What is the rest mass of a proton?
95148
Actually, the mass of a proton is 1.00727664669 atomic mass units.\n\nAn atomic mass unit is defined such that Carbon 12 is exactly 12.  The carbon atom weighs less than 12 times the proton (because of nuclear binding energy).
450990
The mass of a nucleus indicates the number of protons and neutrons present in the nucleus. An element can have more than one isotope eg Carbon 12 and Carbon 14. The former has 6 protons and 6 neutrons, The latter 6 protons and 8 neutrons. \n\nThe atomic weight of an isotope refers to the numbers of protons AND neutrons present. The atomic number of an element refers to the number of protons in all its isotopes.\n\nHydrogen, though normally just a solo proton in its nucleus, does have two isotopes, deuterium, with 1 neutron, and tritium with two neutrons.\n\nA recent question asked about silver, how many of each in its nucleus. Its atomic number is 47, so clearly 47 protons. Naturally-occurring silver is given as having  an atomic weight of 108, so answerers answered 61 neutrons.\n\nHowever there is a subtlety they missed..\n\nNaturally-occurring silver is a mixture of Ag 107 (60 neutrons) and Ag 109 (62 neutrons). (Slightly more than 50% of the former.).\n\nSo the average atomic weight of the two isotopes is 108. But there is no Ag 108 isotope present. The wrong inference was drawn.\n\nSeveral people above are confusing atomic weight and atomic number, and what they each mean. So if you don't understand several of the answers it is because they are jumbled versions of the true picture.
254116
"mathematician" is correct.\n\nAny atom of a given element will have the same number of protons in its nucleus.  If the atom is neutral (i.e. has no charge), then it will have the same number of electrons as protons.\nHowever, the number of neutrons in the nucleus can vary slightly from atom to atom for a given element.  Atoms of the same element but with different numbers of neutrons in their nucleus are called isotopes.  With a greater/less number of neutrons, the over all atomic weight of the atom will varry.  By taking into account the naturally occuring percentages of each of these isotopes of a given element, we can obtain the average atomic mass of all the atoms of that element.\n\nCommon isotopes you might hear would be, "Carbon-12" or "Carbon-14", these are two different isotopes of the element Carbon.  The -# after the element name indicates the total atomic mass of the atom.  Since we know that Carbon always has 6 protons, we can easily determine the number of neutrons if we know the atomic mass.
1138448
Look on a periodic table.\n\nIt should be listed below the atomic number as a decimal value.  The mass number is an average mass (in atomic mass units) of an element, based on different isotopes.  It equals the number of protons + the number of neutrons in the nucleus.
422248
For the time being, we do not know if quarks themselves haveany volume at all. If they, do, the best answer I can give (if we forget the interactions that bind them - which may be a big mistake or not, for there are many more quarks in a proton, than the commonly known 3), the radius of a quark is less than 10^-19m, let's say that it is equal to that, say we have a ball with a radius of 1cm=10^-2 m, making it 10^17 times bigger (linear measurement) So going into  volumes, we get 10^51, which is my approximation.
482427
The "atomic" number refers to the place in the periodic table which corresponds directly (is equal to) the number of protons. The mass number is a weighted average involving commonly found isotopes.
1065678
Atomic weight (243)-94 protons in plutonium=149 neutrons\nAtomic weight= protons + neutorons. This atom has 94 electrons becuase it is not an ion. When an atom is not an ion the protons will equal the electrons.
177569
All of the mass of the respective particles is converted into energy (radiation) according to E=MC^2. Find the mass of the particle you are interested in like a proton. The antiparticle (antiproton) is the same mass. \nA proton weighs 1.672622089*10^-27 kg (M)\nAn antiproton weighs the same.\nThe speed of light in vacuum (C) is 2.9979*10^8 m/s\nThe answer (E) is in J or W. I´m sure you can take it from here. \nYou might want to consider the much smaller energy unit of electronvolt (eV) when working with energy levels for individual particles. 1 eV = 1.602*10^-19 J\n\nA neutron (and an antineutron) weighs 1.674928579*10^-27 kg\nAn electron (and positron) weighs 9.109390332*10^-31 kg\nKnock your self out!
78293
The positions of the protons is relative. You have to have a standard to compare to.\nThe standard is TMS, tetramethyl silane which is given the position of 0 ppm.  Then all protons will show up downfield between 0-13 ppm.
1075835
20.\n\n40 - 20 = 20.\n\nThe mass number is the number of protons and neutrons combined. The atomic number is the number of protons.
199003
a proton has a weight of approximately 1836.15 electrons
405474
This is the rest energy of a particle. Energy equals mass times the speed of light in a vacuum squared. This expression became famous for its simplicity, even though it's not really all that practical. I read once that even at absolute zero particles will still have some motion. I'm not sure how one would go about proving that since it's impossible to get anything to a temperature of absolute zero. Anyway since there will always be some movement, the more practical version is:\n\nE = mc^2 /(sqrt(1 - v^2/c^2)), where v is the speed of the particle. (sqrt() is meant to mean the square root of the argument inside the parenthesis)\n\nIt's important to note that this is only true for a particle since you have to consider binding energies if you want to look at anything more complex.
710178
λ = h/m*v\n\nwhere h the Planck's constant, m the mass of the proton and v its velocity
331142
If you sum up the masses of individual neutrons, protons and electrons in an atom and compare it to the mass of the atom itself you will find it to be slightly higher. This difference in mass is called mass defect. The 'missing' mass is actually the energy required to bring together the individual protons, neutrons, electrons to form the atom. Energy can be calculated using Einstein's formula E= mc^2, where E- energy, m-mass defect, c-speed of light
593336
http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html
664696
The atomic number is equal to the number of electrons in the atom - therefore there are 28.However, since you have a postive 3 charge, there must only be 25.\nNow normally, the number of electrons would equal the number of protons, but since you have a charge of +3, that means that there are three less electrons than protons(you don't lose protons until you get into radioactivity, and it doesn't soung like you're there yet), so that means that you have 25 electrons and 28 protons.\nThe atomic mass is defined as the number of protons + the number of neutrons, so you have 60 = 28 + (number of neutrons). Therefore, you have 32 neutrons. Good Luck!
62030
Protons and neutrons.