science ch 9
John Dolton's Atomic Theory (4)
-all matter is made of atoms that cannot be divided/created/destroyed -during a chemical reaction, atoms of one element cannot be converted into atoms of another element -atoms of one element are identical to each other but different from atoms of another element -atoms combine in specific ratios
nuclear can decay 3 types of radiation
-alpha particles -beta particles -gamma rays
democritus' atomic theory (4)
-atoms are small solid objects that cannot be divided/created/destroyed -atoms are constantly moving in empty space -different types of matter are made of different types of atoms -the properties of the atoms determine the properties of matter
what does rutherford's model contain? (2)
-small, dense, positive nucleus -tiny negative charged electrons that surround the nucleus
protons are made up of two ____ quarks and one ____ down quarks
-up -down
Six types of quarks
-up -down -charm -strange -top -bottom
an alpha particle is made of _____ protons and ___ neutrons.
2, 2
who came up with the idea of circular pass for electrons
Bohr
who came up with the idea tha atoms combine in specific ratios?
Dalton
_______ believed that matter is made if small, solid objects called atomos, from which the English word 'atom' is derived
Democritus
________ set up experiments to test Thomson's atomic model and to learn more about what atoms contain
Ernest Rutherford
________ concluded that cathode rays were made of small, negatively charged particles which he called electrons
J.J. Thomson
who discovered the neutron?
James Chadwick
Unsatable atoms are more likely to be _____ than atoms that are stable
Radioactive
Who used the gold foil experiment?
Rutherford
Rutherford's student performed an experiment during which they shot ________________________ particles into a piece of ______________________ foil
alpha, gold
_______ did not believe that empty space exists, but instead believed that all matter is made of fire, water, air, and earth
aristotle
who believed that all matter is made of air, water, fire and earth
aristotle
An _____ is the smallest unit of matter that still represents that element.
atom
smallest piece of an element that still represents the elemant
atom
the number of protons in an atom of an element is the element's ___________
atomic number
john dalton proposed the ________ theory, which was based on careful observations and ________ of chemical reactions
atomic, measurement
Democritus proposed that matter is made of small, indivisible objects called _______
atoms
John Dolton's Atomic Theory- during a chemical reaction, _______ of one element cannot be converted into atoms of another element
atoms
the average mass of the element's isotopes, weighted according to the abundance of each isotope
average atomic mass
the energy released by radioactive decay can be both harmful and _______ to humans
beneficial
when beta decay occurs, a neutron changes into a proton and a high energy eclectron called a _______
beta particle
______ atomic model proposed that ______ move in circular orbits, or ______ around the nucleus
bohrs, electrons, energy levels
you _____ see atoms with just your eyes or most microscopes
cannot
in rutherford's model what was the alpha particle going through?
cathode ray tube
thomson discovered that the rays in a _____ _____ _____ were attracted to a _______ charged plate, which means that the rays have a _________ charge
cathode ray tube, positively, negative
because gamma rays do not contain particles, the release of gamma rays does not _________ one element into another element
change
niels bohr proposed that electrons move in _______ orbits around the nucleus
circular
the limitations of bohr's model is that electrons do not actually move in _________ orbits
circular
John Dolton's Atomic Theory- atoms _________ in specific ratios
combine
John Dolton's Atomic Theory- all matter is made of atoms that cannot be divided, _______, or destroyed
created
dalton's theory states that atoms cannot be divided, _______, or destroyed
created
the idea of an atom was made by
democritus
who first called the building blocks of matter "atoms"?
democritus
atoms of different elements are _____ sizes, but are all very _____
different, small
electrons symbol
e-
many ancient greek philosophers thought that all matter was made of only four elements- fire, water, air, and ____
earth
Thomson's experiment lead to the discovery of the ________
electron
atomic particle with one negative charge (1-)
electron
area around an atomic nucleus where an electron is most likely to be found
electron cloud
in the modern atomic theory, electrons form an _____________, which is an area around the __________ in which an electron is liikely to be located
electron cloud, atomic nucleus
__________have much less mass than the other two particles in an atom
electrons
an ion can be positively or negatively charged depending on whether it has lost or gained ______
electrons
for an atom to be neutral the number of neutrons must = the number of ______
electrons
in bohr's model of the atom, electrons move in _____ orbits around the atom
electrons
in the modern atomic model, _____ form an electron cloud
electrons
of the 3 main subatomic particles, which one has least mass
electrons
in a neutral atom, the number of ______ equals the number of protons because the number of _________ charges must equal the number of positive charges
electrons, negative
when uranium realeases radiation, it changes to a different ________
element
an isotope is often written with the _______ _____ followed by the mass number
element name
an electron cloud is mostly ________ space
empty
negatively charged electrons move in the ______ space surrounding the nucleus
empty
when an electron moves from a higher energy level to a lower energy level, ______ is released- sometimes as visible light
energy
when energy is added to an atom, electrons move to higher ______; when energy is released by the electron, it moves back to a lower level
energy levels
henri becquerel and pierre and marie curie discovered that the radiation released by uranium was made of ______ and ______
energy, particles
when we were studying radioactive, which one did not change it to another element
gamma
what happened because aristotle was so influential?
his ideas were accepted and democritus' ideas were not studied for more than 2,000 years
John Dolton's Atomic Theory- atoms of one element are ______ to each other but _______ from atoms of another element
identical, differerent
according the modern atomic theory, electrons are usually found _______ the nuclues
in the electron cloud
an atom that is no longer neutral because it has gained or lost electrons
ion
atoms of the same element with different number of neutrons are called
isotope
______ are atoms of the same element that have different numbers of _______
isotopes, neutrons
_______ discovered that, in addition to protons, the nucleus also contained neutrons
james chadwick
_______ was one of rutherford's colleagues, he discovered the _______
james chadwick, neutron
________ combined data from his own scientific research with data from the research with data from the research of other scientists to propose a new atomic theory
john dalton
electrons closer to the nucleus have _____ energy than electrons farther away from the nucleus
less
which scientist defined material as radiation?
marie curie
Rutherford's resulting atomic model proposed that most of an atom's _______ and _________ charge is concentrated in the center of the atom
mass, positive
Democritus proposed that different types of ____ are made from different types of atoms
matter
neutron symbol
n
an atom with a negative charge is called a _______
negative icon
neutral particle in the nucleus of an atom
neutron
chadwick discovered the _________, a neutral particle that exists in the ______ of an atom
neutron, nucleus
protons and _____ are made of smaller parts called _____
neutrons, quarks
protons and _____ have about the ______ mass
neutrons, same
more research showed that, although electrons have specific amounts of energy, energy levels are ______ arranged in circular orbits
not
scientists have learned that atoms are _____ the smallest particles of matter
not
a process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation
nuclear decay
small area in the center of an atom in which most of an atom's mass and positive charge is concentrated
nucleas
radiations comes from the ______ of the uranium atoms
nuclei
Most of the mass of an atom is found in its
nucleus
What part of the atom did Rutherford discover?
nucleus
rutherford concluded that most of an atom's mass and positive charge is concentrated in a small area called the ______
nucleus
the ______ is the small, positively charged area in the center of the atom
nucleus
every atom of the same element has the same atomic ________
number
An element is identified by its _______ in the nucleus
number of protons
if you want the number of electrons in an element, what number do you look for on the periodic table
number of protons
proton symbol
p
rutherford expected the _____ ______ ______ to travel straight through the foil without changing direction
positive alpha particles
if a neutral atom gains electrons, it is ______ if it loses electrons its _______
positive, negative
because atoms are neutral, thomson proposed that atoms also must contain a ____ charge that balances the ________ charged electrons
positive, negatively
atomic particle with one positive charge (1+)
proton
atoms of different elements have different amounts of what?
proton
in the nucleus is the _____, which is an atomic particle with one positive charge
proton
when beta decay occurs, a neutron changes into a _________ and a high energy electron called a beta particle. the atomic number of an atom ___________- by one because it has gained a proton.
proton, increases
different elements contain different numbers of ____
protons
the positive charge in the nucleus was made of positively charged particles called ______
protons
of the subatomic particles, which two are attracted to eachother
protons and electrons
Mass number = number of _____ + number of _____
protons and neutrons
the total number of ________ and neutrons in an atoms is the _____ of the atom
protons, mass
protons and neutrons are made of smaller particles called _____
quarks
___________ can be beneficial to humans by destroying harmful cells such as cancer cells
radiation therapy
marie curie called elements that spontaneously emit radiation _____
radioactive
which scientist expiermented with uranium?
rutherford
which scientist said atoms have a nuclueus
rutherford
a _________ microscope enabled scientists to see individual atoms for the first time
scanning tunneling
What kind of microscope can create images of atoms?
scanning tunneling micropscope
what was invented in 1981 that allowed scientists to see indivdual atoms
scanning-tunneling microscope
what were atoms first seen by?
scanning-tunneling microscope (SMT)
the results of rutherfords student's expeirment showed that most particles traveled through the foil, but some bounced to the ____ and a few bounced straight back
side
there are _____ types of quarks
six
the mass of electrons are _______ than the mass of protons and neutrons
smaller
thomson's atomic model stated that an atom is a positively charged ____ with _____ throughout it
sphere, electrons
thomson's proposed atom was a _____ with a positive charge evenly spread throughout and ________ charged electrons within it
sphere, negatively
some alpha particles traveled in a straight path, as expected. but some changed direction and bounced _____ _____
straight back
early scientists were not able to ______ their theories
test
who was the scientist that worked with the cathode ray tubes
thomson
how many carbon atoms are in a period
trillions
what element dud marie curie use to discover radioactive material
uranium
an atomic number has to be a _____ number
whole
