Intoduction

NASA, ESA, S. Wyithe (University of Melbourne), H. Yan (Ohio State University), R. Windhorst (Arizona State University), and S. Mao (Jodrell Bank Center for Astrophysics, and National Astronomical Observatories of China)

Endeavor to discover how nature works and to use that knowledge to make predictions about what is likely to happen in nature.

Science is a discipline that attempts to describe the natural world in terms of order. Biology Chemistry Physics Earth Science

1. To conclude from evidence or premises

2. To reason from circumstance; surmise: We can infer that his motive in publishing the diary was less than honorable

3. To lead to as a consequence or conclusion: “Socrates argued that a statue inferred the existence of a sculptor”

HYPOTHESIS – proposed to explain observed patterns

Critical experimentsAnalysis and conclusions

What is the question to be answered?What relevant facts and data are

known?What new data should be collected?After collection, can it be used to

make a law?What hypothesis can be invented to

explain this? How can it become a theory?

Scientific Theory A hypothesis that has been supported

by multiple scientists’ experiments in multiple locations

A Scientific Law a description of what we find

happening in nature over and over again in a certain way

Law of Conservation of Matter Matter can be changed from one form to

another, but never created or destroyed.Atomic Theory of Matter

All matter is made of atoms which cannot be destroyed, created, or subdivided.

Inductive Reasoning Uses observations and facts to arrive

at hypotheses All mammals breathe oxygen.

Deductive Reasoning Uses logic to arrive at a specific

conclusion based on a generalization All birds have feathers, Eagles are

birds, therefore All eagles have feathers.

Frontier Science Scientific “breakthroughs” and

controversial data that has not been widely tested or accepted

String Theory Consensus or Applied Science

Consists of data, theories, and laws that are widely accepted by scientists considered experts in the field involved

Human Genome Project

Scientists use models to imitate the system. Mice are used to determine LD50

Chemists use structural models when investigating a chemical

Remember the plum pudding! Mathematical and computer models are

able to predict many outcomes

Factors represent the variables in a scientific theory The factors that are involved in a theory

about why you are late to my class▪ your walking speed▪ interference by your peers▪ the distance from point A to my room

Always makes observations.Always questions.Always using good scientific

practices to record and analyze data.

Repeats trials Uses statistics to analyze data Uses safe and accepted practices Uses data to support hypotheses

Variables are what affect processes in the experiment.

Controlled experiments have only one variable

Experimental group gets the variable Control group does not have the variable

Placebo is a harmless pill that resembles the pill being tested.

In double blind experiments, neither the patient nor the doctors know who is the control or experiment group.

A variable is a source or variance in an experiment and include independent and dependent variables. Independent variable (x-axis): the variable

which is changed in an experiment.

Dependent variable (y-axis): the variable which is measured in an experiment.

A review and practice

Qualitative data describes the physical properties of matter in terms of a description, not a measurement. Ex. Red ball, blue balloon

Quantitative data describes the physical properties of matter in terms of a measured or counted quantity Ex. 25 eggs, 35.2 grams

Measurement is determining the size or magnitude of something using a device or accepted value. All measurements have magnitude, Units, and Uncertainty

Counting is never uncertain unless you estimate a very large number- counting is not a measurement Exact numbers are obtained by counting

or definition

devices have a limit on precisionzero a balance or correct for a

measuring devicesignificant digits are part of a valid

measurement depending on the divisions

• All measurements have a certain degree of uncertainty, because of instrument calibration and human bias.• Measurements should be made recording all certain

digits plus one estimated digit.

Always read the volume of a liquid at the bottom of the meniscus

5040302010

Errors in chemistry are classified as systematic (determinate) and random (indeterminate). Error - the result of a measurement minus a

true value of the measure and (physical paramater being quantified by measurement)

Systematic Error – an error that can be identified and is repeated

Random Error – an error that occurs due to irreproducible conditions.

accuracy is how well a measurement agrees with the true value poor accuracy means poor equipment or

flaw in procedures relates to a chemical measure, qualitative

concept The error of an observation is the

difference between the observation and the actual or true value of the quantity observed.

precision is how well a measuring device can reproduce a measurement The term precision is used in describing the

agreement of a set of results among themselves. Precision is usually expressed in terms of the deviation of a set of results from the arithmetic mean of the set

devices have a limit on precision; precise measurements that are not accurate indicate an equipment error; zero a balance or correct for a measuring device

poor precision means poor technique

Percentage error is used to determine how far from the true value Take the absolute value of the difference in

the accepted value and the experimental value divided by the accepted or true value

Put the number into % form; Low % error indicates accuracy

% Error = 100 – percent correct▪ Percent correct = number correct / total

Scientific Notation is a way to express very large or very small numbers. Scientific notation expresses numbers as

a multiple of two factors: a number between 1 and 9; and ten raised to a power, or exponent.

The exponent is the magnitude of the number of places you move the decimal.

When you decrease the exponent, you move the decimal to the left; increase moves to the right.

Convert the following to scientific notation and then count the significant figures:

• 1,392,000 g

• 0.000 000 028 km

• 0.000 000 000 000 050 ms

• 472,920,000,000,000,000 mmol

Multiplication: add the exponents (5.0 x 103) x (2.0 x 102)

Division: subtract the exponents (6.0 x 103) ÷ (2.0 x 102)

Addition/Subtraction: exponents must be the same before you perform the function (1.50 x 102) + (3.45 x 103)

Mega 1,000,000 Kilo 1,000 Hecto 100 Deka 10 Base 1 Deci 0.1 Centi 0.01 Milli 0.001 Micro 0.000 001 Nano 0.000 000 001 Pico 0.000 000 000 001

Each new unit is a factor of 1,000 less from this point on

There is a factor of 1,000 between these two prefixes

1 million = 1 x 106

1 billion = 1 x 109

1 trillion = 1 x 1012

A percentage is a ratio of 1005% is 0.05 x 100What is 3.5% of 1,999,220?What percentage of animals is 255

out of 3420?

The Greek alphabet is still used today to represent quantities and constants in physics, chemistry, economics, statistics . . .

Using the measuring tools

In Chemistry, the temperature scale utilized is the Kelvin Scale K = C + 273.15 So, 100oC = 373 K

Fahrenheit and Celsius Conversions oC = (oF – 32) x 5/9 oF = (oC x 9/5 ) + 32

Of a rectangular prism or cube may be calculated by using the following formula: v=lwh

Of a cylinder may be calculated using the following formula:

Of a cone may be calculated using the following formula:

Of odd shaped objects: may be measured by the amount of water displaced when the objected is added to it

In order to measure the volume of an irregular object, use the displacement method. 1: using a graduated cylinder, measure and

record the volume of water. 2: place the object in the graduated cylinder so

that it is completely submerged, but the water doesn’t overflow

3: measure and record the new volume of water. 4: subtract the initial volume from the final

volume. This is the volume of the object in mL▪ 1 mL = 1 cm3

Density is a derived unit that describes the ratio between both the mass and volume of matter. D = m / v

• What is the density of an object with a mass of 85.6 g and a volume of 17.99 mL?

The density of tin is 7.265 g/mL. If a sample of tin has a mass of 13.6 g what is its volume?

A useful tool to solve many problems u known x conversion factor = answer Conversion factors are equivalents like

▪ 1 dozen eggs = 12 each eggs▪ It is set up with the unknown number with unit

divided by the known number with unit If you have 2.35 kg of a sample

whose density is 1.25 g/mL, how many Liters of sample do you have?

Astronomical Units (AU): based on Earth’s average distance from the Sun. Used only for objects and distances within our solar system. 1 AU = 149,597,871 km

Light Year (ly): the distance light travels in one Earth year 1 ly = 9.461 x 1012 km So how long does it take for light to reach the

earth in years? How about days? Now hours? What about minutes?

A graph relates two variables from an experiment. One of the variables is changed in order to study how it affects the other variable.

The variable that is manipulated by the experimenter is called the independent variable and it’s values are plotted on the ‘x’ or horizontal axis.

The variable whose values are determined by the results of the experiment is called the dependent variable and is plotted on the ‘y’ or vertical axis.

Each axis must have a numbered scale to show the values of each variable.

The scale should begin with a number slightly less than the lowest value and extend to a number slightly more than the greatest value and designed to occupy the majority of the paper.

The scale must be uniform. That is each block on the graph must represent the same amount as any other block of that scale.

Scales do not necessarily need to begin at zero. The two scales do not necessarily need to match.

Each axis must have a label which states the variable which is plotted on the axis.

Each axis must indicate the unit used to measure the variable.

Use a small uniform dot to plot each point in it’s proper position.

A small circle is drawn around each dot. The purpose of the circle is to represent the uncertainty in the measurements of that set of data.

In more advanced classes you may be asked to calculate the uncertainty of the measurements and to draw a circle that precisely represents that uncertainty.

The points on the graph should be neatly connected to show the trend in the data. How the points are connected depends upon what kind of data was collected.

Discrete data (counted items) are connected point-to-point by straight lines.

Continuous data (measured quantities) are connected by a smooth line which may be straight or curved. The line does not need to touch each circle as it only shows the trend in the data.

Each graph should have a title placed in some clear area, usually near the top of the paper.

The title should be informative. That means that it should relate to the reader information about the experiment that is not part of the graph without the title.

Various amounts of table salt are added to water and the boiling point of the solution is measured with a thermometer.

Grams of NaCl Boiling Point 0g 100.0oC 2g 103.1oC 4g 107.0oC 6g 107.9oC 8g 108.7oC 10g 109.5oC

1. Assign variables to the proper axis.

2. Set-up the scales.

The Graph

0 1 2 3 4 5 6 7 8 9 10 11

100

115

110

105

3. Label each axis.

Mass of NaCl in grams

Tem

pera

ture

in o

C

The Graph

100

105

110

115

4. Plot and circle the points.

The Graph

Mass of NaCl in grams

Tem

pera

ture

in o

C

0 1 2 3 4 5 6 7 8 9 10 11

..

. . . .

100

105

110

115

5. Connect the points.

Mass of NaCl in grams

Tem

pera

ture

in o

C

0 1 2 3 4 5 6 7 8 9 10 11

..

. . . .

100

105

110

115

6. Title the graph.

Mass of NaCl in grams

Tem

pera

ture

in o

C

0 1 2 3 4 5 6 7 8 9 10 11

The Boiling Point of Salt Solutions

..

. . . .

100

105

110

115

Measure out 1,2,3,4 and 5-mL volumes of water.

Weigh each volume and record. Plot the mass versus the volume

Which variable did you change? Which variable did you measure? Which variable is the

independent/dependent? Plot your data by hand on a piece of graph

paper