Introduction to Chemistry

What is Chemistry? The study of the composition of matter and the changes that matter undergoes The study of the composition of matter and the changes that matter undergoes

Five major branches of chemistry Organic Organic

Inorganic Inorganic

Analytical Analytical Physical Physical Biochemistry Biochemistry

Why study Chemistry??? Pure Chemistry Pure Chemistry Applied Chemistry (Technology) Applied Chemistry (Technology)

Chemistry plays a big part in our lives We are in the “Age of Plastics” We are in the “Age of Plastics” High “strength to weight” ratio High “strength to weight” ratio

Energy New fuels New fuels New insulation material New insulation material

Energy from the sun Energy from the sun Hydrogen cells Hydrogen cells Storage batteries Storage batteries

Medicine and Biotechnology Medicines Medicines Surgical breakthroughs Surgical breakthroughs Genetic research Genetic research

Agriculture Protect crops Protect crops Increase food supply Increase food supply Increase strength and vitality of plants Increase strength and vitality of plants

Environment Pollution Pollution Catalytic converters Catalytic converters Acid rain Acid rain Ozone layer Ozone layer

SCIENTIFIC METHOD

1. Observation Gather data: qualitative or quantitative

2. Hypothesis t tentative explanation for what is observed (educated guess)

3. Experiments – set of controlled observations that test a hypothesis

–Independent variable – one you are going to change

–Dependent – changes depending on the independent variable

–control – standard for comparison –Model – visual, verbal and/or mathematical explanation of experimental data

Conclusion – judgment based on the information obtained – judgment based on the information obtained

Theory – explanation that has been supported by MANY experiments – explanation that has been supported by MANY experiments

Scientific Law – describes a relationship in nature that is supported by many experiments. – describes a relationship in nature that is supported by many experiments.

Types of observations Qualitative observations – describe a substance without using numbers “It is heavy” “ It is blue” “It smells”

Quantitative observations – use numbers 87 millimeters 10 liters 4.0 g/ml

Scientific Notation 765,000,000, X Move decimal to the left – is positive X Move decimal to the right – is negative Samples on handout

Write in standard notation 4.5 x x

 Is how close a measurement is to the correct or accepted value

 How close a series of measurements are to each other  (how close a measurement is to other measurements of the same thing)  Dartboard example

 Assures the certainty of measurements  For any measurement, scientists only record all the digits they are certain of, plus one estimated figure  Together, they are called “significant figures”

 meters  All the digits are significant. Which one is the estimated and which are certain?  6,2,3,4 are certain  5 is estimated

 A scientist measures 89 seconds  All are significant  Which are certain and which are estimated?  8 is certain  9 is estimated

 Rule 1 – all nonzero digits are significant – 1,2,3,4,5,6,7,8,9 – are significant  Rule 2 – Final zeroes to the right of the decimal point are significant  sig figs

 Rule 3 – zeroes between two significant digits are significant  sig figs  sig figs

 Rule 4 – zeroes used for spacing the decimal point are not significant  sig figs  sig figs

 Rule 5 – for numbers in scientific notation, all of the digits before “x 10 x ” are significant  x sig figs

 sig fig  sig figs

Let’s practice!! sig figs sig figs 200,035 6 sig figs sig figs

sig figs sig fig 4.44 x sig figs 2.0 x sig figs

sig figs 10 1 sig fig sig figs 102,000 3 sig figs