Protons energy shells

Carbon, chemical symbol C, has six protons and six electrons. Two electrons fill the inner K energy shell, and there are four electrons in its outer L shell. Since this is exactly halfway to the number eight, which would fill the outer shell, carbon has little tendency to gain or lose electrons. Instead, carbon usually combines by sharing electrons with two, three, or four other atoms. 

All the transition elements have large atomic numbers, the smallest (scandium) having 21 protons. All of them have at least four energy shells holding their electrons. Scientists do not know exactly why, but the transition element atoms often put electrons into a new, outer energy shell when some inner shells are not quite full. All the transition elements have one or two electrons in their outer shells, but from element to element each new electron is added to a shell deep inside the electron cloud. 

Electron capture has the same effect as positron emission. In this process, an electron from an inner energy shell (especially the Is orbital) is captured by the nucleus. The captured electron is used to convert a proton into a neutron. This conversion can be shown thus ... 

Periods are horizontal rows on the table. Each successive element has one additional proton and one additional electron. Each period represents filling a quantum energy level on that series of atoms. Elements at the end of a period have filled electron energy shells and are especially stable. Groups are vertical columns. Members of the same group have similar chemical and physical properties. In the older A/B numbering system, representative ele-... 

These numbers explain the shape of the periodic table. Each element has one more electron (and one more proton and perhaps more neutrons) than the one before. At first the lowest energy shell (n = 1) is filled. There is only one orbital, Is, and we can put one or two electrons in it. There are therefore two elements in this block, H and He. Next we must move to the second shell ( = 2), filling 2s first so we start the top of groups 1 and 2 with Li and Be. These occupy the top of the red stack marked s block because all the elements in this block have one or two electrons in their outermost s orbital and no electrons in the outermost p orbital. Then we can start on the 2p orbitals. There are three of these so we can put in six electrons and get six elements B, C, N, O, F, and Ne. They occupy the top row of the black p block. Most of the elements we need in this book are in those blocks. Some, Na, K, and Mg for example, are in the s block and others, Si, P, and S for example, are in the second row of the p block. 

Protons and neutrons reside in energy shells, just as electrons do. This fact limits the number of protons and neutrons that a nucleus can have and still remain stable. 

Matter is composed of atoms. An atom consists of a nucleus containing protons (Z) and neutrons (N), collectively called nucleons, and electrons rotating around the nucleus. The sum of neutrons and protons (total number of nucleons) is the mass number denoted by A. The properties of neutrons, protons, and electrons are listed in Table 1.1. The number of electrons in an atom is equal to the number of protons (atomic number Z) in the nucleus. The electrons rotate along different energy shells designated as A -shcll, L-shell, M-shell, etc. (Fig. 1.1). Each shell further consists of subshells or orbitals, e.g., the L-shell has s orbital the L-shell has s and p orbitals the M-shell has s, p, and d orbitals, and the A-shell has s, p, d, and / orbitals. Each orbital can accommodate only a limited number of electrons. For example, the s orbital contains up to 2 electrons the p orbital, 6 electrons the d orbital, 10 electrons and the / orbital, 14 electrons. The capacity number of electrons in each orbital adds up to give the maximum number of electrons that each energy shell can hold. Thus, the L-shell contains 2 electrons the L-shell 8 electrons, the M-shell 18 electrons, and so forth. 

He atoms, by the spatial floppiness of the cluster structures and by the contributions from the ZPE energy corrections. It also confirmed our earlier suggestions from the ab initio, MRD-CI calculations [13] that the protonated clusters tend to arrange themselves, at least initially, into definite energy shells with specific magic numbers (e.g. n = 2,6 and 13). 

We also apply the CDW-EIS model to the energy distributions of electrons ejected from argon by 1-MeV protons [41]. For the argon target we have calculated the contributions from various shells which are then added to obtain... 

Atoms consist of electrons and protons in equal numbers and, in all cases except the hydrogen atom, some number of neutrons. Electrons and protons have equal but opposite charges, but greatly different masses. The mass of a proton is 1.67 X 10 24 grams. In atoms that have many electrons, the electrons are not all held with the same energy later we will discuss the shell stmcture of electrons in atoms. At this point, we see that the early experiments in atomic physics have provided a general view of the structures of atoms. 

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