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The number of neutrons, N, is known as the neutron number of the atom ; thus, A = Z + N. Since protons and neutrons have approximately the same mass ( and the mass of the electrons is negligible for many purposes ), and the mass defect is usually very small compared to the mass, the atomic mass of an atom is roughly equal to A.
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number and neutrons
The atomic number, Z, should not be confused with the mass number, A, which is the number of nucleons, the total number of protons and neutrons in the nucleus of an atom.
In general, the half-life becomes shorter as atomic number increases, though an " island of stability " may exist for undiscovered isotopes with certain numbers of protons and neutrons.
An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determines the isotope of the element.
This can result in a transmutation that changes the number of protons or neutrons in a nucleus.
Isotopes were then explained as elements with the same number of protons, but different numbers of neutrons within the nucleus.
Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle ( two protons and two neutrons ) and thereby transforms ( or ' decays ') into an atom with a mass number 4 less and atomic number 2 less.
Although all the nuclei of all atoms belonging to one element will have the same number of protons, they may not necessarily have the same number of neutrons ; such atoms are termed isotopes.
The number of neutrons in a nucleus usually has very little effect on an element's chemical properties ( except in the case of hydrogen and deuterium ).
Thus, all carbon isotopes have nearly identical chemical properties because they all have six protons and six electrons, even though carbon atoms may differ in number of neutrons.
The mass number of an element, A, is the number of nucleons ( protons and neutrons ) in the atomic nucleus.
number and N
The completeness of the connections provide that, for N people, there are Af lines of communication between the pairs, which can become a large number ( 1,225 ) for a party of fifty guests.
The approximate equation is Af, where N is the number of Af with electron line-density greater than or equal to Af, and Q is proportional to the mass of the meteorite.
Each performance of an n-trial binomial experiment results in some whole number from 0 through N as the value of the random variable X, where Af.
Atoms having the same atomic number Z but different neutron number N, and hence different atomic mass, are known as isotopes.
In number theory, if P ( n ) is a property of positive integers, and if p ( N ) denotes the number of positive integers n less than N for which P ( n ) holds, and if
For example, the prime number theorem states that the number of prime numbers less than or equal to N is asymptotically equal to N / ln N. Therefore the proportion of prime integers is roughly 1 / ln N, which tends to 0.
Dial + 64 ( 8 ) 320-1231, from USA / Canada and rest of NANP dial 011-64-8-320-1231 to hear your 3 digit area code & 7 digit local number read back to you from N. Z.
The national roads are marked with a letter N and a number.
The Boltzmann distribution for the fractional number of particles N < sub > i </ sub > / N occupying a set of states i possessing energy E < sub > i </ sub > is:
number and is
It is one of the ironic quirks of history that the viability and usefulness of nationalism and the territorial state are rapidly dissipating at precisely the time that the nation-state attained its highest number ( approximately 100 ).
It is worth dwelling in some detail on the crisis of this story, because it brings together a number of characteristic elements and makes of them a curious, riddling compound obscurely but centrally significant for Mann's work.
The cyclist, a sufficiently commonplace young fellow, is not named but identified simply as `` Life '' -- that and a license number, which Piepsam uses in addressing him.
Presumably a cocktail party is expected to fulfill the host's desire to get together a number of people who are inadequately acquainted and thereby arrange for bringing the level of acquaintance up to adequacy for future cooperative endeavors.
The number of primitive ideas in systematically-simple theories is reduced to a minimum.
I assume that the number of readers of this anthology who regard themselves as morally perfect is small, and that most readers are willing to consider procedures by which they may gain more insight into themselves and better understanding of others.
That is how the real routine of resistance goes on, and its strength is directly proportionate to the number of insignificant people who can let themselves be taken to pieces, piece by piece, without quitting.
Although the United States and the U.S.S.R. have been arguing whether there shall be four, five or six top assistants, the most important element in the situation is not the number of deputies but the manner in which these deputies are to do their work.
There are a number of other considerations besides this one but it is for the Congress, not the Department of Justice, to balance these various considerations and make a judgment about legislation.
Nonetheless, although few in number they are a stubborn crew, as tenacious of life as the Hardshell Baptists, which suggests that there is some kind of vital principle embodied in their faith.
For that is the one an increasingly large number of prominent Americans are now proposing.
and it is still very far from certain how valid the party's claim is that in `` a growing number of kolkhozes '' the peasants are finding it more profitable, to surrender their private plots to the kolkhoz and to let the latter be turned into something increasingly like a state farm.
Too bad your number is in the directory ''.
The number of countries thus favorably situated is small, but their peoples constitute over half of the population of the underdeveloped world.
The resulting setup, it was declared, `` would be similar to that which is in successful operation in a number of metropolitan counties as large or larger than Rhode Island ''.
The Navy, on April 25, announced it is bringing back the carrier Shangri-La from the Mediterranean, increasing to four the number of attack carriers in the vicinity of Cuba.
There is little doubt that the number of those who wish to serve will be far greater than our capacity to absorb them.
Since broadcast frequencies are very limited in number, these objectives are to some extent inconsistent in that not all of them can be fully realized, and to the extent that each is realized, there is a corresponding reduction of the possibilities for fullest achievement of the others.
During nighttime hours, because of the intense skywave propagation then prevailing, no large number of stations can be permitted to operate on one of these channels, if the wide area service for which these frequencies are assigned is to be rendered satisfactorily by the dominant stations which must be relied upon to render it.
In the daytime, on the other hand, since skywave transmission is relatively inefficient, it is possible to assign a substantially larger number of stations on these channels.
Such additional daytime class 2, assignments are appropriate if optimum use is to be made of these frequencies, and the Commission has over the years made a large number of them.
number and known
The total number of known amphibian species is approximately 7, 000, of which nearly 90 % are frogs.
The numbers of species cited above follow Frost and the total number of known amphibian species is approximately 7, 000, of which nearly 90 % are frogs.
In chemistry and physics, the atomic number ( also known as the proton number ) is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus.
This placement is consistent with the modern practice of ordering the elements by proton number, Z, but this number was not known or suspected at the time.
Another problem was that the gradual identification of more and more chemically similar and indistinguishable lanthanides, which were of an uncertain number, led to inconsistency and uncertainty in the numbering of all elements at least from lutetium ( element 71 ) onwards ( hafnium was not known at this time ).
Nevertheless, in spite of Rutherford's estimation that gold had a central charge of about 100 ( but was element Z = 79 on the periodic table ), a month after Rutherford's paper appeared, Antonius van den Broek first formally suggested that the central charge and number of electrons in an atom was exactly equal to its place in the periodic table ( also known as element number, atomic number, and symbolized Z ).
The former represents a choice between a finite number of known and meaningful context-dependent interpretations.
Only a limited number of actinium compounds are known including AcF < sub > 3 </ sub >, AcCl < sub > 3 </ sub >, AcBr < sub > 3 </ sub >, AcOF, AcOCl, AcOBr, Ac < sub > 2 </ sub > S < sub > 3 </ sub >, Ac < sub > 2 </ sub > O < sub > 3 </ sub > and AcPO < sub > 4 </ sub >.
Until these experiments, atomic number was not known to be a physical and experimental quantity.
Ceremonial structures known as kivas were built in proportion to the number of rooms in a pueblo.
Throughout the southwest Ancient Puebloan region and at Mesa Verde, the best known site for these large number of well preserved cliff dwellings, housing, defensive and storage complexes were built in shallow caves and under rock overhangs along canyon walls.
In the quantum picture of Heisenberg, Schrödinger and others, the Bohr atom number n for each orbital became known as an n-sphere in a three dimensional atom and was pictured as the mean energy of the probability cloud of the electron's wave packet which surrounded the atom.
Vessels may carry a number of anchors: bower anchors ( formerly known as sheet anchors ) are the main anchors used by a vessel and normally carried at the bow of the vessel.
Computer programs, known as " anagram servers ", " anagram solvers " or " anagrammers ", offer a much faster route to creating anagrams, and a large number of these programs are available on the Internet.
Additionally, the Lombards would have known of the weakness of Byzantine Italy, which had endured a number of problems after being retaken from the Goths.
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