Transcript Chapter 1 Science Skills

Chapter 1
Science Skills
Mr. Bruder
What is Science?
• Science is what scientists do
• Science is trying to explain the world
around us
• Science is a way of thinking
• “Science is a system of knowledge based
on facts or principles
• Book talks about “social science”
• We prefer social studies
Branches of Science
Science
Biological
Science
Physical
Science
Earth
Science
Branches of Science
Science
Biological
Science
Physical
Science
Earth
Science
Zoology
Botany
Ecology
Science of living things
Branches of Science
Science
Biological
Science
Physics
Chemistry
Physical
Science
Earth
Science
Science of matter and
energy
Branches of Science
Science
Biological
Science
Physical
Science
Earth
Science
Geology
The systems of the earth
Meteorology
Astronomy
Branches of Science
• There are many more branches to
biological and earth sciences
• The three categories overlap
• Biochemistry
• Astrobiology
• Geophysics
What is Chemistry?
• The study of matter, its composition,
properties, and the changes it undergoes
• Applied Chemistry is the using of
chemistry to attain certain goals, in fields
like medicine, agriculture, and
manufacturing
• Pure Chemistry gathers knowledge for
knowledge sake
Which Comes First?
•usually
Pure Chemistry
comes first,
applied later
Called technology
Or engineering
Can’t be good or
bad
Applied
Chemistry
Pure chemistry can
explain behavior that
has been used
without knowing why
Steel swords
Can be good or bad
depending on use
Chemistry is
• A natural science
• A language with its own vocabulary
• A way of thinking
Branches of Chemistry
• Analytical Chemistry -studies composition of
•
•
•
•
substances.
Organic Chemistry -compounds containing
carbon
Inorganic Chemistry -substances without
carbon
Biochemistry- Chemistry of living things
Physical Chemistry studies behavior of
substances
– rates and mechanisms of reactions
– energy transfers
Science From Curiosity
• Science begins with curiosity and often
ends with discovery.
• How or Why is this possible?
• Curiosity provides questions but is seldom
enough to achieve scientific results.
• Then how do we achieve these results?
Observations
• Qualitative – describe with words
– Hot , red, large
• Quantitative – describe with numbers
– 100° , 10 meters, 3.46 grams
• Scientists prefer quantitative
• Easy to agree upon
• No personal bias
Models
• A representation of some object or event
• Made to better understand it
• Often used if real thing is too big, small or
complex.
• Come in a variety of forms
– Physical models
– Diagrams
– Computer models
The Scientific Method
• A way of thinking about and solving
problems
• It is a logical method
• You do it all the time
Scientific Method
• A way of solving problems or answering
questions
• Starts with observation- noting and
recording facts
• Hypothesis- an educated guess as to the
cause of the problem or answer to the
question
Scientific Method
• Experiment- designed to test the
hypothesis
• Only two possible answers
• 1) hypothesis is right
• 2) hypothesis is wrong
• Generates data observations from
experiments
• Modify hypothesis- repeat the cycle
The Scientific Method
• Does not always work this way, but gives
a way of guiding our thinking
• Hard part is testing only one variable at a
time.
• Changing only one thing at a time
• If you change more than one, you don’t
know which one is the cause
Variables
• Controlled experiment- Only want one
thing to change at a time in a laboratory.
• Manipulated variable- What you change or
control directly
• Also called independent variable
• Responding variable – What changes as a
result. No direct control
• Also called dependent variable
• Cycle repeats many
Observations
Hypothesis
Experiment
•
•
•
times.
The hypothesis gets
more and more
certain.
Becomes a theory
A thoroughly tested
model that explains
why things behave a
certain way.
• Theory can never
Observations
Hypothesis
Experiment
be proven.
• Useful because they
predict behavior
• Help us form mental
pictures of
processes (models)
• Another outcome is
Observations
Hypothesis
Experiment
that certain behavior
is repeated many
times
• Scientific Law is
developed
• Description of how
things behave
• Law - how
• Theory- why
Observations
Hypothesis
Theory
(Model)
Modify
Experiment
Prediction
Law
Experiment
Law vs. Theory
Law
Theory
Describes how
Explains why
Summarizes
observations
Agrees with
observations
Usually an
equation
Predicts new
discoveries
Law vs. Theory
• Theory can’t be proved; always the
possibility that a new experiment will
disprove a theory
• Law described a natural phenomenon, but
does not attempt to explain it
Measurement
• How do we measure in science?
• What do measurements mean?
• How do we tell?
• Let’s start with Accuracy vs. Precision
How good are the measurements?
• Scientists use two words to describe how
good the measurements are• Accuracy- how close the measurement is
to the actual value
• Precision- how well can the measurement
be repeated
Differences
• Accuracy can be true of an individual
measurement or the average of several
• Precision requires several measurements
before anything can be said about it
Let’s use a golf anaolgy
Accurate? No
Precise? Yes
Accurate? Yes
Precise? Yes
Precise?
No
Accurate? Maybe?
Accurate? Yes
Precise? We cant say!
Examples
a. Multiple
b.
c.
d.
e.
f.
Measurements
Correct
Repeatable
Reproducible
Single Measurement
True Value
Scientific Notation
• To write in Scientific Notation you need a
number between 1 & 9 in front of the
decimal.
• When going from right to left you add the
exponent (positive exponent)
• When going from left to right you subtract
the exponent (negative exponent)
Converting Cont.
• Examples
I. 345
II. .000345
III. 56890
IV. .000000000134
The Metric System
Measuring
• The numbers are only half of a
measurement
• It is 10 long
• 10 What?????
• Numbers without units are meaningless
The Metric System
• Easier to use because it is a decimal
system
• Every conversion is by some power of 10
• A metric unit has two parts
• A prefix and a base unit
• Prefix tells you how many times to divide
or multiply by 10
Base Units
• Length - meter more than a yard - m
• Mass - grams - a bout a raisin - g
• Time - second - s
• Temperature - Kelvin or ºCelsius K or C
• Energy - Joules- J
• Volume - Liter - half f a two liter bottle- L
• Amount of substance - mole - mol
Prefixes
• kilo k 1000 times
• deci d 1/10
• centi c 1/100
• milli m 1/1000
• kilometer - about 0.6 miles
• centimeter - less than half an inch
• millimeter - the width of a paper clip wire
Volume
• Calculated by multiplying L x W x H
• A liter volume of a cube 1 dm (10cm) on a
side….
• So 1L = 10cm x 10cm x 10cm
• 1L = 1000cm3
• 1/1000L = 1 cm3
• 1mL = 1cm3
Mass
• Weight is a force. Mass is the amount of
matter.
• 1g is defined as the mass of 1 cm3 of
water at 4 0C.
• 1000g = 1000 cm3 of water
• 1kg = 1L of water
Converting
k h D
d c m
• how far you have to move on this chart,
tells you how far, and which direction to
move the decimal place.
• The box is the base unit, meters, Liters,
grams, etc.
Conversions
k h D
d c m
• Change 5.6 m to millimeters
starts
at the base unit and move three to
the right.
move the decimal point three to the right
56 00
Conversions
k h D
d c m
• convert 25 mg to grams
• convert 0.45 km to mm
• convert 35 mL to liters
• It works because the math works, we
are dividing or multiplying by 10 the
correct number of times
Conversions
k h D

d c m
Change 5.6 km to millimeters
Which is heavier?
it depends
Density
• How heavy something is for its size
• The ratio of mass to volume for a
substance
• D = M/V
• Independent of how much of it you have
• Gold- high density
• Air- low density
Calculating
• The formula tells you how
• Units will be g/ml or g/cm3
• A piece of wood has a mass of 11.2g and
a volume of 23mL. What is the density?
• A piece of wood has a density of 0.93
g/mL and a volume of 23 mL what is the
mass?
Floating
• Lower density floats on higher density
• Ice is less dense than water
• Most wood is less dense than water
• Helium is less dense than air.
• A ship is less dense than water
Density of Water
• 1g of water is 1mL of water
• Density of water is 1 g/mL
• At 40C
• Otherwise it is less
0ºC
Measuring Temperature
• Celsius scale.
• water freezes at 0ºC
• water boils at 100ºC
• body temperature 37ºC
• room temperature 20 - 25ºC
273 K Measuring
Temperature
• Kelvin starts at absolute zero (-273 º C)
• degrees are the same size
• C = K -273
• K = C + 273
• Kelvin is always bigger.
• Kelvin can never be negative.
Temperature
• A measure of the average kinetic energy
• Different temperature scales, all are
talking about the same height of mercury.
• Derive a equation for converting ºF toºC
Calculating Temp.
•
•
•
•
•
I.
II.
From Celsius to Fahrenheit
F= (C x 9/5) + 32
From Fahrenheit to Celsius
C= 5/9 (F-32)
Examples:
49 0F to 0C
97 0C to 0F
Converting Kelvin
• Converting Kelvin to Celsius
• K = C + 273
• Converting Celsius to Kelvin
• C = K – 273
• Why is there no conversion from Kelvin to
Fahrenheit?
Problems
•
1.
2.
3.
4.
How many????
349K to 0C
120C to K
340F to 0C
1010C to 0F
Temperature is different
• from heat.
• Temperature is which way heat will flow.
(from hot to cold)
• Heat is energy, ability to do work.
• A drop of boiling water hurts,
• kilogram of boiling water kills.