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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