Physical Science Final Review PDF

Preview

Summary

Everything you need to know for the Final for Physical Science. Study guide given by the professor. All classes take the same final....

Description

Six self-evident truths 1. Existence: the fact or state of having actual or real being 2. Causality: cause must precede effect 3. Position-symmetry: laws of nature are the same everywhere in the universe 4. Principle of noncontradiction: of two contradictory propositions, both cannot be true 5. Time symmetry: laws of nature have/will remain the same over time 6. Occam's razor: the simplest explanation is most likely to be correct Sources of Knowledge - AIRS - Authority - accepted source of expert information or advice - Intuition - knowing or sensing without use of rational processes (immediate cognition) - Reason - capacity for logical, rational, and analytic thought - intelligence - Sensory Data - knowledge obtained through the senses Four fundamental forces (strongest to weakest) 1. 2. 3. 4.

Strong nuclear - holds nucleus of atom together (protons and neutrons)(Short range) Electromagnetic - interaction between charged particles (Holds molecules together) Weak nuclear - interactions between nuclei (not important. Never an answer on the test) Gravity - the interactions between anything with mass (longest range)

Newton's laws of motion - First law - object at rest will stay at rest and an object in motion will stay in motion unless acted upon by an unbalanced force (inertia). TA Ex: Whiplash in car ride. - Second law - Force = mass x acceleration. Anytime there is acceleration there is a force acting on it. Applies to things in orbit. Remember if you are changing direction or speed (up or down) you are accelerating! Acceleration is always in the same direction as the net force. - Third law - for every action, there is an equal and opposite reaction - all forces result from interactions between pairs of objects, each exerting an equal and opposite force. Although the masses and changes in velocity of each object may be different. (Remember Train vs Fly example) Forces and Acceleration ● Acceleration - any change in speed or direction ● F = ma ○ If there is an acceleration, there must be a net force and vice versa ○ if you are slowing down, your velocity and acceleration are in different directions. If you are speeding up your velocity and acceleration are in the same direction ● Uniform motion - object is at rest or is moving at a constant speed in a straight line. All forces are balanced ○ When in uniform motion in a vehicle with no windows, there's n  o test you can do to prove whether you are in motion or at rest.

○ ○ ○

Elevator example - contact force vs. gravity If net force is down, acceleration is also down https://www.youtube.com/watch?v=rZo8-ihCA9E

Newton's laws and collisions ●

Third law states that forces occur in equal and opposite pairs ○ Ex: I push on the chair just as much as the chair pushes on me ○ see “moose and log” example in book pg 56

●

Imagine a collision between a semi truck and fly (they exert the same force on each other, but fly experiences the greater acceleration) ○ Compare the forces between the two (third law) - the forces are the same ○ Compare accelerations between the two (F = ma) - the acceleration of the fly is greater because it has a smaller mass. The truck deccelerates too, but it isn’t enough to notice. ○ Small mass = large acceleration ○ large mass = small acceleration

Gravity ● All objects experience the same acceleration due to gravity in the absence of air friction (ignore air friction in all cases on the test) ● Universal law of Gravity = GmM / d^2 ○ The force of gravity depends on the mass of the 2 objects, and how far apart they are ■ two objects close together experience more gravitational force than two objects further apart that have the same mass ■ an object with a small mass and an object with 2x that mass and are same distance apart, have more gravitational force than 2 objects of the same size at an equal distance ■ bigger and closer = stronger force ○ ex: A bobcat and a squirrel are dropped from an equal height, on which is there greater gravitational force? ■ answer: The bobcat! (in my experience bobcats have more mass) i second that ○ Heavier objects experience greater gravitational force because it takes more to move them, but the same acceleration because Gravity is constant ○ A squirrel and a bobcat are dropped from an equal height, which has the greater acceleration? ■ answer: They are the same because gravity is constant ○ Force is proportional to mass ○ inverse proportional to distance (one increases, the other decreases) Electric force law ● Force = kQq / d^2

○

○ ○

The force between two charges depends on the size of the charge and the distance between them ■ Things that are closer together have more force ■ Things that have a larger charge have more force The sign of the charge does not matter for the force (SIZE MATTERS) < Like charges repel each other, opposite charges attract

Electrical Potential energy ● Energy associated with the relative position of charged objects ● For like charges, they have the most potential energy when they are close together (they have the most to separate) ● For opposite charges, they have the most potential energy when they are far apart (they have the potential to come together) ○ SIGN matters ● Ex: does an electron have more electrical potential energy when it is close to the nucleus or far away from the nucleus? ○ far away because it is - and the nucleus is +

Forces in fluids ● Pressure in a fluid increases with depth ● Buoyant force - the  buoyant force is equal to the weight of the displaced fluid (volume of object and density of fluid) (buoyant force caused by pressure) ○ Therefore, buoyant force depends on the volume of the object and the density of fluid ○ When determining if something will float or sink, you need to account for the buoyant force ○ For an object floating on the surface, the buoyant force and the gravitational are balanced. Beach ball example ○ When something sinks, it means the gravitational force is greater than the buoyant force ● Buoyant force is caused by greater pressure at greater depth, so when an object is submerged the bottom of an object will experience a greater pressure than the top and there will be a net force upwards (not important for test) ● BUT the size of the buoyant force is ONLY dependent on the volume of an object, If object A and object B have the same volume they will have the same buoyant force when both are completely submerged, even if object A is at a different depth than object B Special theory of relativity ● The speed of light in a vacuum is constant for all observers in  all reference frames, regardless of the speed of the device emitting the light or the speed of the observer ● If there is a car that is traveling half the speed of light and it turns its headlights on, How fast is the light moving? ○ So nothing can go faster than the speed of light

●

■ The speed of light, not 1.5x the speed of light. As you approach the speed of light, three things happen (short,  fat, and slow/me  after a trip to chipotle :) ) ○ Length contracts in the direction of motion ○ Mass increases (energy is transferred into mass) ○ Time slows down

Conservation laws ● Conserved means to say that it is the same at the beginning and the end ● Things that are conserved ○ Mass (except in relativistic situations) ■ In Nuclear and relativistic situations mass and energy are conserved together, so I can convert mass into energy and visa versa without the universe getting mad ○ Fundamental particles: atomic mass number is always conserved ○ Charge: electrons just transfer from one object to another, they are never destroyed ○ Linear momentum ■ Momentum = mass x velocity ■ Explosion (bomb) example ○ Angular momentum ■ Angular momentum = mass x velocity x radius ■ Ice skater example ● Conservation of energy ○ Energy is neither created nor destroyed, it is just converted from one form to another ○ The process by which energy is converted from one form to another is work

Heat transfer processes ● Conduction - transfer of heat between two objects that are placed in direct contact ○ Putting your hand on a hot stove (DON’T try this at home) ● Convection - hot material moves and transfers heat to colder material ○ Heat from the stove rises and you feel it when you put your hand above the stove (Try this at home!) ● Radiation - transfer of energy from one place to another without any need for intervening matter ○ You feel heat from the stove even when you put your hand to the side of it (you may also try this at home)

Energy ● Kinetic energy - energy of motion ○ KE = 1/2Mass x velocity (need to know it depends on mass and velocity) ● Gravitational potential energy = increases with height and weight

PE = mgh (mass x acceleration of gravity x height) which would you rather drop on your foot, a bowling ball from an inch or a bowling ball from 3 feet? Electrical potential energy - energy associated with the relative position of charged objects Thermal energy (most disordered-most systems end with this) Chemical potential energy (bonds) Elastic potential energy (stretch/compress, rubber bands) Nuclear potential energy (nucleus) ○ Tsar bomb ○ ○

● ● ● ● ●

Unit 2 Types of Waves ● Shear waves/transverse - move perpendicular to the direction they are traveling. Only travel through solids (look like traditional waves, like in diagram)(S waves) Compression waves/Electromagnetic interactions ● Atoms are made of protons, neutrons, and electrons ● strong nuclear force holds nuclei together, electromagnetic force is what pushes them apart’ ● In a transfer of charge, only electrons move ○ Electrons are added to an object to make it negatively charged ○ Electrons are taken from an object to make it positively charged ● longitudinal - move parallel to the direction of the wave (looks like straight line traveling in direction pushed, ie slinky, ex: sound is a compression wave)(P waves) ● Surface waves (don’t really need to know) - this is the type that we feel in an earthquake ● Know the parts of waves (amplitude, wavelength, etc.) ● http://www.acs.psu.edu/drussell/Demos/waves/wavemotion.html Frequency x Wavelength = Speed

Properties of waves ● Reflection - wave bounces off a surface/ ● Refraction - speed of wave changes as it enters a new medium (p waves slow down as they enter liquid outer core) also changes direction (ie stick appearing bent in water)

● ● ● ● Light ● ●

Diffraction - wave spreads out after going through small opening or around corner Interference - when waves overlap, causes constructive and destructive interference (like the slit experiment from Dr. Quantum) Doppler effect - high frequency coming toward you (waves getting to you faster because they are being compressed), low frequency going away (waves need to be longer to get to you) Energy is dependent on Amplitude, think tsunami has lots of energy b/c it’s really tall

Speed of light is constant ALWAYS!!! Particle/Wave duality ○ With mechanical waves, energy depends on amplitude; ○ With light, energy depends on frequency ○ Leading us to the conclusion that light acts as both a wave and particle ○ THE PHOTOELECTRIC EFFECT PROVES THE PARTICLE NATURE OF LIGHT

States of Matter ● Solid, Liquid, Gas, (plasma - don’t need to know) ● Know each of ○ Densities ■ usually solid > liquid > gas > plasma ■ exception is water where solid < liquid ○ How they respond to forces ○ How well they conduct electricity (this usually depends on the kind of matter not its state) ● Understand this graph

Models (know what they look like and which experiments led to them) see summary we did in lab (worksheet 8 I think)

● ●

●

●

●

●

Continuous: what you see is what you get. matter is infinitely divisible ○ Brownian motion - discovery of random movement of particles led to Molecular model (Dalton) ○ Explains states of matter, forces and density ○ but doesn't explain color or electricity ○ Gas discharged tubes and experiments (explained that atoms are made of + and - bits) led to Plum Pudding model (JJ Thompson): Similar to a chocolate chip cookie. dough is + with particles embedded (represented by chocolate chips). + not dense, spread out. - uniform, same size and charge ○ Gold foil experiment (Rutherford) proved that there was very concentrated mass and + charge in nucleus, only a really concentrated + charge (not mass) could have repelled the + alpha particles led to Solar System model: there is a dense positive nucleus with electrons in any orbital around [Jimmy Neutron drawing] ○ Still doesn't explain c olor or accelerating electrons (which would be emitting light at all times) ○ Bohr came along with discrete spectra (electrons emits different colors on different energy levels & electrons exist at specific orbits) led to Bohr model: discrete energy levels. Problem--only works for Hydrogen ○ Orbits would eventually circle into the center and it would collapse on itself ■ We would all glow very brightly and then implode and die, but we’re not dead soo... ○ Double slit experiment: wave particle duality (Watch youtube video: "Dr. Quantum and the Double Slit") led to Quantum Model ○ Electrons behave more like waves, moving between energy levels ○ Electrons are in standing waves of probability ■ Caleb thinks of this as the electron is either at one point somewhere in the orbital or the electron IS the orbital and is kind of crushed and just smeared around it

○

○

Bigger objects (objects with more momentum) don't have much of a wavelength ■ Wavelength of a particle (or anything) is w = h / p (h is a small constant, p is momentum; as p increases, wavelength decreases) You can either know the momentum or the position of an electron, but not both

Electron orbitals (know shapes of s and p orbitals, don’t worry about d and f b/c they’re crazy,)  and understand how to draw and recognize correct energy well diagrams)

● ● ●

S orbital (2 electrons) symmetrical sphere, completely encompasses the Nucleus P orbital (6 electrons) x,y,z--2 electrons in each orbital. 3 orbitals. Orbital diagrams (1s, 2s, 2p, etc.)

Periodic table Atomic volume - as you go towards the right and up the periodic table, atomic volume gets smaller (He is the smallest) Ionization energy (how much energy it takes to remove an electron from an atom) - as you go towards the left and down the periodic table, ionization energy goes down (gets easier to take one off. like losing a child because there’s so many to watch and the one is on the outside) Electronegativity (how greedy an atom is for electrons) follows the same trend as ionization energy Periodic properties - elements in the same column (group) have very similar properties (F, Cl, and I all kill bacteria, because of their tendency to remove electrons from other elements etc.)

Unit 3 Forms of matter Chemical matter ● Pure substances ○ Elements ○ Compounds: specific ratio ● Mixtures ○ Alloys: solid solution of metals ○ Solutions: mixture containing two or more compounds (at least one is a qqqqquliquid) ○ Blend/composites (don’t worry about this) Molecular Matter ● matter made from molecules ● Water is not a network bonding substance Network solids ● matter made from ionic or covalent bonds ● usually form cubic structures Spectrometry vs. Spectroscopy ● Mass spectrometry - break apart a molecule, measure weight of the pieces ○ Largest (farthest right) big spike will be the weight of the original molecule ○ Know how to measure atomic weight ○ ex:

blue: oxygen, black: carbon question: is 44 the atomic weight? How to measure atomic weight? - The atomic weight is the number at the bottom. Carbon = 12, Oxygen = 16 (times 2 b/c there are two of them) 12+16+16 = 44. 44 is the atomic weight of Carbon dioxide

Infrared (IR) spectroscopy ● This is a measure of what amounts of certain wavelengths of light that a molecule absorbs ● Take the absorption spectra and turn it on its side (large spike means that certain color is being absorbed) ○ Elements in the same family have similar absorption patterns

Energy● Activation energy - energy required to start a reaction ● Catalyst - lowers activation energy without changing the reaction ● Enzyme - catalyst in a biological reaction Energetically Favorable vs unfavorable ● Energetically favorable - reaction releases energy (releases heat) - exothermic ● Energetically unfavorable - reaction absorbs energy (absorbs heat) - endothermic Equilibrium - when something is being put together at the same rate it's falling apart Properties of Bond (know this…. like a lot) Web diagram L INK (properties are highlighted in yellow) Metallic bonds ● Characteristics ○ Opaque - can't see through it (light is either absorbed or reflected back) ■ metals have lots of closely spaced energy levels

this means no matter what frequency of light hits a metal there will always be an energy level at the right spot so that an electron can absorb the light ■ Smaller band gaps allow electrons to jump with smaller frequencies of light ■ BEWARE the common misconception of “the energy levels are so close together the light can’t get through” that is just plain wrong Conductive ■ In order for anything to conduct, electrons have to be able to flow ■ Electrons in metals are free-flowing so they can send electrons any direction ■ Band gap ■ In order for electrons to flow they have to be in the conduction band ■ In metals, the conduction band and valence band overlap so electron flow happens naturally ■ In order to decrease band gap in semiconductors, heat them up (add energy) ○ semiconductors - resistance to flow decreases with heat ○ conductors - resistance to flow increases with heat ■ LED ■ Electrons jump between bands and release a photon. They jump to a lower state and release energy in the form of a photon. The bigger the jump, the higher frequency of the photon High melting/boiling points ■ Electrostatic interaction in metallic bonds is very strong - you have to give it a large amount of energy to break such strong bonds ■ The sea of electrons holds the nuclei together Malleable ■ It bends, doesn't break ■ Electrons move around when the physical shape of the metal is changed so that the + nuclei don’t repel each other ■ Delocalized electrons- sea of electrons Electron status KEEP IN MIND ■ With semi-conductors, heat increases conductivity ■ With regular metals, heat decreases conductivity ■ All of the characteristics discussed go back to the fact that electrons are delocalized. There is a 'sea of electrons' ■

○

○

○

○ ○

Ionic bonds - metal and nonmetal (nonmetal steals valence electrons from the metal) ● Characteristics ○ High melting/boiling point ■ Ionic bonds are very strong

○

○

○ ○

■ Electrostatic interactions go in all directions leading to high melting points Transparent ■ Electrons are localized and not moving around ■ energy levels are widely spaced so it takes a lot of energy for an electron to jump from one to another ■ visible light doesn’t have enough energy to allow the electron to jump to the next highest energy level so the electron can’t absorb the light. ● band gap is too large ■ Visible light passes right through Brittle ■ The electrons are localized so they cannot move when the physical structure is altered, like charges repel and material shatters Only conductive in water ■ Ions separate in water so charges can move = conduction! Very salty

Covalent bonds - two nonmetals together (both elements share electrons) ● Low melting point--due to the weak intermolecular forces ● Referred to as molecules ● Transparent ● Don’t conduct electricity Balancing equations ● All atoms want either a full valence shell or empty valence shell ● Elements left of the staircase gives up electrons, right of the staircase steals electrons ● The number of valence electrons that an atom can give...