Intro to chem unit 1

 Is a statement NOT a question that expresses the expected answer to the problem statement what you think the results of the experiment will show  If you increase the amount of salt ad

Introduction to Chemistry

The study of:

 the composition

(make-up) of matter

 the changes that

matter undergoes

The 5 Traditional Branches of Chemistry

Inorganic Chemistry

 The study of chemicals that do not

contain carbon.

 Study of properties and changes of

matter and energy

 Study of processes that take place

in organisms.

 Understand the structure of matter

found in the human body and the

chemical changes that occur in cells

Science and Technology

 Theoretical Chemistry-Design of new compound

and new ideas; 2 categories: pure and applied

 Has practical applications in society

 Directed toward a practical

goal/application Engineering

Al chem ists (~300BC-1650 AD)

China, India, Arabia, Europe, Egypt

•Mystical.

The Scientific Method

scientific investigations

technique

method is Galileo Galilei and Francis Bacon

Scientific Method

 Observation- recognition of a problem

 Visible or provable fact

 From that a question arises (problem

 Is a statement NOT a question that expresses the

expected answer to the problem statement (what you think the results of the experiment will show)

 If you increase the amount of salt added to the water, the boiling temperature will also increase because

Scientific Method

 Experiment- an organized procedure used to

test a hypothesis (measurement, data

collection, manipulated and responding

variables)

 Planned way to test the hypothesis and find out the

answer to the problem posed

 Way to collect data and determine the value of the

 Constants-parts of your experiment

that do not change

Scientific Method

 Independent Variable

 A variable that changes unrelated to other factors

 A variable we manipulate, change, on purpose

 A variable whose value we know before we start an

experiment

 Example: Does the amount of salt in water affect

the boiling temperature of water? We know how much salt we add to each amount of water before boiling so amount of salt is the independent variable

Scientific Method

 Dependent Variable

 A variable that changes depending on some other

factors

 The variable we are trying to find out

 Variable whose value we do not know before we start

the experiment

 Example: Does the amount of salt in water affect

the boiling temperature of water? We do not know the boiling temperature to water once salt is added; must test to find this out

Scientific Method

 Constants

 Does not change for the duration of the experiment

 Remains the same

 Example: Does the amount of salt in

water affect the boiling temperature of water? We would not change the brand

of salt or the amount of water (or type

of water)

 Data presented via tables or graphs

 3 types of graphs: circle (pie), bar, line

Scientific Method

The cafeteria wanted

to collect data on

how much milk was

sold in 1 week The

table shows the

results We are

going to take this

data and display it in

Scientific Method

 A bar graph is used to

show relationships between groups.

 The two items being

compared do not need

to affect each other.

 It's a fast way to show

big differences Notice how easy it is to read a bar graph.

 Often used for

Monday Tuesday Wednesday Thursday Friday

 This kind of graph is

needed to show percentages effectively

 Sum of parts is 1 or

100%

Chocolate Milk Sold

Monday Tuesday Wednesday Thursday Friday

Scientific Method

 Line Graph

 A line graph is used

to show continuing data; how one thing is affected by another

 It's clear to see how

things are going by the rises and falls a line graph shows

 Equation of line

represents the data

Chocolate MIlk Sold

0 20 40 60 80 100 120

Monday Tuesday Wednesday Thursday Friday

Scientific Method

 Choosing the right graph for your data

 Use a bar graph if you are not looking for trends (or

patterns) over time; and the items (or categories) are not parts of a whole

 Use a pie chart if you need to compare different

parts of a whole, there is no time involved and there are not too many items (or categories)

 Use a line graph if you need to see how a quantity

has changed over time.  Line graphs enable us to find trends (or patterns) over time

Scientific Method

 Conclusion

 Presents the findings of the

experiment, what the data shows, the hypothesis and whether or not it was correct (supported) or incorrect

(negated)

 Theorizes why the observed pattern

is so

Scientific Method

 Communicate

 When scientists collaborate (work

together) and communicated, they increase the likelihood of a successful outcome

 Journals

 Internet

 Presentations/Speeches

 A well tested explanation for a broad set of

observations

 May use models

 May allow predictions

 Theories may change to explain new

observations or experimental data.

Law

 A statement that summarizes results of

observations, but does not explain them.

 Concise statement that summarizes the results

of many observations and experiments

 Changes or is abandoned when contradicted by

new experiments.

 The order of the steps can vary and additional

steps may be added.

Math and Chemistry

 Math- the language of Science

 SI System (Metric System)

 Factor Label Method (Dimensional

Analysis)

 Significant Figures

 Scientific Notation

 Manipulating Formulas

 SI Units – International System

 Basic Units abbreviation

Length (meter) m Mass (kilogram) kg

Solving Word Problems

 If needed, rearrange the equation to solve

for the unknown

 Substitute the knowns with units in the

equation and express the answer with units

 Evaluate