in case of some elements which has isotopes the atomic masses are different so the average is taken out which may come in decimals.
The atomic number refers to the number of protons in the atom. Since the proton cannot be an in-between number, the atomic number will have to be a whole number. On the other hand, the atomic mass does not have to be a whole number because it is the mass of an atom and is roughly equivalent to the number of protons plus the average number of neutrons in that particular element.
It's because of electrons, they have a relative mass of 1/1836
The atomic mass of an element is measured not in the mass of the atom, but in the number of grams per mole.
The atomic number of an element is the number of protons in the nucleus of each atom of the element. Mass number is a property of a particular isotope of the element rather than of the element itself: The mass number is the sum of the numbers of protons and neutrons in the nucleus of each atom of the isotope.
It's the electrons that throw it off.
Mass Number
Take the Atomic Mass and round it to the nearest whole number. Then subtract this number and the atomic number of that element.
the atomic mass is the number of protons and neutrons in an atom of an element and the atomic number is the number of protons of an atom of an element.
The atomic number is the number of protons in an atom. This number is fixed and determines what element that atom is. The Atomic Mass is the mass of an atom and is roughly equivalent to the number of protons plus the average number of neutrons that atoms of that particular element.
Usually they are measuring just the necleus of the atom since it would be a whole number. This is called finding the Mass number. The atomic weight is the whole atom together, which is a whole lot of decimals. So they take the atomic weight and round it to a whole number for the mass number. For example, Boron (an element on the table) has an atomic weight of 10.811. But scientists round the number upward to 11 to be the Mass number.
Usually they are measuring just the necleus of the atom since it would be a whole number. This is called finding the Mass number. The atomic weight is the whole atom together, which is a whole lot of decimals. So they take the atomic weight and round it to a whole number for the mass number. For example, Boron (an element on the table) has an atomic weight of 10.811. But scientists round the number upward to 11 to be the Mass number.
The atomic number is the number of protons in an atom. This number is fixed and determines what element that atom is. The atomic mass is the mass of an atom and is roughly equivalent to the number of protons plus the average number of neutrons that atoms of that particular element.