GHSGT Review Physical Science

CHEMICAL CONCEPTS

Matter: anything that has mass and takes up space

pure substances mixtures

elements compounds homogeneous heterogeneous

one type of same more than solutions atom throughout one type of different atom parts are not held visible together by bonds

held together by bonds

mass- amount of matter in an object volume- the amount of space an object takes up

Density- mass divided by volume D=m/v Weight- mass times acceleration due to gravity W=mg g= 9.81m/s2

Type of properties What they describe Examples Physical Properties Describe what matter is Color, density, hardness, mass, (like an adjective) volume, boiling point, conductivity, malleability, melting point, odor, shape, weight

Chemical Properties Describe what matter does (like Reacts with oxygen, an adverb) Does not react with metals Ability to burn, ability to corrode, reactivity with light

Type of Changes Definition Examples Physical Change Does not create a new substance Cutting paper Phase changes Tearing paper Dissolving salt in water Chemical Change Creates a new substance Burning Rusting Temperature- the measure of how hot or cold something is Melting point – the point at which a substance changes from a solid to a liquid Boiling point- the point at which a substance changes from a liquid to a gas

Name Phases changed Heat transferred Melting Solid to liquid Heat gained (heated) Freezing Liquid to solid Heat lost (cooled) Vaporization Liquid to gas Heat gained (heated) Condensation Gas to liquid Heat lost (cooled) Sublimation Solid to gas Heat gained (heated)

ALL PHASE CHANGES ARE PHYSICAL CHANGES! Mixtures are separated by Physical Changes!

Chemical Changes- - makes a new substance - written as chemical equations - equations use symbols (for elements) and formulas (for compounds) - symbols for elements are found on the periodic table - reactants: the chemicals that do the reacting, the chemicals going into the reaction, written on the left of the arrow normally - products: the chemicals that are made during the reaction, the chemicals coming out of the reaction, written on the right of the arrow normally

Types of reactions: Synthesis- makes a single product, more than one reactant (on the left) only one product (on the right). Decomposition- breaking down a single reactant into multiple products, one reactant (on the left) more than one product (on the right) Single replacement- an element replaces another element in a compound, one element and a compound on the left, different element and compound on the right Double replacement- two compounds switch parts, two compounds on the left, two different compounds on the right

Evidence of Chemical Reactions 1. Color change 2. Gas produced 3. Precipitate 4. Light given off 5. Electric current produced 6. Temperature changes on its own

Endothermic- heat is taken in from the surroundings, the container of the reaction will feel cool or cold to the touch

Exothermic- heat is given off from the reaction, container of the reaction will feel warm or hot to the touch

Common Chemical Reactions 1. Combustion- Combining with oxygen rapidly 2. Rusting- combining with oxygen slowly 3. Neutralization- reaction between an acid and a base to form a salt and water 4. Fermentation- partial breakdown of sugars by yeasts to produce carbon dioxide and alcohol, in the absence of oxygen

Naming Ionic Compounds 1. Write the name of the positive ion without the word ion. 2. Write the name of the negative ion without the word ion.

Naming Covalent Compounds Prefix Number of Particular Element mono 1 di 2 tri 3 tetra 4 penta 5 hexa 6 hepta 7 octa 8

When a pair of elements form more than one type of covalent compound, Greek prefixes are used to indicate how many of each element are in a compound.

Some additional rules

 The prefix mono is never used for naming the first element of a compound.  The final "o" or "a" of a prefix is often dropped when the element begins with a vowel.

The element that comes first in the following list "goes" first.

B, Si, C, Sb, As, P, N, H, Te, Se, S, I, Br, Cl, O, F

H2O, which according to the rules should be called dihydrogen monoxide is always called water, and NH3, or nitrogen trihydride, is always called ammonia Naming Organic Compounds Prefix Number of Carbons Meth- 1 Eth- 2 Prop- 3 But- 4 Pent- 5 Hex- 6 Hept- 7 Oct- 8 Non- 9 Dec- 10

Suffixes All single bonds -ane A double bond -ene A triple bond -yne

Examples Methane, Ethane, Ethene, Ethyne

Writing Balanced Equations

Law of Conservation of Mass- Matter cannot be created nor destroyed it can only change forms - What goes in, must come out - Basis for Balancing equations These numbers are found in a chemical equation:

 Subscripts

The small numbers to the lower right of chemical symbols. Subscripts represent the number of atoms of each element in the molecule.

 Coefficients

The large numbers in front of chemical formulas. Coefficients represent the number of molecules of the substance in the reaction. The order in which the following steps are performed is important. While shortcuts are possible, following these steps in order is the best way to be sure you are correct.

Balancing Equations By Inspection

Types of Particles

Atoms- The smallest part of an element that can be identified as that element Compound- substance made up of two or more elements chemically combined (held together by bonds) Chemical bonds- force of attraction that hold atoms together (involves either sharing or transferring electrons)

All atoms want a full outer set of electrons. A full outer set consists of 8 electrons and is called an octet. Atoms form compounds to fill their outer set of electrons. For some atoms, such as metals, it is easier for them to give up their 1 or 2 electrons in the outer shell and fall back on the full shell beneath those electrons. For other atoms, such as Fluorine, Nitrogen, Oxygen, it is easier to take 1-3 electrons to fill their outer shell. Some atoms prefer to share electrons. Some will do both. The noble gases such as Argon and Neon already have a full outer set of electrons and do not react. Covalent Bonds- sharing electrons between two atoms Molecules- smallest particle of a covalent compound Ionic bonds- Transfer of electrons between two atoms Formula unit- smallest unit of an ionic compound

Ion- a charge particle formed by the loss or gain of electrons Cation- positively charged ion formed by losing one or more electrons Anion- negatively charged ion formed by gaining one or more electrons

Elements made up of atoms. Compounds made up of molecules (covalent) or ions ( ionic).

Atoms - made up of protons, neutrons, and electrons - has two regions: nucleus and electron cloud

Nucleus- dense center region of the atom, positively charged, contains protons and neutrons, contains nearly all the mass of the atom

Electron cloud- region around the nucleus where there is a good chance an electron might be found

Name Charge Relative Mass Location Proton +1 1 Nucleus Neutron 0 1 Nucleus Electron -1 0 Outside of Nucleus (electron cloud)

Atomic number- the number of protons in an atom - all atoms of an element have the same atomic number - the element an atom belongs to is determined by the atomic number - in a neutral atom (no charge) the number of electrons is the same as the atomic number

Mass number- The number of protons PLUS the number of neutrons in an atom

Calculating the number of neutrons in an atom:

Mass number – Atomic number= Number of neutrons

Mass number is found on the periodic table…. It is the number with the decimal. Atomic number is also found of the periodic table…. It is the whole number without a decimal.

Isotope- has the same number of protons but a DIFFERENT number of NEUTRONS. Isotope Carbon- 12 Carbon-14 Atomic Number (protons) 6 6 Mass Number (protons and 12 14 neutrons) Neutron Number 6 8 Calculations 12 - 6 = 6 14 – 6 = 8

Protons, neutrons, and electrons are made up of even smaller particles called quarks and leptons.

History of the Atom

Person Where he was from and What they did when Democritus Ancient Greece Named the Atom John Dalton England 1803 Proposed an “atomic theory” of solid atoms based on mass J.J. Thomson England 1897 Discovered the electron Ernest Rutherford England 1914 Discovered the proton using his famous gold foil experiment James Chadwick England 1932 Discovered the Neutron Neils Bohr Denmark 1922 Proposed that electrons orbited the nucleus like planets orbit the sun

Dalton’s Theory 1. All elements made up of atoms. 2. Atoms of the same element have the same mass. 3. Atoms of different elements have different masses. 4. Atoms combine in small whole number ratios.

He only got 2 of the four right. 1 and 4 are correct. 2 and 3 are incorrect. Atoms of the same element can have DIFFERENT masses and are called ISOTOPES. Periodic Table of the Elements - contains 112 known elements - created by Russian chemist Dmitri Mendeleev - listed in order of their Atomic Number (number of protons) - vertical columns called families and have similar chemical properties o families have the same number of electrons in their outer shell - rows are called periods and have the same number of occupied energy levels.

Periodic Law- when elements are put in order of their atomic numbers (number of protons) there is a repetition of similar properties as you move through the chart

Metals - Shiny - good conductors of heat and electricity - malleable (can be hammered into thin sheets) - ductile (can be drawn into wire) - lose electrons in reactions - less than 4 electrons in their outer shell - found on left side of the periodic table

Nonmetals - dull - brittle (break easily) - gain electrons in reactions - have 4 or more electrons in their outer shell - on the right side of the periodic table

Metalloids - have properties of both metals and nonmetals - along the stair step line that separates metals and nonmetals

Alkali Metals - far left side vertical column on the periodic table - soft - silvery white - highly reactive - never found as elements in nature - only have one electron in their outer shell - can react explosively with water

Alkaline Earth Metals - 2 electrons in outer shell - found in minerals in the earth’s crust - not as reactive as Alkali Metals - in second column from the left

Transition Metals - metals in the 10 shorter columns in the middle of the periodic table - usually have 2 outer shell electrons - form brightly colored compounds Rare Earth Metals - Lanthanide series - Actinide series - At bottom of chart - All actinides are radioactive - All elements after uranium are synthetic or man-made

Halogens - second column from the right - 7 outer shell electrons - react with metals to form salts - most reactive nonmetals

Noble Gases - Vertical column on the far right of the periodic table - have full outer shell of electrons - do not react normally

Kinetic Theory - All matter is made of atoms and molecules that act like tiny particles. - These tiny particles are always in motion. The higher the temperature the faster the particles move. - At the same temperature, more massive (heavier) particles move slower than less massive (lighter) particles.

Solids- - rigid structure - do not take the shape of their container - molecules vibrate in their positions but do not move past each other

Liquids - take the shape of their container - molecules can move past each other - can flow - have freedom of movement

Gases - can fill their container - spread in all directions - molecules move very fast and are very far apart

State of Matter Shape Volume Solid Definite Definite Liquid Not definite Definite Gas Not definite Not definite

Viscosity-the attraction between molecules of a liquid, determines how fast or slow something flows

Pressure- force per unit area, or force divided by area Solutions- - homogeneous mixtures - same throughout - made up of two parts

Solute- the substance being dissolved Solvent- the substance doing the dissolving

Solubility- the ability of a substance to dissolve in another substance

Acids and Bases

Acids - Substance that produces Hydrogen ions (H+) in solution - Hydrogen combined with one or more nonmetals - Vinegar, citrus fruits, tomatoes, tea, sodas - Sour taste - Turn blue litmus red - pH less than 7 - can neutralize bases

Bases - substance that produces hydroxide ions in solution (OH -) - metal combined with a hydroxide - slippery - taste bitter - turn red litmus blue (base- blue- bitter- remember your b’s) - pH greater than 7 - neutralize acids Neutralization reactions- reaction between an acid and a base producing a salt and water pH scale – how basic or acidic something is

7 is neutral example: pure water less than 7- acidic hydrochloric acid, sodas greater than 7- basic baking soda, ammonia

Indicators- change color in different pH solutions Indicators tell the pH of a solution Examples: phenolphthalein and litmus

RADIOACTIVITY Nuclear changes- changes in the nucleus of an atom

3 Types of Nuclear Reactions Nuclear Fission Splitting the nucleus into two smaller nuclei Nuclear chain reaction- the splitting of the first nucleus releases particles which strike nearby nuclei, and cause them to split. This continues until there are no more nuclei to split or all the particles are absorbed. The splitting of a nucleus releases a great deal of energy Uncontrolled chain reactions are used in nuclear bombs Controlled nuclear fission is used to create electricity

Nuclear Fusion Two smaller nuclei join together to create a larger nucleus Occurs in stars and the sun

Radioactive Decay Spontaneous breakdown of a nucleus Releases particles or rays and a lot of energy

3 types of decay

Alpha decay Positively charged Release of a helium nucleus from the nucleus undergoing decay (2 protons and 2 neutrons) Easiest radiation to protect yourself from Stopped by a sheet of paper Beta decay Negatively charged particle High speed electrons emitted from nucleus Can be stopped by a thin sheet of aluminum foil Gamma decay High energy radiation No particle emitted just energy Can penetrate several feet of concrete

Half- Life Amount of time it takes for half of a sample to undergo radioactive decay Number of Half lives Amount of sample remaining 1 ½ ½ sample remaining 2 ½ x ½ ¼ sample remaining 1 3 ½ x ½ x ½ /8 sample remaining 1 4 ½ x ½ x ½ x ½ /16 sample remaining

PHYSICAL CONCEPTS

Force - a push or pull on an object - mass times acceleration

Types of Forces Gravitational force- a universal force between two objects, all objects exert gravity, but it may not be measurable Weight- measure of the force of gravity on an object Gravity is dependent on the size of the objects and the distance between them The further apart two objects are the more the gravity between them decreases

Electromagnetic Force- caused by positive and negative electrical charges in matter Electric forces- forces between electric charges Magnetic forces- forces between magnetic charges Opposites attract Like charges repel Nuclear Forces- forces in an atom’s nucleus that hold the protons and neutrons together Frictional Forces- forces that oppose the motion of two objects in contact - sliding friction occurs when a solid surface slides over another solid surface - rolling friction occurs when an object rolls across a solid surface, rolling friction is less than sliding friction - static friction occurs between the surfaces of two objects that touch but do not move

Net force- combination of all the forces on an object

Net force = 20 N + -20N Net force = 0 N

Balanced Forces- net force equal to zero Unbalanced Forces- net force not equal to zero

Unbalanced forces cause an object’s motion to change

Speed- how fast something goes

Average speed = distance divided by time

Velocity= speed AND direction Momentum is how hard something is to stop

Momentum = mass times velocity p = mv (p = momentum)

Acceleration= change in velocity over time A = vf – vi/ t

Unit of force is the Newton (N) Newton's Laws of Motion

Newton's Newton's 3rd law of 1st Law of Newton's motion Motion 2nd Law of Motion

F= ma an object at for every rest will action there stay at rest is an equal and an but object in opposite motion will reaction remain in motion until a force acts upon it

inertia- resistance to change in motion

A man pushes a 50 kg box across a horizontal cement surface, causing the box to accelerate at 0.50 m/s2. If he pushes with a force of 40 N, what is the frictional force acting between the box and the floor?

Net force= mass times acceleration FNET = ma 2 FNET = (50 kg)(0.50m/s )= 25 N Ffriction= Fman –F net = 40 N – 25 N= 15 N Work Work= force times distance W=fd If the force doesn’t act over a distance then no work is done Unit of work is the Joule (J)

Power Rate at which work is done Power = work divided by time P = w/t Unit of power is the Watt (W)

Simple Machines Make work easier or faster Do NOT decrease the amount of work done Work with one movement 6 types Lever Pulley Wheel and axle Inclined plane Screw Wedge Levers 3 Types

1st class lever fulcrum in the middle

2nd class lever load is in the middle 3rd class lever effort is in the middle

Inclined planes- ramps Pulleys- wheels with a rope wrapped around them Screws- an inclined plane wrapped around a cylinder Wheel and axle- a wheel attached to a rod Wedge –two inclined planes back to back

Effort force- the force applied Work input- work done on a machine Effort distance- the distance through which the effort force acts

Wi = Fe x de

Work output – the amount of work the machine does Resistance force – the force applied by the machine Resistance distance – the distance the resistance force moves through

Wo = Fr x dr

Mechanical advantage- the number of times the machine multiplies the effort force

MA= Fr / Fe or MA = de/ dr

Efficiency- a comparison of the work output to the work input, written as a percentage

E=( Wo / Wi ) x 100%

Efficiency can never be more than 100%

ENERGY

Law of Conservation of Energy Energy can never be created nor destroyed, it only changes forms.

Types of energy Light (Radiant) Electromagnetic Sound Heat (Thermal) Electrical Nuclear Chemical Mechanical

Mechanical energy- the energy of objects 2 types of mechanical energy Kinetic energy- energy of motion KE= ½ mv2 m = mass v = velocity Gravitational Potential energy- energy of position PE = mgh m = mass g = gravity = 9.8 m/s2 h = height above ground Energy Sources Fossil Fuels ( need to reduce dependence) Geothermal (heat from inside the earth) Hydroelectric (using running water to make electricity) Nuclear Solar (from the sun) Wind

Heat transfer The movement of thermal energy from warmer to cooler materials 3 ways heat transfer occurs 1. Conduction- heat transferred by two objects in contact with each other a. Conductors- materials that allow heat to transfer easily b. Insulators- materials that slow the transfer of heat 2. Convection- heat transferred by the movement of fluids 3. Radiation- heat transferred through electromagnetic waves, can move through empty space, how the sun’s energy gets to earth

Wave A disturbance that repeats the same cycle of motion Transfers energy Transverse wave particles move at right angles to the direction of the wave (particles move up and down) example: ocean waves Longitudinal waves particles move in the same direction as the direction of energy ( move back and forth)

Waves Crest- highest point of a transverse wave Trough- lowest point of a transverse wave Amplitude- the distance from the line of origin to a crest or trough Proportional to the amount of energy in a wave Wavelength- distance between two consecutive crests or troughs of a wave Symbol lambda (to represent wavelength Frequency- the number of complete waves that pass a point in a certain amount of time Measured in Hertz (Hz) Period- the amount of time it takes for one wave to pass a point Measured in seconds Speed- how fast the wave is moving

Wave speed = frequency times wavelength V = f x 

4 basis wave interactions 1. Reflection- the bouncing back of a wave when it strikes a boundary a. Law of Reflection- the angle at which the wave bounces off a boundary is equal to the angle at which the wave struck the boundary 2. Refraction- The bending of a wave when it passes from one medium to another, this occurs due to a change in speed 3. Diffraction occurs when a wave passes through an opening and spreads out 4. Interference- when two or more waves occupy the same spot and combine to produce a single wave a. Constructive interference- when the waves meet crest to crest or trough to trough and make a larger wave b. Destructive interference when waves meet crest to trough and make a smaller wave c. Total destructive interference- when two waves with the same amplitude meet crest to trough and cancel each other out completely

Electromagnetic Waves All light waves are part of the electromagnetic spectrum. Electromagnetic waves produce both electric fields and magnetic fields. All electromagnetic waves are transverse waves.

All electromagnetic waves travel at the same speed in a vacuum (3.0 x 108 m/s) The full range of frequencies and wavelengths is called the electromagnetic spectrum.

(left to right increasing wavelength, decreasing frequency) Visible light- the part of the electromagnetic spectrum that can be seen by the human eye

Roy G. Biv Red Orange Yellow Green Blue Indigo Violet

Polarized light- light that has been filtered to only vibrate in one direction

Mirrors- Virtual images- appear to be behind the mirror, cannot be shown on a screen Real images- appear in front of the mirror, light rays actually meet there, can be shown on a screen

Plane mirror and convex mirrors form only virtual images Concave mirrors form both real and virtual images.

Concave- mirror that caves in Convex- mirror that bows out

Concave :

Convex: Plane mirror:

Lenses refract light rather than reflect it.

Converging lens:

Diverging lens: Converging (convex lenses) form real and virtual images. Diverging (concave lenses) form virtual images.

Lenses are used to magnify objects and correct vision problems.

Sound Form of energy that causes objects to vibrate Longitudinal waves make up sounds

Compression- area where the particles are closer together (same as a crest in a transverse wave) Rarefaction- area of the wave where the particles are farther apart (same as a trough in a transverse wave)

Loudness- the intensity or amount of energy in the wave Pitch- the frequency of the wave (determines how high or low a wave sounds) Greater the frequency the higher the pitch Lower the frequency the lower the pitch Doppler Effect occurs when a sound source moves, causing the pitch to increase as the source moves closer, and causing the pitch to decrease when the source moves away (remember how an ambulance sounds when it is moving toward you and away from you) Timbre- sound quality, caused by the blending of various pitches or tones Sound that is pleasing to the ear is called music Sound that is not pleasing to the ear is called noise

Sound travels fastest through solids, next fastest through liquids, and slowest through gases. Sound doesn’t travel at all through the vacuum of space (where there is no medium or material to carry it, not to be confused with a vacuum cleaner… sound travels quite well in a vacuum cleaner just ask any indoor pet.)

When sound waves hit another object, they can be absorbed, travel through the object, or they can be reflected.

Reflected sound waves are called echoes.

Electricity

Static electricity- the accumulation of like charges Cause by Friction Rubbing two objects together, like a balloon and your hair Conduction Transfer of charges from one object to another by touching the objects together

Induction A charged object is brought near to an uncharged object, since opposite charges attract, the charges in the uncharged object move in such a way as that the charges opposite the ones on the charged object are closer to the charged object This causes the uncharged object to behave as if it is charged

Law of Electric Charges – opposites attract, like charges repel Electric fields- area in which the electric force is noticeable Strength of electric field depends on the distance from the charged particle Electric discharge- when electric charges leave an object that has static electricity built up

Electric current- the flow of electric charges Electric current is produced by the flow of electrons Electric current only flows in circuits

Circuit- a complete, closed path for electron flow 5 ways to produce an electric current 1. Electromagnetic generators- turn a coil of wire through a magnetic field ( Electromagnetic Induction), as the coil rotates, the flow constantly reverses directions creating an alternating current (AC), this is how electricity is produced for our homes 2. Electrochemical cells- also called batteries, produce electric current from chemical reactions, produces direct current (DC) 3. Solar cells- produce electricity from light 4. Thermocouples- produce electricity from heat 5. piezoelectric cells produce electricity when pressure is applied to certain crystals

Electric Current- when electrons flow through a wire, measured in amperes (A). Potential Difference- the electrical potential energy between two places in a circuit, measured in Volts (V) also called Voltage Resistance- The opposition to the flow of current measured in ohms (). Good conductors such as copper have low resistance Resistance in wires is depends on thickness, length, and temperature

Ohm’s Law V=IR Voltage= current times resistance

Series circuit- charges only have one path to flow through If one light goes out they all go out Rtotal = R1+ R2 + R3….

Parallel Circuit- charges have more than one path to flow through If one light goes out, the others stay on

1 1 1 Rtotal = /R1 + /R2 + /R3…..

Series parallel circuits have some elements in series and some in parallel

Magnetic field- region around a magnet or current carrying wire where magnetic forces are noticeable Magnetism- the force of attraction or repulsion due to electron motion Magnets have 2 poles a north and a south Like poles repel Opposite poles attract Magnetic domains- groups of atoms with magnetic poles aligned If most of the domains line up the material is considered magnetized Electromagnet- a coil of wire wrapped around a iron bar, with electric current flowing through the wire

Generators use electromagnetic induction to create electricity Electromagnetic induction- a wire turning through a magnet to produce electricity