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The mass number is the combined number of protons and neutrons in the nucleus of the particular element you are looking at.

NOTE: (don't be confused by the Periodic Table) Different elements have isotopes with varying mass numbers, so the mass number displayed on a periodic table is the ratio of those isotopic mass numbers in any given sample of the element your examining. This ratio is often confused with with the mass number of the element when it is displayed on periodic tables, it is actually the relative Atomic Mass. You can tell if a number is the mass number or a relative atomic mass by whether or not it is a whole number if it is then it's a mass number if it has decimal places out beside it then you're looking at relative atomic mass.

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15y ago
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11y ago

mass number = number of protons + number of neutrons

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13y ago

The mass of a specific isotope.

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Q: What does the mass number on the periodic table mean?
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Related questions

What Does Ga Mean on A Periodic Table?

Ga on the periodic table means Gallium [MORE INFO...] Mass number is 70 Atomic number is 31 =p


What does 33 mean in the periodic table?

could be either the atomic number or the mass number of the element, depending on what you are referring to.


What mass is listed in the periodic table?

Atomic weight, which is the mean relative mass and is dimensionless.


What does k mean periodic table?

K on the periodic table is Potassium. It has a mass of 39.0983 amu and its atomic number is 19.K is the symbol for potassium.


Why elements don't have whole numbers?

do you mean the why is the average atomic mass not a whole number? because if that is your question, then the answer is that each element has multipal isotopes and the mass you see on the periodic table is the average of all the isotopes together. So there has to be a decimal on the periodic table of elements


How was mass number arranged in the periodic table?

Strictly, atomic mass is not organised on the periodic table - the periodic table is arranged according to the atomic number (i.e. the number of protons in the nucleus) of the elements.However, as the number of neutrons that are required in the nucleus increases as the number of protons increases, it means that with increasing atomic number you generally get a increase in atomic mass as you go further up the periodic table.BUT, there are exceptions - for complex reasons relating to nuclear stability, the average atomic mass of cobalt (atomic number 27) is actually greater than that of nickel (atomic number 28), and the atomic mass of plutonium (atomic number 94) is greater than that of Americium (atomic number 95).


What does Th mean in the periodic table?

Th is element number 90 on the periodic table It is thorium, it is in the Actinides, and it is radioactive


What does the number on top of the symbol mean in the periodic table?

It is the Atomic Number.


What is the number of potassium?

Potassium, K, is in Group 1 of the periodic table


What does row numbers mean?

The number of period in periodic table.


What does the period number on periodic table mean?

The group number is an identifier used to describe the column of the standard Periodic Table in which the element appears.


The atomic number of carbon is 6what do you mean by it?

It is number six in the Periodic Table.