Anonymous
Anonymous asked in Science & MathematicsChemistry · 8 years ago

Proton's mass affects the entire mass of the atom while electron?

And also..If protons determine the atom's identity..how about the electrons?

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  • Dr W
    Lv 7
    8 years ago
    Favorite Answer

    some definitions...

    ATOMIC MASS. is the mass of an atom. It includes the mass of protons, neutrons, electrons, mass defect, etc. This DOES include the mass of electrons !!!! This is NOT found on a periodic table (except for special cases). This is also called "isotopic mass".

    RELATIVE ATOMIC MASS. This is the mass found on a periodic table. It is NOT the mass of any one atom (except for special cases). This is an average mass of all naturally occuring isotopes of the element. It is actually a weighted average mass.

    MASS NUMBER. This is the number of protons + number of neutrons the nucleus. It is NOT a true "mass". It is a counting of protons + neutrons.

    ATOMIC NUMBER. This is the number of protons in a nucleus. If you notice, the periodic table is arranged by increasing numbers of protons.

    ISOTOPES. For a given element, all atoms have the same atomic number and therefore the same number of protons. BUT the number of neutrons is free to vary. We distinguish between atoms of the same element that have different numbers of neutrons with the term "isotope". Different isotopes of the same element have the same number of protons and different numbers of neutrons.

    ********

    And beware... most people misinterpret "relative atomic mass" as "atomic mass" and assume that does not include the mass of electrons. And they assume that equals mass number as well. That is COMPLETELY INCORRECT! They are all different entities and you need to make sure you understand the differences.

    ********

    example...

    http://en.wikipedia.org/wiki/Chlorine

    relative atomic mass = 35.45 AMU per atom

    atomic number = 17

    meaning..

    (1).. ALL chlorine atoms have 17 protons

    (2).. the WEIGHTED AVERAGE mass of naturally occuring chlorine atoms is 35.45 AMU

    and at the bottom of the boxes at the right, you can see that there are essentially 2 naturally occuring isotopes that are used to calculate 35.45 AMU. one with 18 neutrons and 1 with 20 neutrons.

    from here..

    http://en.wikipedia.org/wiki/Isotopes_of_chlorine

    you can see a list of all "isolated' isotopes of chlorine to date.

    (1).. notice all have 17 protons... the Z(p) column

    (2).. notice the number of neutrons varies from 11 to 34... the N(n) column.

    (3).. notice the "MASS NUMBER" located in the nuclide symbol column? That is the # protons + # neutrons and is a whole number.

    (4).. notice the atomic masses? that is the isotopic mass column. NONE are whole numbers... they are not simply # of protons + # neutrons. That is because the total mass of the atom is the mass of protons + neutrons + electrons - mass defect... etc.

    (5).. notice also, there are NO isotopes with atomic mass = 35.45 AMU.. because that is an average number!

    **********

    so to answer your questions..

    yes... the protons mass does affect the mass of the atom

    yes.. the mass of electrons DOES affect the mass of the atom

    NO.. only the # of protons determines the identity of the atom. The number of electrons determines the charge on the atom. IF # electrons = # protons, the atom is neutral. If # electrons ≠ # protons, the atom will have a charge. And we call an atom with a non-zero charge.. an ion.

    ********

    make sense?

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  • 8 years ago

    I'm not quite sure whether your title is a question or a statement; if it is the former, then yes, that is pretty much the case; an electron only has about one twothousandth or so of a proton mass, so the electron masses appear earlist as, say, the second digit after the comma, when the atomic mass is expressed in proton or neutron masses.

    The number of protons dictates the electron structure of the whole atom, as the overall nuclear charge determines the number of electrons necessary for neutrality.

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  • 4 years ago

    Mass is defined in terms of inertia - the need for a force to make something alternate its direction or velocity of motion. Mass and energy are below some occasions interconvertible, as expressed in the equation E = mc^2 however various conditions ought to be satisfied for this to occur big scale. For example, you can't turn an electron into pure power, but an electron and the positron will react to generate energy in the form of a pair of gamma rays (challenge situation for readers: why do you want TWO gamma rays, no longer only one?). The reference to Higgs was once spot-on. This is all very much physics. No person really is aware of, but we've not given up and mustn't quit of finding out fairly a bit of more. BTW, a neutron weighs moderately greater than a proton, and roughly 2000 times as a lot as an electron. That you can calculate the vigour released in a nuclear response by using subtracting the mass of the products from the mass of the dad or mum, and utilising Einstein's system. The mass of a proton involves the mass of the quarks, of the gluons conserving the quarks collectively, and the energy worried.

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  • An electron's mass is negligible as compared to a proton.

    Electron-9.10938188 × 10^-31 kg

    Proton-1.6726 x 10^-27 kg

    so the mass of an electron isn't considered while calculating the mass of an atom

    As for your 2nd question,

    The electrons decide the ionization state of an atom, whether its a neutral atom, a cation(positively charged) or anion(negatively charged). If number of protons=number of electrons, the atom is neutral,

    if number of protons>number of electrons its an anion,

    if number of protons<number of electrons its a cation.

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  • Anonymous
    8 years ago

    Atoms have a nucleus or "middle" made up of protons & neutrons, and have electrons in orbit around that nucleus....each proton has a mass of 1 "atomic mass unit" (AMU), and each neutron has (approximately) the same mass. Electrons, however, have negligible mass in comparison to the protons & neutrons.

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