an area around the atomic nucleus in which an electron is likely to be located
electron cloud
An electron cloud is mostly ________ space.
empty
Protons and neutrons are made of smaller parts called _______.
quarks
There are ______ types of quarks.
6
The limitation of Bohr's model is that electrons do not actually move in ________ orbits.
circular
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 level
The atomic model of __________ proposed that electrons move in circular orbits, or , energy levels around the nucleus.
Bohr
____________ was one of Rutherford's colleagues.
James Chadwick
Chadwick discovered the ______________, a neutral particle that exists in the nucleus of an atom.
neutron
In the nucleus is the ________, which is an atomic particle with one positive charge.
proton
The _________ is the small, positively charged area in the center of the atom.
nucleus
Rutherford's resulting atomic model proposed that most of an atom's ________ and positive charge is concentrated in the center of the atom.
mass
The results showed that most of the particles traveled through the foil, but some bounced to the ________, and a few bounced straight back.
side
Rutherford's student performed an experiment during which they shot __________ particles into a piece of gold foil.
alpha
Thomson's atomic model stated that an atom is a positively charged _________ with negative charges throughout it.
sphere
Thomson discovered that the rays in a(n) ________ were attracted to a(n) positively charged plate, which means that the rays have a(n) negative charge.
cathode
Atoms were first seen by using a(n) _______ microscope.
STM
A(n) __________ is the smallest piece of an element that still represents that element.
atom
John Dalton proposed the ___________ theory, which was based on careful observations and measurements of chemical reactions.
atomic
Dalton's theory states that atoms cannot be divided, __________, or destroyed.
created
It also stated that atoms of one _________ are different from atoms of other __________.
element; elements
Many ancient Greek philosophers thought that all matter was made of only four elements�fire, water, air, and _______.
earth
These early scientists were not able to __________ their theories.
test
Democritus proposed that matter is made of small, indivisible objects called _________.
atoms
He proposed that different types of _______ are made from different types of atoms.
matter
who discovered the nucleus?
rutherford
The Parts of the Atom
proton, neutron, electron
how many protons are in each atom?
every atom has its own number of protons
Atomic Number
the number of protons in an atom of an element
Isotopes
an element with a different number of neutrons
Atomic Mass
average atomic mass of these isotopes
Radioactive
elements that spontaneously emit radiation
Nuclear decay
a process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation
Beta Decay
one fewer neutron and one more proton
Alpha Decay
two fewer protons and neutrons
Gamma Decay
no change in protons and neutrons
Ion
an atom that is no longer neutral because it has gained or lost electrons
Democritus (370 BC)
- Atoms are small solid objects that cannot be divided, created, or destroyed; law of conservation
-Atoms are constantly moving in empty space
- Different types of matter are made of different types of atoms
- The properties of atoms determine the propert
Aristotle
- matter was made of water, fire, earth, air
- didn't believe that empty space existed
Dalton's Atomic Model (1766)
- all matter is made of atoms that can not be divided, created, or destroyed; law of conservation
- during a chemical reaction, atoms of one element can not be converted into atoms of another element
- atoms of one element are identical to each other, but
Thomson --- Discovering Electrons (1856)
- model of an atoms contains a positively charged sphere
- the sphere is filled with negatively charged electrons within it
Rutherford's Predicted Results
- alpha particles would be sent through gold foil nucleus
- a light would project through the gold electrons to opposite end
Rutherford's Surprising Result
- particles bounced backward being deflected by the electrons within the foil
- each gold foils was made of gold atoms made of a nucleus surrounded by electrons that deflected the alpha particles
Rutherford's Atomic Model
- small dense, positive, nucleus
- tiny negatively charged electrons travel in empty space around the nucleus
Bohr's Atomic Model (1913)
- electrons travel in circular orbit around the nucleus
- when an electron moves from a higher energy level to a lower energy level, energy is released as light
- electrons are not arranged in orbits
Quarks
particles that make up protons and neutrons in the nucleus
Protons and neutrons have about the same _______.
mass
___________ have much less mass than the other two particles in an atom.
electrons
Most of the mass of an atom is in the _______.
nucleus
The number of protons in an atom of an element is the element's __________.
atomic number
Different elements contain different numbers of __________.
protons
In a neutral atom, the number of _____________ equals the number of protons because the number of negative charges must equal the number of positive charges.
electrons
____________ are atoms of the same element that have different numbers of neutrons.
isotopes
The total number of protons and neutrons in an atom is the ____________ of the atom.
mass number
The average __________ of an element is the average mass of the element's isotopes.
atomic mass
The average atomic mass is __________ according to the abundance of each isotope.
weighted
Marie Curie called elements that spontaneously emit radiation __________.
radioactive
Radiation is made of energy and ____________ that come from the nuclei of radioactive atoms.
particles
When atoms release particles of radiation, they change to different ____________.
elements
___________ is a process that occurs when an unstable atomic nucleus changes into another, more stable nucleus by emitting radiation.
Nuclear decay
Nuclear decay can produce three different types of ___________.
radiation
A(n) _________ particle consists of two protons and two neutrons.
alpha
When alpha decay occurs, the atomic number of each atom that decays decreases by ____________.
two
_________ decay occurs when a neutron in an atom changes into a(n) and a high-energy electron called a(n) __________ particle.
beta; beta
When beta decay occurs, the atomic number of an atom increases by ________.
one
Gamma rays contain a lot of energy but no __________.
particles
_________ rays are sometimes emitted during nuclear decay, but this decay does not change one element into another element.
gamma
Energy released during radioactive decay can be either ____________ or harmful.
beneficial
A(n) _______ is an atom that is no longer neutral because it has gained or lost electrons.
ion
A positive ion is an atom that has ________ electrons.
less
A negative ion is an atom that has ______ electrons.
more
__________ first noticed that some elements spontaneously give off energy.
Henri Becquerel
Weighted means that the average atomic mass is based on the _______ of each atom in a sample and the number of atoms of that ________ that are present.
isotopes; isotopes
When the _________ in an atom change, it gives off radioactivity.
protons
an area around the atomic nucleus in which an electron is likely to be located
electron cloud
An electron cloud is mostly ________ space.
empty
Protons and neutrons are made of smaller parts called _______.
quarks
There are ______ types of quarks.
6
The limitation of Bohr's model is that electrons do not actually move in ________ orbits.
circular
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 level
The atomic model of __________ proposed that electrons move in circular orbits, or , energy levels around the nucleus.
Bohr
____________ was one of Rutherford's colleagues.
James Chadwick
Chadwick discovered the ______________, a neutral particle that exists in the nucleus of an atom.
neutron
In the nucleus is the ________, which is an atomic particle with one positive charge.
proton
The _________ is the small, positively charged area in the center of the atom.
nucleus
Rutherford's resulting atomic model proposed that most of an atom's ________ and positive charge is concentrated in the center of the atom.
mass
The results showed that most of the particles traveled through the foil, but some bounced to the ________, and a few bounced straight back.
side
Rutherford's student performed an experiment during which they shot __________ particles into a piece of gold foil.
alpha
Thomson's atomic model stated that an atom is a positively charged _________ with negative charges throughout it.
sphere
Thomson discovered that the rays in a(n) ________ were attracted to a(n) positively charged plate, which means that the rays have a(n) negative charge.
cathode
Atoms were first seen by using a(n) _______ microscope.
STM
A(n) __________ is the smallest piece of an element that still represents that element.
atom
John Dalton proposed the ___________ theory, which was based on careful observations and measurements of chemical reactions.
atomic
Dalton's theory states that atoms cannot be divided, __________, or destroyed.
created
It also stated that atoms of one _________ are different from atoms of other __________.
element; elements
Many ancient Greek philosophers thought that all matter was made of only four elements�fire, water, air, and _______.
earth
These early scientists were not able to __________ their theories.
test
Democritus proposed that matter is made of small, indivisible objects called _________.
atoms
He proposed that different types of _______ are made from different types of atoms.
matter
who discovered the nucleus?
rutherford
The Parts of the Atom
proton, neutron, electron
how many protons are in each atom?
every atom has its own number of protons
Atomic Number
the number of protons in an atom of an element
Isotopes
an element with a different number of neutrons
Atomic Mass
average atomic mass of these isotopes
Radioactive
elements that spontaneously emit radiation
Nuclear decay
a process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation
Beta Decay
one fewer neutron and one more proton
Alpha Decay
two fewer protons and neutrons
Gamma Decay
no change in protons and neutrons
Ion
an atom that is no longer neutral because it has gained or lost electrons
Democritus (370 BC)
- Atoms are small solid objects that cannot be divided, created, or destroyed; law of conservation
-Atoms are constantly moving in empty space
- Different types of matter are made of different types of atoms
- The properties of atoms determine the propert
Aristotle
- matter was made of water, fire, earth, air
- didn't believe that empty space existed
Dalton's Atomic Model (1766)
- all matter is made of atoms that can not be divided, created, or destroyed; law of conservation
- during a chemical reaction, atoms of one element can not be converted into atoms of another element
- atoms of one element are identical to each other, but
Thomson --- Discovering Electrons (1856)
#NAME?
Rutherford's Predicted Results
#NAME?
Rutherford's Surprising Result
#NAME?
Rutherford's Atomic Model
#NAME?
Bohr's Atomic Model (1913)
#NAME?
Quarks
particles that make up protons and neutrons in the nucleus
Protons and neutrons have about the same _______.
mass
___________ have much less mass than the other two particles in an atom.
electrons
Most of the mass of an atom is in the _______.
nucleus
The number of protons in an atom of an element is the element's __________.
atomic number
Different elements contain different numbers of __________.
protons
In a neutral atom, the number of _____________ equals the number of protons because the number of negative charges must equal the number of positive charges.
electrons
____________ are atoms of the same element that have different numbers of neutrons.
isotopes
The total number of protons and neutrons in an atom is the ____________ of the atom.
mass number
The average __________ of an element is the average mass of the element's isotopes.
atomic mass
The average atomic mass is __________ according to the abundance of each isotope.
weighted
Marie Curie called elements that spontaneously emit radiation __________.
radioactive
Radiation is made of energy and ____________ that come from the nuclei of radioactive atoms.
particles
When atoms release particles of radiation, they change to different ____________.
elements
___________ is a process that occurs when an unstable atomic nucleus changes into another, more stable nucleus by emitting radiation.
Nuclear decay
Nuclear decay can produce three different types of ___________.
radiation
A(n) _________ particle consists of two protons and two neutrons.
alpha
When alpha decay occurs, the atomic number of each atom that decays decreases by ____________.
two
_________ decay occurs when a neutron in an atom changes into a(n) and a high-energy electron called a(n) __________ particle.
beta; beta
When beta decay occurs, the atomic number of an atom increases by ________.
one
Gamma rays contain a lot of energy but no __________.
particles
_________ rays are sometimes emitted during nuclear decay, but this decay does not change one element into another element.
gamma
Energy released during radioactive decay can be either ____________ or harmful.
beneficial
A(n) _______ is an atom that is no longer neutral because it has gained or lost electrons.
ion
A positive ion is an atom that has ________ electrons.
less
A negative ion is an atom that has ______ electrons.
more
__________ first noticed that some elements spontaneously give off energy.
Henri Becquerel
Weighted means that the average atomic mass is based on the _______ of each atom in a sample and the number of atoms of that ________ that are present.
isotopes; isotopes
When the _________ in an atom change, it gives off radioactivity.
protons