Neutrons stabilize the nucleus , because they attract each other and protons , which helps offset the electrical repulsion between protons. As a result, as the number of protons increases, an increasing ratio of neutrons to protons is needed to form a stable nucleus.
If there are too many or too few neutrons for a given number of protons, the resulting nucleus is not stable and it undergoes radioactive decay. Unstable isotopes decay through various radioactive decay pathways, most commonly alpha decay, beta decay, or electron capture. Many other rare types of decay, such as spontaneous fission or neutron emission are known. It should be noted that all of these decay pathways may be accompanied by the subsequent emission of gamma radiation.
Pure alpha or beta decays are very rare. The periodic table is a tabular display of the chemical elements organized on the basis of their atomic numbers, electron configurations, and chemical properties. The electron configuration is the distribution of electrons of an atom or molecule or other physical structure in atomic or molecular orbitals. Knowledge of the electron configuration of different atoms is useful in understanding the structure of the periodic table of elements.
Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. The chemical properties of the atom are determined by the number of protons, in fact, by number and arrangement of electrons. It is the Pauli exclusion principle that requires the electrons in an atom to occupy different energy levels instead of them all condensing in the ground state.
This fact has key implications for the building up of the periodic table of elements. The first two columns on the left side of the periodic table are where the s subshells are being occupied. Because of this, the first two rows of the periodic table are labeled the s block. Similarly, the p block are the right-most six columns of the periodic table, the d block is the middle 10 columns of the periodic table, while the f block is the column section that is normally depicted as detached from the main body of the periodic table.
It could be part of the main body, but then the periodic table would be rather long and cumbersome. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. The electron configuration can be visualized as the core electrons, equivalent to the noble gas of the preceding period, and the valence electrons e.
Oxidation states are typically represented by integers which may be positive, zero, or negative. Most elements have more than one possible oxidation state. An element that is not combined with any other different elements has an oxidation state of 0. Oxidation state 0 occurs for all elements — it is simply the element in its elemental form. An atom of an element in a compound will have a positive oxidation state if it has had electrons removed.
Similarly, adding electrons results in a negative oxidation state. We have also distinguish between the possible and common oxidation states of every element. Main Menu. About Protons. About Neutrons. About Electrons and Electron Configuration. Oxidation States Oxidation states are typically represented by integers which may be positive, zero, or negative. How do you calculate atomic mass from isotopic composition? How do atomic mass and atomic weight differ?
How do atomic masses reflect isotope abundances? How do atomic masses vary throughout the periodic table? How much atomic mass is in hydrogen? What atomic mass does ekasilicon have? Why are atomic masses of most of the elements fractional? What is atomic mass? See all questions in Atomic Mass. Impact of this question views around the world. You can reuse this answer Creative Commons License.
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