A little more than three-quarters of naturally occurring elements exist as a mixture of isotopes, and the average isotopic mass of an isotopic mixture for an element in a defined environment on Earth, determines the element's standard atomic weight. Since protons and neutrons have approximately the same mass, and the mass defect of nucleon binding is always small compared to the nucleon mass, the atomic mass of any atom, when expressed in unified atomic mass units is roughly equal to the whole number A.Ītoms having the same atomic number Z but different neutron number N, and hence different atomic masses, are known as isotopes. The number of neutrons, N, is known as the neutron number of the atom thus, A = Z + N. The atomic number, Z, should not be confused with the mass number, A, which is the number of nucleons, the total number of protons and neutrons in the nucleus of an atom. In an atom of neutral charge, the atomic number is also equal to the number of electrons.

The atomic number uniquely identifies a chemical element. Atomic structure definition, the structure of an atom, theoretically consisting of a positively charged nucleus surrounded and neutralized by negatively charged electrons revolving in orbits at varying distances from the nucleus, the constitution of the nucleus and the arrangement of the electrons differing with various chemical elements.

However, electrons are so small that they are. It is conventionally represented by the symbol Z. Atomic mass is the total mass of particles of matter in an atom, i.e., the masses of protons, neutrons, and electrons in an atom added together. In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. The amount of neutrons in any given atom by subtracting the atomic number from the atomic mass.Freebase (0.00 / 0 votes) Rate this definition: The number of an isotope directly correlates to the atomic mass of an element. This is the defining characteristic of an element.

However, we can add two more neutrons and carbon-12 is now carbon-14, a less stable isotope of carbon. The atomic number of an atom identifies the number of protons in the atom. As an example, carbon-12 is the most stable isotope for a carbon atom. Adding or removing neutrons within an atom changes its isotope. Electrons are the foundation for determining how compounds are formed amongst atoms. Non-metals tend to gain electrons, forming a negative charge. Metals tend to lose electrons, which creates a positive charge. Adding more electrons will give the atom a negative charge and removing electrons will give the atom a positive charge. The same cannot be applied to when another neutron or another electron is added. Once another proton is added, it is no longer the same element. The atomic number of the periodic table directly corresponds to the number of protons which is in the atom. relative atomic mass (also called atomic weight symbol: A r), which is the ratio of the average mass per atom of an element from a given sample to 1/12 the mass of a carbon-12 atom.mass number (symbol: A), which is the sum of the number of protons and number of neutrons in the nucleus of an atom We found 9 dictionaries with English definitions that include the word atomic number 50: Click on the first link on a line below to go directly to a page where 'atomic number 50' is defined.atomic mass (symbol: m a), which is the mass of a single atom, commonly expressed in unified atomic mass units.The elements of the periodic table are listed in order of increasing atomic number. In a neutral atom, the atomic number is equal to the number of electrons orbiting the nucleus. The atomic number of an atom identifies which element it is. The atomic number (symbol: Z) of an atom is the number of protons in the nucleus of the atom.

Atomic number definition