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Why do isotopes on the periodic table have mass numbers that are whole numbers?
Wiki User
∙ 11y ago
This is a great question. Actually before 1961 12C had a different mass than it has today. The mass scale we use is actually relative and before 1961 the mass scale was based on Oxygen so 16O = 16 which was the standard in place since 1906. In the 20's people started to discover oxygen isotopes and the chemists 16O scale was not the same as the physicists 16O scale , so it was decided to settle on Carbon to make both the physicists and chemists happy
Check the related link below for the complete history of what happened
Wiki User
∙ 10y ago
Wiki User
∙ 13y agoAll atomic masses are relative in nature. All are measured and compared by a standard value. C-12 have been taken as standard. Hence all mases after measurement are divided by C-12 mass. This means C-12 will have a whole number mass.
Wiki User
∙ 11y agoOn most periodic tables, only elements that do not occur naturally have mass numbers that are whole numbers. All isotopes of these elements are radioactive, and because the isotopes almost always decay at different rates, there is no stable ratio among the isotopes, as there is with elements that have non-radioactive isotopes. On most periodic tables, such mass numbers are listed within parentheses, and a footnote explains that these are the mass numbers of the longest-lived isotope of the element that is known.
Wiki User
∙ 11y agoAtomic Mass is not represented as whole numbers on the periodic table (unless it is rounded? But that's probably and highly unlikely).
You are probably thinking of the atomic number. That is a whole number because there is a whole number of protons. (You can't have half a proton.)
Wiki User
∙ 9y agoMass number = protons plus neutrons in a particular nucleus. You can't have part of a proton or neutron. Relative atomic mass on the other hand is the average mass of the isotopes in a natural sample (compared to the mass of carbon-12) so can be fractional.
Wiki User
∙ 12y agobecause it is always relative and always decided by calculations from natural abundance.
Anonymous
Wiki User
∙ 10y agobecause on the Periodic Table it has 6 postitve charges and 2 negitive and you get 12 exactly
Wiki User
∙ 11y agobecause it has 6 protons and 6 neutrons
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Do all isotopes have whole number atomic masses?
The short answer is yes. The long answer is that isotopes have different numbers of neutrons than other isotopes of the same element, so when expressing the mass of an isotope, you don't take an average; you just add the number of neutrons and the number of protons. However, that number is not entirely accurate since the mass of a proton and a neutron are very slightly different. So, if you want to be very exact, then no, the mass of an isotope is not a whole number, but it is very, very close.
How do isotopes differ and why is the atomic number of elements not a whole number?
Isotopes differ from each other by having different numbers of neutrons but the same number of protons since they are only the same element if they have the same number of protons. Atomic numbers aren't whole because their mass is based of the mass of hydrogen and amu's (atomic mass units) and due to how elements are formed, minute amounts of mass are lost in order to form the nuclear bonds resulting in not whole numbers.
Why is Tc on the periodic table bracketed and a whole number?
Because Tc (technetium) is unstable and radioactive, therefore hard to weigh, which is why the weight is rounded.
Why are atomic masses of elements usually not whole numbers?
The atomic mass listed in the periodic is found by taking the average of all the different isotopes of a given element found in nature, weighted for their natural abundance.Note that the atomic mass is not the same as the atomic weight. The atomic mass is the weight of one specific isotope of one atom, and is expressed in "atomic mass units" or amu. The atomic weight is expressed in grams per mole (g/mol) and is the weighted average of all the isotopes weighted by their abundance.See the Web Links for more information about atomic mass and atomic weight.
Why are molar masses not a whole number?
Because chlorine (like almost every other element) exists as several isotopes. The molar mass reflects the combined weight and proportion of each of those isotopes.
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
Why the mass numbers on the periodic table of elements are rarely whole numbers?
Elements also possess isotopes. So their average atomic mass is rarely whole number.
What is an element's atomic mass not listed as a whole number on the periodic table?
Few elements have isotopes. their atomic mass is not a whole number.
Why is the atomic mass of sulfur listed on the periodic table not a whole number?
The atomic mass given on the periodic table is a weighted average of all the isotopes, weighted by abundance of each isotope
Why don't the elements on the periodic table have a whole number as their atomic weight?
Elements exist as isotopes in nature. So their atomic weight is not a whole number.
Why don27t elements in the periodic table have whole numbers for their atomic masses?
Because the masses of protons, neutrons and electrons are not whole numbers.
What is the isotope number used for on the periodic table?
There is not an isotope number on the Periodic Table of Elements. There is an atomic number (# of protons) and the average atomic mass. The average atomic mass is the weighted average of all the naturally occurring isotopes for each element. This number is not a whole number, because it is an average of all the isotopes for a particular element.
What number is the whole number found in the periodic table?
There are two numbers that are included in every element's block on every periodic table. The whole number, which can range from 1 - 118 is the atomic number of that element. The atomic number is the number of protons in the nuclei of the atoms of that element. The second number is the atomic weight and is never a whole number, except for the artificially prepared elements, and then it is a whole number written inside parentheses.There may be other numbers listed as well, depending on the periodic table. All periodic tables have a key as to what everything inside each block represents.
Why the atomic mass numbers listed for elements on the Periodic Table are not whole numbers.?
Why are atomic masses of elements not generally whole numbers? The atomic masses listed on the periodic table are a weighted AVERAGE of an element'sisotopes. ... An element's atomic number is the number of protons in its nucleus. Number of protons specifies atom type.
Why is the atomc mass not a whole number?
Atomic mass is the average mass of all the isotopes of an element. This average is depends in part on the relative abundances of these isotopes, which are not whole numbers. Additionally, the masses of protons and neutrons are not exactly 1 AMU. The mass of electrons is also a factor, but their contribution is extremely small.
Why are atomic massed in the periodic table not whole numbers?
Most elements have something called 'Isotopes' which have the same Proton and Electron, but a different Neutron number. So as well as regular C-12, you can get C-14. The atomic mass in the periodic table takes this into account, and the figure it shows is an average, depending on how abundant each isotope is in a typical sample of that element.
Why is the atomic weight of bromine listed on the periodic table not a whole number?
Like almost all of the other elements bromine is a mixture of so-called isotopes. All of these isotopes are bromine and have almost identical chemical properties. They all have the same number of protons in the nuclei of their atoms. However, the numbers of neutrons in their nuclei vary. The atoms of some isotopes of bromine are a little heavier than the atoms of other isotopes. The atomic weight of bromine is the average weight of all of the isotopes of bromine, so it cannot be a whole number.
