Exam 2 Flashcards
wave
a traveling disturbance that carries energy from one place to another without requiring matter to travel across the intervening distance
wavelength
the distance between adjacent wave crests, the highest points of adjacent waves
frequency
the number of wave crests that go by a given point every second. a wave completing one cycle has a frequency of one hertz.
hertz (Hz)
the unit of measurement for the frequency of waves; one wave cycle per second
interference
when waves from two diff sources come together at a single point, they interfere with each other.
electromagnetic wave/ radiation
a form of radiant energy that reacts with matter by being transmitted, absorbed, or scattered. A self-propagating wave made up of electric and magnetic fields fluctuating together. A wave created when electrical charges accelerate, but requiring no medium for transfer.
light
a form of EM wave to which the human eye is sensitive. Light travels at a constant speed (c) and it needs no medium to travel.
speed of light (c)
the velocity at which all EM waves travel, regardless of their wavelength or frequency; equal to 300 million m/sec
Doppler Effect
the change in frequency of wavelength of a wave detected by an observer bc the source of the wave is moving
transmission
one of three responses of an EM wave encountering matter, in which light energy passes through the matter unaffected (light transmits through glass)
refraction
a response of an EM wave to matter, in which the wave slows down and alters direction
absorption
one of three possible responses of an EM wave encountering matter, in which light energy is converted into some other form, usually heat energy
diffuse scattering
a process by which light waves are absorbed and reemitted in all directions by a medium such as clouds or snow
Electromagnetic spectrum
the entire array of waves, varying in frequency and wavelength, but all resulting from an accelerating electrical charge; includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays, and others
radio waves
part of the EM spectrum that ranges from the longest waves–wavelengths linger that Earth’s diameter–to waves a few meters long
microwaves
EM waves, with wavelengths ranging from apprx. 1 meter to 1 millimeter, which are used extensively for line-of-sight communications and cooking
infrared radiation
wavelengths of electromagnetic radiation that extend from a millimeter to a micron; felt as heat radiation
visible light
EM waves with a wavelength that can be interpreted by nerve receptors in the brain and seen as color; wavelengths range from 700 nanometers for red light to 400 nanometers for violet light
X-ray
high-frequency and high-energy EM waves that range in wavelength from 100 nanometers to 0.1 nanometer, used in medicine and industry
Gamma ray
the highest energy wave of the EM spectrum with wavelengths less than the size of an atom, less than one-trillionth of a meter; normally emitted in very high-energy nuclear particle reactions
frames of reference
the physical surroundings from which a person observes and measures the world
theory of relativity
the idea that the laws of nature are the same in all frames of reference. Einstein divided his theory into 2 parts- special and general relativity
special relativity
refers to things moving at a constant speed; deals with reference frames that do not accelerate
general relativity
refers to anything moving regardless of velocity
time dilation
a phenomenon in special relativity in which moving clocks appear to tick more slowly than stationary ones
length contraction
phenomenon in relativity in which moving objects appear to be shorter than stationary ones in the direction of motion
element
material made from a single type of atom, which cannot be broken down chemically any further
atom
fundamental building block for all matter; smallest representative sample of an element . consists of a positively-charged nucleus surrounded by negatively-charged electrons
molecule
a cluster of atoms that bond together; the basic constituent of many diff kinds of material
periodic table of elements
organizational system for elements created by Mendeleev in 1869; organized by atomic weights (rows) and chemical prop (columns); elements place on the table reflects the arrangement of electrons in their orbit
electron
tiny, negatively-charged particles that surround a positively-charged nucleus of an atom
Nucleus
1) very small, compact object at the center of an atom; made up of protons and neutrons. 2) powerhouse of a cell
Bohr Atom
a model of the atom, developed by Niehl’s Bohr in 1913, in which electrons exist only in allowed energy levels which maintain fixed energy for long periods of time, w/o giving off radiation
photon
particle-like unit of light, emitted or absorbed by an atom when an electrically-charged electron changes state. the form of a single packet of EM radiation
Quantum leap/ jump
Niehls Bohr-process by which an electron changes it’s energy state w/o ever possessing an energy intermediate between the original and the final energy state
spectrum
the characteristic signal from the total collection of photons emitted by a given atom that can be used to identify the chemical elements in a material; the atomic fingerprint
spectroscopy
the study of the emission and absorption spectra of materials in order to discover the chemical makeup of a material; a standard tool used in almost every branch of science
when can science answer a question
it can, if you can falsify it
dalton
theorized atoms were like cannon balls
thompson
made cathode ray tube (CRT) and came up with the raisin pudding model
rutherford
solar system model; atom is almost nothing at all
atomic number
number of protons in an atom
atomic mass
protons + neutrons
isotope
same elements with diff atomic masses
atomic weight
how much a mole of it actually weighs- average of isotopes and atomic masses
wave particle duality
electrons act as waves and particles
strong nuclear force
keeps protons together inside nucleus
nuclear fission
what powers the sun
quantum mechanics
the branch of science that is devoted to the study of the motion of objects that come in small bundles, or quanta, which applies to the subatomic world
uncertainty principle
the idea quantified by Heisenberg in 1927, that a quantum scale, the location and velocity of an object can be never be known at the same time bc quantum-scale measurements affects the object being measured. =the measurement of an objects position, times the error of uncertainty
(Heisenberg) uncertainty principle
the more you know about a particles mass and direction, the less you know about where it’s going; idea quantified by Heisenberg in 1927, that a quantum scale, the location and velocity of an object can be never be known at the same time bc quantum-scale measurements affects the object being measured. =the measurement of an objects position, times the error of uncertainty
probability
the likelihood that an event will occur or that on object will be in one state or another; how nature is described in the subatomic world
Louis de’Broglie
sort of solved Niehl’s Bohr problem with wave particle duality theory
shorter wavelength
higher frequency, more energy
chemical bond
attraction that results from the redistribution of electrons between 2 or more atoms leadings to a more stable configuration- kinds ionic, covalent, and metallic
change of state
transition between solid, liquid, and gas forms
chemical reaction
process by which atoms and molecules come together or fall apart. rearrangement of electrons to form chemical bonds
covalent bond (atomic)
sharing electrons in the outer shells; bond in which neighboring molecules share electrons in a strongly bonded group of at least 2 atoms
hydrogen bond (molecular)
when molecules achieve polarity by the bonds among its atoms; a chemical bond that may form when polarized hydrogen atoms link to other atoms by a covalent or ionic bond
gas
any collection of atoms or molecules that expands to take shape and fill the volume available in it’s container
hydrocarbon
a chain-like molecule from a chemical compound of carbon and hydrogen, which provides the most efficient fuels for combustion with only water and carbon dioxide as products
ionic bond (atomic)
exchange electrons and stick together; a chemical bond in which the electrostatic force between 2 oppositely charged ions hold the atom in place
chemistry happens…
in valence shells
metallic bond (atomic)
every atom shares electrons; in a sea of electrons, sharing them all the time
isomer
cannot be turned into each other, they must be taken apart to rebuild
stereoisomer
optical isomer, mirror image of each other; rotate polarized light in diff directions
alpha carbon
carbon at center of molecule with all diff configurations around it
composite material
a combo of two or more substances in which the strength of one of the constituents is used to offset the weakness of another, resulting in anew material whose strengths are greater than any of its components; ex. plywood or reinforced concrete
electrical conductor
any material capable of carrying an electrical current
electrical resistance
the quantity, measured in ohms, that represents how hard it is to push electrons through a material.
electrical insulator
material that will not conduct electricity
semi-conductor
materials that conduct electricity but do not conduct it very well. neither a good conductor or a good insulator; ex. silicon
superconductivity
the ability of some materials to exhibit the complete absence of any electrical resistance, usually when cooled to within a few degrees of absolute zero
doping
the addition of a minor impurity to a semiconductor
diode
an electronic device that allows electrical current to flow only in one direction
transistor
a device that sandwiches p- and n- type semiconductors in an arrangement that can amplify or redirect an electrical current running through it; a device that played an essential role in the development of modern electronics
microchip
a complex array of p- and n-type semiconductors, which may incorporate hundreds or thousands of transistors in one integrated circuit
bit
binary-digit; a unit of measurement for information equal to “yes-no” or “on-off”
byte
in a computer, a group of eight switches storing eight bits of information; the basic information unit of most modern computers
Rutherford
solar system model
dalton
bowling ball model
thomson
raisin pudding model
niehls bohr
quantum leap/allowed orbits theory
de broglie
wave particle duality- electrons act as both
longitudinal wave
moves in the same direction of medium i.e. sound
transverse
moves perpendicular to medium i.e. water
ion
atom with unbalanced number of protons and electrons
isotope
atoms whose nuclei have the same number of protons but a different number of neutrons
atomic number
number of protons in an element
atomic mass
how many protons and neutrons are in a given atom
atomic weight
average of all atomic masses for that element
how many electrons are in 31P++
subtract atomic number from mass to get neutrons
subtract however many pluses from protons to get electrons- in this case it would be 13 bc 15-2=13
