Ernest Rutherford introduced the nuclear model, which described the atom as containing a small, dense, (positive or negative) charged center surrounded by a (positive or negative) cloud of electrons.
Bohr's model was a miniature solar system in which the electrons revolved about the nucleus in prescribed orbits or _____.
Bohr Atom represents the best way to picture the atom, although the details of atomic structure are more accurately described by a newer model called
quantum chromodynamics (QCD)
"Atom smashers", the structure of the atomic nucleus is slowly being mapped and identified.
The three primary constituents of an atom also known as fundamental particles:
The 3 fundamental particles of an atom are:
very small particles that carry one unit of negative electric charge.
An atomic particle is extremely small, its mass is expressed in
Atomic Mass Unit (amu)
One atomic mass unit is equal to ___ the mass of a carbon-12 atom.
When precision is not necessary, a system of whole numbers used is called
The atomic mass number of an electron is
The nucleus contains particles called
The 2 types of nucleons
Protons and neutrons both have nearly how times the mass of an electron?
Essentially empty space.
The number of protons determines the
Atoms that have the same number of protons but differ in the number of neutrons are
Electrons can exist only in certain ___, which represent different electron binding energies or ____ ____.
For identification purposes, electron orbital shells are given the codes (name 1st four) to represent the relative binding energies of electrons from closest to the nucleus to farthest from the nucleus
K, L, M, N
The closer an electron is to the nucleus, what energy is greater?
What are electrically neutral in their normal state?
The removal or addition of an orbital electron from an atom
The mass number of electrons that can exist in each shell (decrease or increase) with the distance of the shell from the nucleus.
The total number of electrons in the orbital shells is exactly equal to the number of ____ in the _____
An atom has an extra electron or has had an electron removed is
An ionized atom is not electrically neutral but carries a charge equal in magnitude to the difference between the numbers of ____ and ____
How the maximum electrons per shell is calculated
What is the maximum number of electrons that can exist in the O shell (shell number 5)
n = 5
2n2 = 2(5)2 = 2 (25)
= 50 electrons
What is the shell number for each symbol:
K, L, M, N, O, P, Q
K = shell 1
L = shell 2
M = shell 3
N = shell 4
O = shell 5
P = shell 6
Q = shell 7
Calculate the number of electrons that can occupy each electron shell for the following: 2n2
K, L, M, N
K = 2(12)
= 2(1) = 2 electrons
L = 2(22)
= 2(4) = 8 electrons
M = 2(32)
=2(9) = 18 electrons
N = 2(42)
= 2(16) = 32 electrons
No outer shell can contain more than ____ electrons
What does Physicists call the shell number n
principal quantum number
"center-seeking" force, which results from a basic law of electricity that states that opposite charges attract one another and like charges repel.
The force that keeps an electron in orbit is
The strength of attachment of an electron to the nucleus is called
electron binding energy
K-shell electrons have higher binding energies than L-shell electrons, L-shell electrons are more tightly bound to the nucleus than M-shell electrons, and so forth.
The atomic mass number and the precise mass of an atom are (equal or not equal)
A whole number that is equal to the number of nucleons in the atom
atomic mass number
The characteristic mass of an element is determined by the relative abundance of isotopes and their perspective atomic masses
Atoms that have the same atomic number but different atomic mass numbers are
Atomic nuclei that have the same atomic mass number but different atomic numbers are
The atoms that have different numbers of protons and different numbers of neutrons but the same total number of nucleons
Atoms that have the same number of neutrons but different numbers of protons are
Atoms with different atomic numbers and different mass numbers but a constant value for the quantity A-Z.
Atoms with the same number of neutrons in the nucleus
Have the same atomic number and the same atomic mass number.
Atoms of various elements may combine to form structures called
Any quantity of one type of molecule
Similarly, hydrogen, oxygen, carbon, and nitrogen compose more than ____% of the human body.
At approximately what % water molecules make up of the human body?
Oxygen and hydrogen combine into water through what type of bonds.
Sodium and chlorine combine into salt through what type of bond?
A measurable quantity of sodium bicarbonate constitutes a chemical compound commonly called
Some atoms exist in an abnormally excited state characterized by an unstable nucleus. To reach stability, the nucleus spontaneously emits particles and energy and transform itself into another atom. This process is called _____ _____ or _____ _____
Any nucleus that emits radiation; Only nuclei that undergo radioactive decay are
Process by which the nucleus spontaneously emits particles and energy and transforms itself into another atom to reach stability.
Naturally occurring process whereby an unstable atomic nucleus relieves its instability through the emission of one or more energetic particles
Any nuclear arrangement; General term that refers to all known isotopes, both stable and unstable, of chemical chemical elements
The emission of particles and energy in order to become stable
In addition to stable isotopes, many elements have ____; these may be artificially produced in machines such as particle accelerators or nuclear reactors.
Two ways radioisotopes can decay to stability; Radioactive decay by positron emission is important for some nuclear medicine imaging.
An electron created in the nucleus is ejected from the nucleus with considerable kinetic energy and escapes from the atom
Much more violent process; Alpha particle consist of two protons and two neutrons bound together; Its atomic mass number is 4
What results in emission of alpha particles, beta particles, and usually gamma rays?
The rate of radioactive decay and the quantity of material present at any given time are described mathematically by a formula know as the
Radioactive decay law
From the radioactive decay law, what is this formula (T 1/2)
What radioisotopes vary from less than a second to many years. Each radioisotope has a unique, characteristic half-life?
Used daily in nuclear medicine and has an exact parallel in x-ray terminology
3.3 half lives =
1 tenth life
How many half-lives are required before a quantity of radioactive material has decayed to less than 1% of its original value?
Half-life number Radioactivity remaining
1 50% (half of 100%)
2 25% (half of 50)
3 12.5% (half of 25)
4 6.25% (half of 12.5)
5 3.12% (half of 6.25)
6 1.56% (half of 3.12)
7 0.78% (half of 1.56)
Two main types of particulate radiation; Both are associated with radioactive decay.
Equivalent to a helium nucleus, contains 2 protons and 2 neurtons, its mass is approx 4 amu, and it carries 2 units of positive electric charge
Because of the amount of ionization, the energy of an alpha particle is quickly lost. It has a very short range in matter. Whereas in air, alpha particles can travel approx 5 cm; in soft tissue, the range may be less than 100 um
An electron emitted from the nucleus of a radioactive atom; they are light particles with an atomic mass number of 0 and carry one unit of negative or positive charge.
All ionizing radiation can be conveniently classified into two categories:
The types of radiation used in diagnostic ultrasonography and in magnetic resonance imaging are
Depending on its energy, a beta particle may traverse ___ to ___ cm of air and approximately __ to __ cm of soft tissue.
10 to 100 cm of air
1 to 2 cm of soft tissue
Type of rays that are forms of electromagnetic ionizing radiation
X-rays and gamma rays are often called
What have no mass and no charge & they travel at the speed of light? (c = 3 x 108 m/s) and are considered energy disturbances in space.
What rays exist at the speed of light or not at all?
Characteristics of Various Nuclear Arrangements (Table 2-4) page 36
A method of association to help with the "iso" definitions is:
isotope, same proton
isobar, same A (Atomic Mass Number)
isotone, same neutron
isomer, metastable (all are the same)
As a miniature solar system, what set the stage for the modern interpretation of the structure of matter?
What is the smallest part of an element? and what is the smallest part of a compound?
Negatively charged particles that orbit the nucleus in configurations or shells held in place by electorstatic forces.
Reaction that occur when outermost orbital electrons are shared or given up to other atoms.
Positively charged, and neutrons have no charge
What are grouped in a periodic table in order of increasing complexity; The groups on the table indicate the number of electrons in the outermost shell.
Some atoms, which contain too many or too few neutrons in the nucleus, can disinergrate, this is called
What is a radioisotope is the time required for the quantity of radioactivity to be reduced to one-half its origianl value
Rays that are produced in the electron shells
Rays that are emitted from the nucleus of a radioiosotope
This particle originate in the nucleus of radioactive atoms
The electric charge on the atom is ____
What is the smallest particle that has all the properties of an element?
What is the center of the atom?
particle accelerators =
Only the 3 primary constituents of atom, the electron, the proton,and the nuetron, are considered here. They are the ______ ______.
The fundamental particles of an atom are the electron, the proton, and the neutron.
_________ are very small particles that carry one unit of negative electric charge
Because an atomic particle is extremely small, its mass is expressed in _____ _____ _____ for convienence.
Atomic mass units (AMU)
When precision is not necessary, a system of whole numbers called atomic mass _______ is used.
The atomic mass number of an electron is
The nucleus contains particles called ______, of which there are 2 types: protons & neutrons. Both have nearly 2000 times the mass of the electron.
The atom is essentially empty space
The number of protons determines the _______ ______. Atoms that have the same number of protons but differ in the number of neutrons are isotopes; they behave the same way during chemical reactions.
Electrons can exist only in certian shells, which represent different _______ _______ _______ or energy levels.
electron binding energies
In their normal state atoms are electrically _______, the electric charge on the atoom is zero.
If an atom has an extra electron or has had an electron removed, it is said to be ________.
Ionization is the removal or addition of an orbital electron from an atom.
The maximum number of _______ that can exist in each shell increases with the distance of the shell from from the nucleus.
Maximum electrons per shell can be calculated by:
NO outer shell can contain more than ____ electrons
_________ force; is a force theat keeps an electron in orbit
the force that keeps an electron in orbit is __________
The _____ _____ causes an electron to travel straight and leave the atom.
The centrifugal force makes sure that the electrons maintain their distance from the nucleus while traveling in a circular path.
The strength of attachment of an electron to the nucleus is called the _____ _____ _____.
electron binding energy
The closer an electron is to th nucleus, the more tightly it is bound. K shell elcetrons have higher binding energies than L shell electrons. L more than M and so forth
The Atomic Mass number and the precise mass of an atom are not equal.
Any nuclear arrangement is called a _____?
Radioactivity is the emission of particles and energy in order to become stable