CRCT/EOCT Review: Physical Science
Scientific Processes: Observations, Questions, and Hypotheses
Observation / Scientific Questions / HypothesisMoss grows only in shady areas. / Does moss grow better in shade or sunlight? / Direct sunlight inhibits moss growth.
Hypothesis: a possible answer to a scientific question. Experiment: a procedure designed to test a hypothesis.
Independent and Dependent Variables
Question / Independent Variable / Dependent VariableWhich fertilizer grows the largest oranges? / Type of fertilizer / Size of oranges
A Variable is any factor that can affect the results of an experiment.
Independent Variables are manipulated or controlled by the experimenter.
Dependent Variables respond to changes in the independent variables.
Control and Experimental Groups
Control Group / Experimental GroupDefinition / Standard setup used to compare the experimental results / Same conditions as control, except for a change in the variable being tested
Variables / Variables NOT manipulated / Only tested variable changed
Example / Four eggs put in an incubator at 29˚ C, 70% humidity, in low light / Identical conditions as the control group, but temperature is 35˚ C
The Control Group represents the norm and shows what would happen when nothing is changed. No variables are altered.
The Experimental Group has conditions identical to those of the control group except for the one variable being altered and studied.
SI Base Units
Measurement / Definition / Metric Base Unit / SymbolLength or Distance / a measure of the distance between two points / meter / m
Mass / the measure of the amount of matter making up an object and is measured with a balance. / gram or kilogram / g or kg
Volume (liquid) / the amount of space matter occupies.
Liquid volume is usually measured in milliliters (mL) or liters (L) using a graduated cylinder.
Volume for a solid with a regular shape is calculated using the formula: volume = length x width x height / liter / L
Force (weight) / a measure of the pull of gravity on an object and is measured with a Spring Scale (used to measure weight and forces). / Newton * / N
Temperature / a measure of the average kinetic energy of the particles in a sample of matter and is measured with a thermometer. / Kelvin * / K
Time / a measure of increments of the day. / second / s
*Remember that units named after a dead dude (or a living dude) are capitalized.
Common SI Prefixes
Prefix / Meaning / Decimal Equivalentm milli- / one-thousandth (1/1000) / 0.001
c centi- / one-hundredth (1/100) / 0.01
k kilo- / one thousand (1,000) / 1,000
M Mega- / one million (1,000,000) / 1,000,000
To change from one prefix to another – remember khda_dcm or King Henry Died while Drinking Chocolate Milk
How do I convert 200 kg to g? Break down the information: 200kg = 200.0 kilo grams. You need to change this to grams.
1. Start with what you know. 200 kg “k” is for the prefix kilo, and “g” is for the unit grams (kg=kilograms) Go to “kilo”
2. Find what you are trying to change to. g “g” is just “unit”, there is no prefix. One letter by itself is always “unit”
3. To get from where you started to what you needed to change to,
in which direction did you move? From kilo to unit is to the RIGHT
4. How many places did you move? Don’t count the one you’re on. 3 hecto, deca, unit – 3 spots.
5. Move your decimal the same number of places and in the same direction – 3 spots to the right.
6. Make your places and fill in your “soup bowls” with new 0’s. 200.0 kg = 200000.0 g
Measurement Formed from Derived Units
Measurement / Derived Units / SymbolSpeed / meters per second / m/s
Density / liquid: grams per liter or grams per milliliter
solid: kilograms per cubic meter or grams per cubic centimeter / g/L or g/mL
kg/m³ or g/cm³
Volume (solid) / cubic meters or cubic centimeters / m³ or cm³
Mathematical Terms
Range: difference between the highest and lowest values in the data.
Mean: average value.
Median: number that falls exactly in the middle of a set of data when the data are arranged in order from least to greatest.
Mode: in a set of data is the number that appears most often
To help you remember: Hey diddle diddle, the median’s the middle,
You add then divide for the mean.
The mode is the one that you see the most,
And the range is the difference between.
Laws of Conservation
The Law of Conservation of “ABC” states that, in a closed system, “ABC” can neither be created nor destroyed, but it can be transformed.
So, the Law of Conservation of Matter states that Matter can not be created nor destroyed, but can be changed.
The Law of Conservation of Energy states that Energy can not be created nor destroyed, but can be changed.
This is why we have to make sure that equations are balanced – what we start with is what we end with.
Also why we have to be sure to account for friction/thermal energy when talking about energy conversions.
You’ve got to know where it all went.
Matter
Everything is made of matter. Matter is anything with mass and volume.
Can be classified with Physical or Chemical Properties. See below.
Difference between mass and weight
Weight – affect of gravity on a mass, measured in Newtons (N) with a scale
Mass – amount of matter, measured in grams/kilograms (g or kg) with a balance
Inertia – tendency of an object at rest to stay at rest, in motion to stay in motion at a constant velocity
The greater the masses the greater the gravity, closer the distance the greater the gravity.
Distinguish between physical and chemical properties
Physical Properties – observed or measured w/o changing the identity of the matter – most properties, color, texture, volume,
odor, Density (D=mass/volume), state, malleability/ductility, melting point, boiling point
Chemical Properties - describes how a substance will interact with another during a chemical reaction
Primarily are reactivity, flammability, combustibility aka Fire, Boom, React
Distinguish between physical and chemical changes
Physical Change – change of state or shape, no change in the identity of the object - frozen water (ice) is still water. Ripped paper is still paper.
Chemical Reaction is the process by which new substances are formed during a chemical change.
Signs that indicate a chemical reaction/change has occurred include:
the forming of gases or bubbles,
a change in color,
the release of heat,
or the emission of light or an odor For an example, sugar, eggs, etc à cake changes color, smells, bubbles
Distinguish between atoms and molecules
Atom – smallest particle into which an element can be divided and still be the same substance. Building blocks of ALL matter.
Characteristics of Subatomic (parts of the atom) Particles
Particle / Electric Charge / Symbol / Mass / Location in AtomProton / Positive “positive permanent protons” / + / 1 amu / Nucleus
Neutron / Neutral “neutral neutrons, neutral neutrons” / ± or Often not identified with a symbol / 1 amu / Nucleus
Electron / Negative / - / 0 / Electron Cloud
Nucleus: the center of an atom where you find protons and neutrons.
Atomic Number: the number of protons in the nucleus of an atom.
Atomic Mass of an atom is equal to the number of protons plus the number of neutrons in the atom’s nucleus.
Atomic Masses of Some Common Elements
Element / Protons / Neutrons / Electrons / Atomic Mass = protons + neutronsCarbon (C) / 6 / 6 / 6 / 12 amu
Sodium (Na) / 11 / 11 / 11 / 22 amu
Iron (Fe) / 26 / 29 / 26 / 55 amu
How to find:
Protons – same as the Atomic Number of the element
Electrons – same as the number of protons in a neutral atom (an atom that has no charge because + and – are equal)
Neutrons – subtract the atomic number from the atomic mass. See Fe above. 55-26 = 29
Molecules – smallest unit of a covalent compound (shared electrons) that has all the properties of that compound.
Diatomic molecules – H2, O2, N2, Cl2, etc.
Other molecules - C6H12O6, N2O, NaCl, CO2 6, 12, and 2 are examples of subscripts
Describe the difference between pure substances (elements and compounds) and mixtures
Pure substance – a substance in which there is only one type of particle (element or compound) throughout.
Element – can not be broken/separated into simpler substance, classified into metals, nonmetals, metalloids
Compounds – pure sub made of 2+ elements that are chemically combined in a definite ratio – H2O, NaCl, C6H12O6, CO2
Can be broken down into simpler substances via chemical means, not by physical means
Mixtures – combo of 2+ sub NOT chemically combined, can be physically separated, components retain ID, no ratio
Can be separated via distillation, centrifuge, magnet, filtering, evaporation
Types of Mixtures – can be homogeneous (same throughout) or heterogeneous (you can see different parts)
MatterPure Substance / Mixture
Element
Can not be broken down further
Found on the Periodic Table / Compound
2 or more elements that have been chemically combined / Homogeneous
Looks the same all the way throughout the sample / Heterogeneous
You can see the different ingredients. Not the same.
Solutions / Colloids / Suspensions
Solutions = Solute + Solvent / Colloids / Suspensions
Particle size? / Small / Medium / Large
Can it be filtered apart? / No / No / Yes
Do the particles settle out to the bottom? / No / No / Yes
Light reaction? / Light goes right through.
Solutions appear clear. / You can see the beam of light.
Colloids tend to look cloudy. / You can see the chunks of stuff floating around. Will settle to bottom unless stirred.
Examples? / Clear Gatorade
Sugar Water / Whipped Cream
Clouds / Snow Globes
Italian Salad Dressing
Other Vocabulary
Solute – sub that is dissolved eg. Sugar
Solvent – sub that does the dissolving eg. Water Remember the Ice cream cone “V”
Solubility – how easily dissolved
Concentration – how much solute is dissolved in the solvent. A lot = concentrated A little = diluted
Saturated - the solution has all the solute it can dissolve
Supersaturated – you’ve heated the solution so that it will take a little more, but the solute will recrystallize when cooled again.
Describe the movement of particles in solids, liquids, gases and plasma states
States of Matter and Their Properties
Property / Solid / Liquid / Gas / PlasmaShape / Definite shape / No definite shape –
takes shape of container / No definite shape –
takes shape of container / No definite shape –
takes shape of container
Volume – amount of space it takes up / Definite volume / Definite volume / No definite volume – takes vol. of container / No definite volume –
takes vol. of container
Particle Arrangement / Densely packed / Close / Far apart / Far apart
Energy Binding the Particles / Very strong / Strong / Weak / Weak – particles broken
Particle movement / Vibrate in place / Slide past each other / Fly apart / Fly apart
Amount of Energy / Low / Medium / High / VERY high
Analyze energy transfer associated with phase change
Endothermic - gaining energy --à-gets warmer------melting------vaporization------àwarmest
Name of state or phase – Solid Liquid Gas
coldest ßß------freezing------condensation------ßßgets colder – Exothermic – loses energy
Each substance has its own freezing and boiling points.
WATER = Freezing/Melting 0°C = 32°F = 273K
Condensation/Boiling 100°C = 212°F = 373K
Sublimation – Solid changes directly to a gas
Boiling Point: the temperature at which a liquid begins vaporizing or changing to a gas.
Freezing Point: the temperature at which a liquid begins to change into a solid.
Melting Point is the temperature at which a solid substance melts to form a liquid.
Boiling – change of state all throughout the substance
Evaporation – change of state at the surface, doesn’t have to be at the boiling point, just has to have gained energy.
Investigate the arrangement of the Periodic Table –
Periodic Table is a chart that organizes information about all of the known elements according to their properties.
Periods are horizontal rows that are numbered from 1 to 7 and are arranged in order of increasing atomic number. “Long sentences end in a .”
Groups or Families are vertical columns and are numbered from 1 to 18, as well as 1A to 8A, and are elements that have similar chemical properties. “Families stand up for each other.”
Metals are found on the far left of the table.
Metalloids (elements that have some properties of both metals and nonmetals) follow metals.
Nonmetals are located on the far right-side of the table.
Classify elements as metals, nonmetals or metalloids using the Periodic Table – left metals, right nonmetals, stairs ‘loids
Properties of Metals and Nonmetals
Properties of Metals / Properties of NonmetalsSolid at room temperature, except mercury, which is a liquid / Most are gases, except bromine, which is a liquid
Malleable and ductile – can be shaped/flattened and drawn into wire / Are brittle in the solid phase
Have luster – are shiny / Have a tendency to be dull, not shiny or bright
Have high conductivity – are good conductors of electricity and heat / Are poor conductors of heat and electricity
Tend to lose electrons in chemical reactions / Tend to gain electrons in chemical reactions
Use the Periodic Table of Elements to gather information about an element –
Use the Periodic Table to explain the similarities and differences between elements
Know how to read the table’s squares to find Atomic Number, Atomic Mass, Chemical Symbol. See above for other info.
Group/Family number tells you how many valence electrons. Group 1 = 1 electron, Group 13 = 3 electrons