What is Science?

• Science is what scientists do

• Science is trying to explain the world around us

• “Science is a system of knowledge based on facts or principles”

• Science is a way of thinking

BiologicalScience

EarthScience

PhysicalScience

Branches of Science

Science of matter and energy

Science

Chemistry

Physics

Science and Technology

• Pure Science - search for scientific knowledge

• Technology – application of science

• Two are interrelated

• Technology develops new tools for investigating nature

• New science leads to new applications

Scientific Theory• A reasoned explanation tested by

many observations and experiments

• Tells why things are• Three things

– Must explain clearly and simply– Must be repeatable– Must be able to make predictions

• Theories can be changed or modified by new evidence

Scientific Law

•Describe what happens• Quantitative – use numbers and

equations to describe

• equations are often part of scientific law

• Mathematics is a universal language

Law Theory

Describes how Explains why

Summarizes observations

Agrees with observations

Usually an equation

Predicts new discoveries

Law vs. Theory

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• Models are made to better understand

things• Often used if real thing is too big, too

small or complex.

Models 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

• Starts with observation- can be anything• Question – what do you want to know?

• Gather data- what is already known• Form hypothesis- a possible explanation• Design experiment to test hypothesis

– This is the hard part

• Experiments generate

more observations• Allow us to draw conclusions about hypothesis–Support the hypothesis or not

–If the hypothesis is not supported then the hypothesis must be modified

The Scientific Method

Observe

Collectdata

Formhypothesis

Experimenttests hypothesis

Observation

Observation

Observation

Formulatea question

DrawConclusions

Tables• Organizing data into groups • Putting those groups into rows

and columns• Gives us an easy way to compare

data

Graphs• Give a visual representation of data• Summarizes data.Two types of variables:

–Independent variable the thing you have control over and is shown on the x-axis

–Dependent variable the thing that you don’t have control over and is shown on the y-axis

Circle Graphs

• Often called a pie chart

• divided into parts

• easy to compare to whole amount.

• Use several to show changes over time

Bar Graphs

• Bar Graphs- wide columns used things like weight, height , and length.

• Compare quantities

Line Graphs

• Line Graphs- compares sets of data, show change and patterns over time.

Graphs include• A title• Labeled axes• A consistent scale.

Axis is on the Horizontal and showsThe independent variable

Axis is on the verticalAnd shows the Dependent variable

Chemistry

• The study of matter and how it changes

• Matter – anything that has mass and takes up space

• Mass – resistance to change in motion

• Two types of matter-– Substance- Pure– Mixture- more than one substance

Pure Substance

• Elements and compounds

• Only one kind of molecule or atom

• Compounds have specific amounts of their elements

• Compounds are completely different from their elements

Mixture

• Different substances mixed together

• Can be in any proportion

• Keeps the same properties as the things that make it

• Kool-aid – Mix something sweet, something wet and

something red– Get something sweet, wet and red

Two Types of Mixtures

• Heterogeneous- – Different from place to place– Not evenly mixed– Chocolate chip cookie, gravel, soil

• Homogeneous-– The same throughout– Evenly mixed– Kool-aid, sea water, air

Liquid Mixtures

• Miscible-– Liquids that do dissolve in each other– Homogeneous– Gasoline

• Immiscible-– Liquids that don’t dissolve in each other– Heterogeneous– Oil and water

Kinetic Theory

• Kinetic means motion

• Three main parts of the theory– All matter is made of tiny particles– These particles are in constant motion and

the higher the temperature, the faster they move

– At the same temperature, heavier particles move slower.

States of Matter

• Solid

• Particles are tightly packed

• Stuck to each other in a pattern

• Vibrate in place

• Can’t flow

• Constant volume

States of Matter

• Liquid

• Particles are tightly packed

• Able to slide past each other

• Can flow

• Constant volume

States of Matter

• Gas

• Particles are spread out

• Flying all over the place

• Can flow

• Volume of whatevercontainer their in

Gases

• Fill the available space

• Particles moving at about 500 m/s

• Particles hitting things cause pressure

Volume

• Liter a common unit

• 1 mL is about 20 drops of water or 1 sugar cube

Density

• Found by dividing the mass by volume

• D = m V

• Units of g/mL or g/cm3

• Water has a density of 1 g/mL•Ratio of mass to volumeRatio of mass to volume

•If the density of substance is If the density of substance is less than its surroundings, it less than its surroundings, it floatsfloats

Density

D

M

V

Cover up the one you are looking for to find the formula for the missing piece

• A piece of wood has a massof 12 g and a volume of 16 cm3 What is its density?

• Steel has a density of 7.8 g/cm3. How much would 56 cm3 of steel weigh?

• What would the volume of the same mass of water be?

DensityMVD

Liquids

• Spread out on their own

• Fluids- gases and liquids both flow

• Viscosity- the resistance to flow

• The better the molecules stick to each other, the more resistance

Energy

• The ability change or move matter

• As you add energy to a liquid, the temperature goes up

• The molecules move faster

• Eventually they will move fast enough to break free and become a gas

• This is evaporation- the change from a liquid to gas

Phases Changes

• If you change rapidly enough, the gas will form below the surface an boil

• Condensation- Change from gas to liquid

• As you cool a gas the molecules slow down

• As gas molecules slow down they stick together

Phases Changes

• Molecules and atoms don’t change during a phase change

• the composition doesn’t change

• The mass doesn’t change

• The volume does change

• Only the attractions and motion change

Law of Conservation of Mass

• In all changes, mass cannot be created or destroyed

• All the mass you start with you end with

• It might be hard to count

Law of Conservation of Energy

• In all changes, energy cannot be created or destroyed

• All the energy you put in, you get out

• It might be hard to count

Properties

• A property is a something that describes matter– An adjective– Used to identify the matter– Used to distinguish between different types

Chemical Properties

• Used to describe how substance reacts

• How it changes– By combining with other substances– Or breaking apart

• Reactivity how a substance combines with other substances

• Things like flammability, rusting, etc.

Physical Properties

• Can be observed or measured without changing the composition

• Melting point , boiling point, hardness, odor, ability to conduct electricity and heat

• Density – how heavy something is for its size

• Allow us to identify substances

• Allow us to separate substances

• Determine uses

Properties

• Two types-– Physical Changes- no new type of matter is

made• All the molecules stay the same

– Chemical Change- a new type of matter is made

• Atoms rearrange to make new elements or compounds

Changes

• Completely new properties

• Products are not at all like the reactants

• Makes new odor, color, etc.

Chemical Changes

• Might look a little different

• Keeps original properties

• Changing phases

• Making a mixture

• Cutting

• Grinding

• Dissolving

Physical Changes

• Water molecules break apart and surround sugar molecules

• All the original molecules are still there

• Sugar gets so spread out that they don’t block light

Dissolving Sugar