The two are counts and so natural numbers. The set of natural numbers is closed under addition.
There are two main reasons. The first is that the masses of protons and neutrons are not 1 unit but slightly greater. The mass of an atom is the mass of a whole number of protons, a whole number of neutrons as well as the same number of electrons as protons. Overall, therefore, the mass should be greater than the number of protons and neutrons (electrons have very little mass). But some of the mass is converted to energy which is used to hold the positively charged nucleus together. As a result the mass of carbon12 is an exact whole number and that is the only element for which that is true.The second, and possibly more relevant reason is that most atoms are found in the form of isotopes which have different numbers of neutrons and so different masses. The atomic mass listed for an element is an average of the masses of all these isotopes, weighted together according to their abundance of earth.
We can find Atomic Mass and mass number in chemical elements. Atomic mass is about weight of the atom. Mass number is about total of neutrons and protons.
It's because of electrons, they have a relative mass of 1/1836
The atomic number is the number of protons.
The atomic mass is the mass of an atom of that element in AMUs. (Atomic Mass Units)The atomic number, however, is equivalent to the number of protons in an atom of that element.The mass number of an atom is the total number of protons and neutrons in the nucleus of an atom. This is therefore always a whole number. The relative atomic mass of an element is the weighted average of the masses of the isotopes relative to 1/12 of the mass of a carbon-12 atom.It is a weighted average as it takes into account the relative abundances of the different isotopes (atoms of the same element but with different numbers of neutrons) of an element. This number is found in the periodic table.For example chlorine has two isotopes, 35Cl and 37Cl, in the approximate ratio of 3 atoms of 35Cl to 1 atom of 37Cl.The number of protons and neutrons in a 35Cl atom must add up to 35, the mass number. The relative atomic mass of chlorine takes into account both isotopes and is therefore 35.5.
This is the mass number.
"Atomic mass" is the sum of the number of protons and neutrons in the nucleus of the atom. All atoms of an element have the same number of protons. For example, all iron atoms have 26 protons. But while most (90%) have 30 neutrons, there are isotopes of iron that have anywhere from 26 to 36 neutrons. So the published "atomic mass" is the weighted average of the combined number of protons and neutrons. That's why the atomic number is always a whole number, but the atomic mass is a decimal.
The Atomic Mass tells you how many Protons and Neutrons are in the atom. It is approximately the sum of the number of protons and neutrons found in the nucleus of an atom. Basically the weight of the neutrons and protons in one atom
Atomic number means number of protons present in an atom. Atomic number= number of protons. mass number = number of neutrons+ number of protons. So if you subtract the number of protons you get neutrons and if you subtract neutrons you get protons. mass number - protons= neutrons Mass number - neutrons = protons.
An atom can't contain only part of a proton, so the number must always be a whole number
mass no. = no. of protons + no. of neutrons
The mass number is a whole number that is equal to the sum of protons and neutrons in an atom. Mass number is represented by the letter (A) orA= Z + N (Z) represent the atomic number or the number of protons in the nucleus.
The mass number is a whole number, but the atomic mass may not be. Mass numbers are the total number of neutrons and protons in an isotope (different from atomic numbers, which are the whole numbers of protons only). These are also whole numbers, and for most lithium, it is 7. The mass number is 6 for lithium-6, which has only 3 neutrons. However, the "atomic mass" of an element is measured in atomic mass units, which are 1/12 of the weight of a carbon-12 atom (6 protons and 6 neutrons). Since neutrons are slightly heavier than protons, and there are more neutrons than protons in lithium-7 (3 protons to 4 neutrons), the atomic mass is slightly more than 7.
All beryllium atoms have 4 protons and 4 electrons. The number of neutrons is characteristic of a particular isotope, not of beryllium as a whole, and may be determined by subtracting 4, the number of protons, from the mass number of the isotope.
It can, and it must.
The atomic weight/mass is the average weight of all the isotopes of that element. Adding the number of protons and neutrons together does equal to the atomic weight, but only if you round the decimal.For example the element sulfur (atomic number 16) has an atomic mass of 32.066. This is not a whole number, but that does not mean that sulfur has 16.066 neutrons. Instead, you would just say that the atomic mass is 32 amu and subtract the number of protons, which is the same as the atomic number, from the atomic mass. Sulfur therefore has 16 neutrons, protons, and electrons.
Look at the atomic mass of the element. Round the atomic mass to the nearest whole number, and subtract the number of protons present in the nucleus (the atomic number). The nucleus of the atom is made of protons and neutrons, so ideally, one can subtract the number of protons or neutrons to get the number of neutrons or protons. So, Lithium would have 4 neutrons, Hydrogen would only have a proton, and Iron has 30 neutrons. Of course, it depends, also, on the isotope of the element, which varies with the number of neutrons. So, carbon-14 would have 8 neutrons and 6 protons, while regular carbon would have 6 protons and 6 neutrons.