentative explanation for whathas been observed. Is stated what they believe to be

happening, a data to support.*Experiments: is a set of controlled observations

that test the hypothesis, the results can be:independentvariable: temperature,dependent variable:value

change in response to change the independent

variable. And experiment have a valuable control, a

standard comparison.

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A Systematic Approach:Steps

*Conclusion: is a judgment based on theinformation obtained. The hypothesis can never be

true you just gave the affirmation that maybe it can be

true.*Theory: is an explanation that has been

supported by many, many experiments. States a broad

principle of nature that has been supported over time.

It lead to new conclusions.

*Scientific Law: is a relationship in nature thatsupported by many experiments, it is up to scientists

to develop further hypotheses and experiments to

explain why this relationship exist.