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Ch.4

Terms in this set (85)

Democritus (____ BC)'s theory
400, Theorized all matter is made up of individual undividable particles called atoms.
Democritus had no ____________ ____________
Experimental evidence
John Dalton (_____ AC)'s theory
1804, Theorized all matter is made up of individual undividable particles called atoms
John Dalton had ____________ ____________
Experimental evidence
John Dalton's evidence
Ratio of masses of the elements in a compound is always the same
John Dalton's model
Solid sphere model
JJ Thomson (_____ AC)'s experiment
Cathode ray tube experiment
Cathode ray tube experiment results
Beam of charged particles were attracted to positive plate and repelled away from negative plate
Subatomic
Inside atom
Cathode ray tube experiment was evidence for
Subatomic negative particles
Subatomic negative particles
Electrons
JJ Thomson's model
Plum pudding model
Ernest Rutherford (_____ AC)'s experiment
Gold foil experiment to test plum pudding model
Ernest Rutherford's results
Some particles were deflected
Rutherford's experiment proved that
Atom is mostly empty space
Ernest Rutherford's model
New atomic model
New atomic model
Small, dense, positive nucleus, surrounded by negative charged electron
Neils Bohr (_____ AD)'s theory
Theorized that electrons move in definite orbits around the nucleus
_______ _______ talks about energy levels and orbitals
Neils Bohr
Energy levels
Specific energies an electron can have
Orbitals
Specific regions where electron are located
Neil Bohr's evidence
Emission spectrums
Example of emission spectrums
Fireworks
Atomos
Uncut or indivisible
Democritus believed that all matter consisted of extremely ______ particles that cannot be _________. He called these particles _______
Small, divided, atoms
Dalton gathered evidence for the existence of ______ by measuring the _______ of elements that combine when ___________ form. no matter how ______ or ______ the sample was, the ______ of the ________ of the elements was always the same.
Atoms, masses, compounds, large, small, ratio, masses
________ did not believe that there was a _______ to the number of times matter could be ________
Aristotle, limit, divided
Dalton proposed the theory that all _______ is made up of __________ particles called _______, which cannot be ________
Matter, individual, atoms, divided
Dalton's theory:
-All elements are composed of ______
-All atoms of the same _________ have the same _____, and atoms of different _________ have different ______
-_________ contain atoms of more than 1 _________
-In a particular compound, atoms of __________ elements always __________ in the ______ way
Atoms, element, mass, elements, masses, compounds, element, different, combine, same
______, _______, and ______ are ________ particles
Protons, electrons, neutrons, subatomic
Rutherford had seen evidence for the existence of __ ________ particle(s) and predicted the existence of a ____ one
2 subatomic, third
Each nucleus must contain at least __ particle(s) with a ______ charge
1, positive
Proton
Positively charged subatomic particle that is found in the nucleus of an atom
1+ (charge)
Proton
Electron comes from a Greek word meaning _____
Amber
Electron
Negatively charged subatomic particle that is found in the space outside the nucleus
1- (charge)
Electron
In 1932, ____ ______ designed an experiment to show that ______ exist. He concluded that the particles he produced were ______ because a ______ object did not deflect their paths
James Chadwick, neutrons, neutral, charged
Neutron
Neutral subatomic particle that is found in the nucleus of an atom
_______ particles can be distinguished by ___, ____, and ______ in an atom
Subatomic, mass, charge, location
Protons have a mass of __, neutrons have a mass of __, and electrons have a mass of __/____
1, 1, 1, 1836
0 (charge)
Neutron
Everything scientists know about subatomic particles is based on how they ______, scientists still do not have an instrument that can show the ______ of an _____
Behave, inside, atom
Atomic number
Number of protons in an atom
Atoms of ________ elements have different _____ numbers
Different, atomic
Mass number
Sum of protons and neutrons in the nucleus of an atom
Isotopes
Atoms of the same element that have different numbers of neutrons and different mass numbers
Isotopes of an element have the same _____ _______ and different ____ numbers because they have different numbers of ______
Atomic numbers, mass, neutrons
Energy levels
The possible energies that electrons in an atom can have
Each ______ in an atom has a ______ amount of energy. If an atom ____ or ____ energy, the ____ of an ______ can change
Electron, specific, gains, loses, energy, electron
An electron ? exist ______ energy levels
Cannot, between
Scientist can measure the energy _____ or ______ when an electron changes _____ ______
Gained, released, energy levels
When fireworks explode, ____ produced by the explosion cause some electrons to move to _____ energy levels. When they move back to _____ energy levels, they emit ____ and some of that ____ is released as ____
Heat, higher, lower, energy, energy, light
Bohr was correct in assigning ____ _____ to electrons but was incorrect in assuming that electrons moved like ______ in a ______ ______
Energy levels, planets, solar system
Electron cloud
Visual model of the most likely locations for electrons in an atom
Modern scientists use the _______ _____ model to describe the _______ locations of ______ around the ______
Electron cloud, possible, electrons, nucleus
Orbital
Region of space around the nucleus where an electron is likely to be found
An electron cloud is a good ___________ of how electrons _____ in their ______
Approximation, behave, orbitals
1st energy level has __ orbital(s) and a max of __ electron(s)
1, 2
2nd energy level has __ orbitals and a max of __ electrons
4, 8
3rd energy level has __ orbitals and a max of __ electrons
9, 18
4th energy level has __ orbitals and a max of __ electron
16, 32
Each orbital can contain __ electrons at most
2
Electron configuration
The arrangement of electrons in the orbitals of an atom
The most stable electron __________ is the one in which the electrons are in _______ with the ______ possible energies
Configuration, orbitals, lowest
Ground state
When all the electrons in an atom have the lowest possible energies
Excited state
When an atom has enough energy to move some electrons to an orbital with a higher energy
An _____ state is less stable than a _____ state
Excited, ground
Helium, neon, argon, krypton, and xenon atoms returning from _____ states to _____ states emit the ____ you see in ____ ____
Excited, ground, light, neon lights
Thomson concluded that the particles in the ____ had a ________ charge because they were attracted to the ________ plate
Beam, negative, positive
_______'s evidence provided the ____ evidence that ____ are made of even ______ particles
Thomson, first, atoms, smaller
Plum pudding model is also known as the
Chocolate chip ice cream model
Nucleus
Dense, positively charged mass located in the center of the atom
According to ________'s model, all of an atom's _______ charge is concentrated in its ______
Rutherford, positive, nucleus
__________ has the greatest atomic radius
Francium
Thomson's device
Sealed glass tube from which most of the air has been removed. There is a metal disk at each end of the tube. Wires connect the disk to an electric current. when the current is turned on, one disk becomes negatively charged and one becomes positively charged. A glowing beam appears in the center.
Thomson hypothesized that he beam was a stream of __________ particles that interacted with the ____ in the tube and cause it to ______
Charged, air, glow
To test his hypothesis, Thomson placed a pair of _________ metal plates on either side of the glass tube. The plates caused the beam to ________ from its ________ path. Thomson observed that them was attracted to the _________ plate and away from the _________ plate. He concluded that the beam was made of ____________ charged particles
Charged, deflect, straight, positive, negative, negatively
Alpha particles
Fast-moving positively charged particles
________ emits fast moving positively charged particles called _____ particles
Uranium, alpha
Gold Foil Experiment
Marsden aimed a narrow beam of alpha particles at the gold. The screen around the gold was made of a material that produced a flash of light when struck by a fast-moving alpha particle. By observing the flash, Marsden could figure out the path of the particles. Many particles deflected back and some even bounced straight back.
Gold Foil experiment was conducted by _______ ___________
Ernest Marsden
_____________ predicted that the _____ and ________ at any location in the gold would be too ______ to change the path of any particle
Rutherford, mass, charge, small
The alpha particles must have come close to another _________ object. The closer they came, the _________ the deflection was. Many passed through the ______ without being __________ which proved that most of the atom is _______ _______
charged, greater, gold, deflected, empty space
The particles that were deflected by more than ___ degrees came very close to the _________ and the particles that were ___________ were far from the _________
90, nucleus, unaffected, nucleus
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