The family member atomic massive of sodium is no 23amu (amu = atomic mass unit), the is 23 through nounits (as is suggested by words "relative").

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The relative atom mass is the ratioof the typical mass of one atom of one element(given in amu) to 1 amu. because that atoms, theatomic mass one typically uses is essentially thesum of the masses of the protons and neutronswhich consist of the nucleus of the atom; themass of each electron (~1/2000 amu) is negligiblein comparison. Protons and neutrons havesimilar masses, approximately 1 amu each. many sodium atoms have actually 11 protons and also 12 neutrons,giving a total of ~23 amu, and also dividing through 1 amuthen gives 23 for the loved one atomic mass. Notethe use of most in the preceding sentence. Thenumber of proton determines the chemical identityof an element, but the number of neutrons canvary - this are different isotope of one element.

The standard atomic weight takes intoaccount the different relative abundances and also masses that theisotopes by weighting the fixed of isotope by thefrequency of your occurrence. This is why someelements have actually fractional standard weights(e.g. Copper in ~ 63.55).

It"s because sodium atoms each have actually 11 protons,with a fixed of 1, and 12 neutrons, through a mass of1.

periodic table of aspects

Number that Protons/Electrons‎: ‎11Number of power Levels‎: ‎3Number of Neutrons‎: ‎12Atomic Mass‎: ‎22.98977 amu