Final Review

inertia

inertia

the tendency of objects in motion to stay in motion and objects at rest to stay at rest unless acted upon by an outside force

kinetic energy

energy being exercised through movement

potential energy

energy that may be exercised in the future, caused by forces acting upon an object

thermal energy

energy released through thermal motion

heat - work

change in external energy =

orbitals

1s 2s 2p 3s 3p 4s 3d 4p 5s 4p 5p 6s 4f 5p 6p …

spontaneity

a reaction may be more likely to go in one direction than the other

entropy

∆S, a measure of disorder, the likelihood of an arrangement of molecules, the amount of information needed to exactly specify the state of a system

enthalpy

∆H, measure of how much energy is taken up or released by a chemical reaction when no work is done

symmetry

an aspect of the system that does not change even when some aspect of the system changes

• if the forces acting on an object are the same, Newtons’s laws do not change if you move an object to a different location, rotate it, move it at a constant velocity, or allow time to pass.

bosons

• gluons (strong)

  • pion: allow to change from proton to neutron, allow p/n to stay together

• w+ w- 2o (weak)

• photons — v with a curl on the left side (EM)

quantitation

important to experiments; proved that air is not an element but composed of multiple materials

second law of thermodynamics

the entropy of the universe always increases, so reactions will always proceed in the direction that increases the entropy of the universe

light

wave argument: 2-slit experiment

particle argument: photoelectric effect experiment

diffraction

present in the 2-slit experiment

a wave spreads out after passing through a slit

silk and glass rod

experiment involving electron transfer changing the charge and attraction of objects

electricity and magnetism

related because moving electric fields create magnetic currents +v/v

electromagnet

created when an electric current is moved around a piece of iron, turning the piece of iron into a magnet

dynamo

created when magnets are moved around a wire, creating an electric current in the wire

electric field

created between objects with an electric charge

strength is proportional directly to electric charge and inversely to the square of the distance between the charged objects

constants

describe field strength, which is determined by wave speed (the speed of light) → Maxwell posits that light is a wave of EM field oscillations

EM field oscillations

changing electric and magnetic fields induce each other and propagate over space at the speed of light; makes up EM radiation

NaCl

experiment led to the discovery of electrons

run an electric current through NaCl → separates Na and Cl

cathode ray tube

experiment enhanced understanding of electrons

shoot electrons through gas → electric and magnetic fields can change electron trajectories → electrons have negative charge, we can determine their mass ratios

special relativity

theory that the speed of light is absolute

• always travels at the same speed in a vacuum

• observers will agree on the speed because measuring instruments are relative

• works for velocities but not accelerations

e = mc2

we see the ramifications of this equation in any reaction in which energy is emitted

mass

increases exponentially as an object approaches the speed of light

force

= mass x acceleration

charge

can be determined by seeing if a particle’s trajectory bends in an electric field

• bends +: negative charge

• bends -: positive charge

solar system model

evidence: gold foil experiments

problem: classical physics couldn’t explain why the protons would stay in the nucleus

black bodies

objects that can emit/absorb any frequency of EM radiation

ultraviolet catastrophe

classical physics predicted that black bodies would emit ever-increasing amounts of light (and thus energy), which is impossible

photoelectric effect

experiment

photons collide with atoms, giving them energy → if the photons have enough energy, electrons are ejected → electrons behave as particles in cathode rays

Heisenberg uncertainty principle

there are certain pairs of parameters for which the more closely the value of one is constrained, the more the other member of the pair is unconstrained (can take on more values)

• eg. amount of energy/time

virtual particles

created from the energy of the vacuum, must be paid back quickly

n

the average distance from nucleus from which the electron is detected

l

the shape of the volume of space where electrons are likely detected

m

an orbital’s orientation in space

psi

wave function, can be manipulated to tell us everything that can be known about a particle

psi squared

the probability of finding an electron in a certain region at a certain time

Schrodinger’s equation

relates psi to the energy of an electron, helps us understand electrons’ wave function

pion

pairs of opposite matter and anti-matter quarks

• eg. red up and anti-red anti-down

stability

determined by the ratio of protons to neutrons

• higher weights need more neutrons

grand unified theory

EM and weak interactions are different parts of the same force, this theory wants to show that strong interactions are part of this force too

Higgs field

a field whose lowest value occurs when the field’s energy is a non-zero value

gravity

general theory of relativity:

• not a force, but geometry

• the curvature of space-time is caused by mass, energy, and pressure

  • these make space curve in on itself and contract

flat geometry

• specific critical density

• parallel lines don’t meet

• triangles are 180°

• universe slowly increases in volume

open geometry

• density is less than the critical value

• parallel lines get further apart

• triangles are less than 180°

• universe rapidly increases in volume

closed geometry

• density is more than the critical value

• parallel lines eventually meet

• triangles are more than 180°

• universe will eventually collapse in a crunch

big bang theory

universe was small and dense, then exploded outward with enormous force

• galaxies around us are red-shifted (moving away)

• further objects are moving away faster

• so, the universe was probably much smaller

cosmic background radiation

EM radiation protons that are present uniformly over space

string theory

all particles are actually made of the same tiny string that vibrates in different ways to exhibit the characteristics of different particles

spontaneity

∆G, whether in a certain set of conditions a reaction will go in a certain direction without giving off a net amount of energy

W

the number of different states in which the system can possibly be without changing the energy

joule

experiment

energy is energy, calories and joules can be converted into each other

lavoisier

experiment

mass cannot be created or destroyed in reactions

• include mass of gas

prism

experiment

light can be focused and diffracted

• colored light → focuses into white light

• white light → diffracts into colors

leydon jar

experiment

lightning used to charge leydon jar

frog legs

experiment

move because of electrodes

gold foil

experiment

bombard foil with alpha particles → most went right through but some were stopped → positive central charge (nucleus) in atoms, but mostly empty space