Chapter 1.1 Discussion: Lab Safety Lab Safety Contract

Chapter 1.2

Scientific method – an established set of principles that scientists use as a logical, organized method of study Scientific Method – Ensures that investigations are Consistent Universally understood Repeatable Scientific method is not necessarily a linear list of steps – Process of cycles and repeating steps

Create a hypothesis – Best answer to your question – Hypothesis – possible and testable explanation based on an educated guess Formulating a hypothesis – Often an “if/then” statement – If [intended change of the independent variable], then [expected result on the dependent variable] Scientific Method

Observation – the information that is collected by using one or more of the five senses Many tools also aid in observation – Ex) Telescope Hypothesis

Observation is the first step in making a scientific inquiry – Observations lead to a hypothesis Hypothesis – a proposed explanation for a set of observations or natural phenomena – Educated guess or prediction based on other scientific data or knowledge – Must be testable – Must be falsifiable – Not limited to science Hypothesis

Ex) “What is the effect of studying time on exam grades?” – Possible testable hypothesis “If the amount of studying time for an exam increased, then the grade received on the exam will increase.” Using an “if/then” statement highlights cause and effect Scientific Method

Design and perform an experiment that supports or rejects your hypothesis – Select appropriate equipment and technology Available and accessible Experiment may need to be modified based on equipment availability Consider all necessary items to complete the experiment Scientific Method

Experiments should provide meaningful data – Collect accurate, precise, and unbiased data – Perform multiple trials – Consider reasonability of data Compare with expected values – Draw conclusions that support or refute hypothesis If results are inconclusive, conduct more experiments Scientific Method

Scientific theory – an explanation for a set of observations or natural phenomena that have been repeatedly confirmed through experimentation and observations Theories – Broad in nature – Supported by considerable evidence – Generated over a long period of time – Capable of being tested by multiple independent researchers – Observations can lead to theories – Describe an observed pattern – Describe the mechanism responsible for pattern

Ex) Theory of evolution – all living organisms on Earth share a common ancestor and they have changed over time through natural selection – Describes a set of observations – Describes the process by which evolution occurs – Tested by multiple independent researchers Theories

Theories can change – If results are contradictory to the theory – Technological advancement Theories can be modified or rejected Scientific advancement relies on the opportunity for change in scientific theories Scientific theories are supported by a considerable amount of evidence collected over a long period of time Theories

Scientific law – a law that states a repeated observation of a behavior or phenomena – Scientific theories provide general explanation for set of observations – Scientific law is a statement about an observation – Ex) Isaac Newton’s law of gravity predicts the movement of objects, but does not explain how or why gravity works Theories

Scientific fact – an observation that has been confirmed repeatedly and accepted as truth – Must be repeatedly confirmed and objective Scientific facts, laws, and hypotheses help generate and formulate scientific theories Theories

Chapter 1.3

Precision – a description of the level of exactness of a measurement – Related to the tool used to make the measurement Accuracy – a description of how close a measurement is to the standard or correct value – Measurements can be precise and not accurate – Ex) A package known to contain 125 g of lead is weighed by a scale that reads g Calibration issue with the scale Some lead from the package did not get measured Accuracy & Precision

All measurements have some level of uncertainty – Limitations of instrument – Experimenter using the instrument Human error is a common source of uncertainty – Limit human error in experiments Accuracy & Precision

Scientific notation – a method of expressing numbers as a value between one and ten (A) multiplied by a whole number power of ten (n) – Used to express very large or very small numbers Power of ten represents the number of places the decimal point was moved – Large numbers have positive n – Small numbers have negative n Scientific Notation

Ex) Large numbers displayed in scientific notation Scientific Notation Standard FormScientific Notation 233,432,875,880,000, × ,238,900,000, × ,689,000,000,000, × ,800, × 10 8

Ex) Small numbers displayed in scientific notation Scientific Notation Standard FormScientific Notation × × × ×

International System of Units (SI units) – a set of standard units of measure for the fundamental quantities of science – Created in 1960 Seven SI base units used in science SI Units QuantityUnitSymbol Lengthmeterm Masskilogramkg Timeseconds TemperaturekelvinK

SI prefixes can be added to a base unit to indicate very small or large measurements – Ex) 1 kilometer is equal to 1000 meters SI Units PrefixSymbolMultiplication Factor giga-G1,000,000, mega-M1,000, kilo-k1, hecto-h deka-da deci-d centi-c milli-m micro- μ

Dimensional analysis – a problem-solving method that determines relationships between quantities by using their units Dimensional Analysis Length 1 in = 2.54 cm 1 ft = 12 in 1 mi = 5280 ft Mass 1 kg = lb 1 lb = 16 oz Time 1 min = 60 s 1 hr = 60 min 1 day = 24 hr Volume 1 cm 3 = 1 mL = 1 cc 1 m 3 = 1000 L Energy 1 cal = 4.18 J 1 Cal = 1kcal = 1000 cal Pressure 1 atm = 760 mm Hg = kPa – Conversion factor – a mathematical ratio between two different units that measure the same quantity