Examples of Avogadro's number in the following topics:
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- The number of molecules in a mole is called Avogadro's number (NA)—defined as 6.02x 1023 mol-1.
- The actual number of atoms or molecules in one mole is called Avogadro's constant (NA), in recognition of Italian scientist Amedeo Avogadro .
- Avogadro's number (N) refers to the number of molecules in one gram-molecule of oxygen.
- The value of Avogadro's constant, NA , has been found to equal 6.02×1023 mol−1.
- Avogadro's constant is a scaling factor between macroscopic and microscopic (atomic scale) observations of nature.
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- where C is a constant which is directly proportional to the amount of gas, n (representing the number of moles).
- where k is Boltzmann's constant and N is the number of molecules.
- (Since N = nNA, you can see that $R = N_Ak$, where NA is Avogadro's number. )
- where P is the pressure, N is the number of molecules, m is the mass of the molecule, v is the speed of molecules, and V is the volume of the gas.
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- By noting that N=NAn and R = kNA (NA: Avogadro's number, R: universal gas constant), we derive:
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- English chemist John Dalton (1766-1844) did much of this work, with significant contributions by the Italian physicist Amedeo Avogadro (1776-1856).
- It was Avogadro who developed the idea of a fixed number of atoms and molecules in a mole.
- This special number is called Avogadro's number in his honor ($6.022 \cdot 10^{23}$).
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- The following table shows all possibilities along with numbers of possible configurations (or microstate; a detailed description of every element of a system).
- The total number of different ways 100 coins can be tossed—is an impressively large 1.27×1030.
- The fantastic growth in the odds favoring disorder that we see in going from 5 to 100 coins continues as the number of entities in the system increases.
- In a volume of 1 m3, roughly 1023 molecules (or the order of magnitude of Avogadro's number) are present in a gas.
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- A round-off error is the difference between the calculated approximation of a number and its exact mathematical value.
- Calculations rarely lead to whole numbers.
- The number $\pi$ (pi) has infinitely many digits, but can be truncated to a rounded representation of as 3.14159265359.
- However, when doing a series of calculations, numbers are rounded off at each subsequent step.
- Rounding these numbers off to one decimal place or to the nearest whole number would change the answer to 5.7 and 6, respectively.
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- Scientific notation is a way of writing numbers that are too big or too small in a convenient and standard form.
- In scientific notation all numbers are written in the form of $a\cdot 10^{b}$ ($a$ multiplied by ten raised to the power of $b$), where the exponent $b$ is an integer, and the coefficient $a$ is any real number.
- Each number is ten times bigger than the previous one.
- Continuing on, we can write $10^{-1}$ to stand for 0.1, the number ten times smaller than $10^{0}$.
- Negative exponents are used for small numbers:
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- Through radioactive decay, nuclear fusion and nuclear fission, the number of nucleons (sum of protons and neutrons) is always held constant.
- In physics and chemistry there are many conservation laws—among them, the Law of Conservation of Nucleon Number, which states that the total number of nucleons (nuclear particles, specifically protons and neutrons) cannot change by any nuclear reaction.
- Electron capture has the same effect on the number of protons and neutrons in a nucleus as positron emission.
- Finally, nuclear fusion follows the Law of Conservation of Nucleon Number.
- Thus, the number of nucleons before and after fission and fusion is always constant.
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- The stability of an atom depends on the ratio and number of protons and neutrons, which may represent closed and filled quantum shells.
- The stability of an atom depends on the ratio of its protons to its neutrons, as well as on whether it contains a "magic number" of neutrons or protons that would represent closed and filled quantum shells.
- Of the 254 known stable nuclides, only four have both an odd number of protons and an odd number of neutrons:
- All elements form a number of radionuclides, although the half-lives of many are so short that they are not observed in nature.
- An atomic nucleus emits an alpha particle and thereby transforms ("decays") into an atom with a mass number smaller by four and an atomic number smaller by two.
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- In alpha decay an atomic nucleus emits an alpha particle and transforms into an atom with smaller mass (by four) and atomic number (by two).
- As the result of this process, the parent atom transforms ("decays") into a new atom with a mass number smaller by four and an atomic number smaller by two.
- Because an alpha particle is the same as a helium-4 nucleus, which has mass number 4 and atomic number 2, this can also be written as:
- The lightest known alpha emitters are the lightest isotopes (mass numbers 106-110) of tellurium (element 52).
- An atomic nucleus emits an alpha particle and thereby transforms ("decays") into an atom with a mass number smaller by four and an atomic number smaller by two.