# C3: Key Concepts in Physical Science Physical Science.

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C3: Key Concepts in Physical Science Physical Science

C3: Key Concepts in Physical Science Supplies: Pencil Standards: – 3b) Compounds are formed by combining two or more different elements and that compounds have properties that are different from their constituent elements – 3d) States of matter depend on molecular motion – 3e) In solids the atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; in gases the atoms and molecules are free to move independently, colliding frequently

C3 Key Concepts in Physical Science You will be taking notes using Cornell Notes format or Charting Notes format.

C3.1 Mass and the Atomic Theory of Matter Definitions Kilogram (kg): the basic metric (SI) unit of mass Gram (g): a unit of mass smaller than a kilogram. One kg equals 1000 g. Atom: the smallest particle of matter that retains the identity of the element, such as an atom of gold. Element: a pure substance that cannot be broken down into other elements

Mass and the Atomic Theory of Matter Mass is the amount of matter in and object. It is not weight -- Weight is the effect of gravity on mass. Matter is made up of atoms (more on that later) Atoms of different elements have a different mass - so 10,000 atoms of iron have a different mass than 10,000 atoms of sodium.

Kilograms Mass is measured inkilograms (1000 grams) – 1 bunch of bananas – 1 liter of soda – 1/5 of a cat – 1/50 of an 8th grader Exactly one liter of water Platinum-Iridium alloystored in SI office in France

Measuring Mass Use a balance Compare the mass youhave to a known mass Zero balance beforepulling mass on it

Atoms and Elements An atom is the smallest piece of an element you can have How big is a atom? Aluminum foil is about 200,000 atoms thick An element is a pure substance that cannot be broken down into other substances 92 naturally occurring makes up most of what you see and touch.

Compounds Compounds are made of two or moreelements -- e.g. NaCl Properties of compounds are differentthan the properties of the atoms thatmake them up. If we take two compounds apart andrearrange them, the properties will bedifferent. You don’t usually find pure elementsin nature

Chemical Reactions Chemical reactionsrearrange atoms from twoor more compounds Atoms move from onecompound to the other e.g.iron + oxygen  rust Different combination ofatoms means a differentsubstance

Solids, Liquids, Gas Solid - – atoms attached toneighbor – Vibrate in place Liquid – Atoms temporarilybreak attachmentswith neighbors Gas – atoms are not attachedto neighbors

C3.2 Temperature and Energy Definitions System: a small group of related things that work together Energy: a quantity that measures the ability to causechange in the physical system. Energy is measured injoules. Force: a push, pull, or any action which has the ability tochange motion. Force is measured in newtons. Newton (N): the unit of force in the metric (SI) system. Joule (J): the unit of energy in the metric (SI) system. Onejoule is enough energy to push with a force of one newtonfor a distance of one meter.

C3.2 Temperature and Energy Temperature: a measurement of hot or cold thatdepends on the thermal energy in a material. Thermometer: an instrument used to measuretemperature. Fahrenheit scale: temperature scale in whichwater freezes at 32 degrees and boils at 212degrees. Celsius scale: temperature scale in which waterfreezes at 0 degrees and boils at 100 degrees. Absolute zero: the lowest temperature there canbe, equal to -273.3°C or -460°F.

C3.2 Temperature and Energy Thermal energy: energy that is due to differencein temperature. Thermal energy comes fromkinetic energy of individual atoms. Heat: thermal energy that is moving. Calorie: a unit of energy equal to 4.184 joules orthe energy needed to heat 1 gram of water by1°C. Specific heat: a material property that tells howmuch energy is needed to change thetemperature by one degree.

Energy Atoms are alwaysmoving (except atabsolute 0 K) Movement meansenergy Movement meanstemperature

System A system is a small group of related things that work together Break things down into systems to make them understandableparts Parts of a system interact by exchanging energy: e.g. the coffeeand the cup

Force A push or a pull Force is measured innewtons (N) More on that in a laterchapter.

Energy Parts of a systeminteract with each otherby exchanging energy Energy causes changesin temperature, speed,position, mass, etc. Energy is measured injoules (J): the amount ofenergy to push with oneNewton for one meter.

Potential and Kinetic Potential energy - storedability to create force,due to position orarrangement, e.g.gravitational, elastic,chemical Kinetic energy - energyof motion

Temperature - Measurement of Heat Fahrenheit – 1714 Gabriel Fahrenheit – 0 ºF was the coldest he could get anything – Water freezes at 32 ºF – Water boils at 212 ºF Celsius – 1742 Anders Celsius – Water freezes a 0ºC – Water boils at 100 ºC Kelvin – Absolute zero (0K) is the coldest anything can get – Water freezes at 273.15 K – Water boils at 373.15 K

Converting Between Temperature Scales T fahreneheit = (9/5)T celsius + 32 T celsius = (5/9)(T fahrenheit - 32) T kelvin = T celsius + 273.15

Temperature Extremes Minimum temperature -- Absolute zero: 0K, -273  C, -459  F No maximum temperature, 10,000  C atoms break apart and form plasma, positive and negative ions (more on that in a later chapter) Solar system temperature range -270  C (between outer planets) to 15,000,000  C (center of sun) Earth temperature range -89  C (-129  F) to 58  C (136  F)

Thermal Energy Temperature measuresthermal energy Thermal energy that isflowing is called heat. Itmoves from a hightemperature object to a lowtemperature object. It is measured in calories(4.184 Joules) What you eat arekilocalories [C].

Specific Heat How long it takes to heat something depends on the mass Different elements require different amounts of energy to change temperature Specific heat is the energy it takes to raise the temperature of one kilogram by 1ºC A high specific heat means the temperature of a substance changes slowly.

Conservation of Energy Energy cannot be created ordestroyed just by changingfrom one form into another. PG&E does not makeelectricity. They convert oneform of energy to electricalenergy. Energy of falling transferredto heat of collision.Basketballs get warm whenyou dribble them.

Energy Conservation We are converting energy toelectricity which is easy tomove through copper wire Electricity is converted toheat, light, etc. We will not run out ofenergy -- we will run out ofenergy in a form we caneasily use. Trivial picture of tree, windmill, and sunset