Atomic number defined

Atomic number The number of protons in the atom. The atomic number defines the element. 

Define atomic number. Define elementary substance in terms of atoms. 

The information index on size is the -> total information content on the atom number, defined as ... 

DO NUM = IDNODE, NANGLES, NODES Ifind atom numbers defining angle i = 1, angl(num) j = 1, ang2(num) k = 1, ang3(num)... 

The mass number and charge can vary for a given element, but the atomic number defines the element and is therefore always the same for a given element. Atoms that have the same atomic number but different mass numbers are called isotopes, and atoms that have lost or gained electrons to acquire a charge are called ions. A positive ion is called a cation, and a negative one is called an anion. 

Zi is the atomic number. The chi molecular connectivity indices are obtained by summing )ns of these delta values. Thus the chi index of order zero is defined as follows ... 

The number of protons in an atom defines what element it is. For example carbon atoms have six protons, hydrogen atoms have one, and oxygen atoms have eight. The number of protons in an atom is referred to as the atomic number of that element. The number of protons in an atom also determines the chemical behavior of the element. 

The analysis of steady-state and transient reactor behavior requires the calculation of reaction rates of neutrons with various materials. If the number density of neutrons at a point is n and their characteristic speed is v, a flux effective area of a nucleus as a cross section O, and a target atom number density N, a macroscopic cross section E = Na can be defined, and the reaction rate per unit volume is R = 0S. This relation may be appHed to the processes of neutron scattering, absorption, and fission in balance equations lea ding to predictions of or to the determination of flux distribution. The consumption of nuclear fuels is governed by time-dependent differential equations analogous to those of Bateman for radioactive decay chains. The rate of change in number of atoms N owing to absorption is as follows ... 

In 1913 Niels Bohr proposed a system of rules that defined a specific set of discrete orbits for the electrons of an atom with a given atomic number. These rules required the electrons to exist only in these orbits, so that they did not radiate energy continuously as in classical electromagnetism. This model was extended first by Sommerfeld and then by Goudsmit and Uhlenbeck. In 1925 Heisenberg, and in 1926 Schrn dinger, proposed a matrix or wave mechanics theory that has developed into quantum mechanics, in which all of these properties are included. In this theory the state of the electron is described by a wave function from which the electron s properties can be deduced. 

Formulate the constraining material-balance equations, based on conservation of the total number of atoms of each element in a system comprised of w elements. Let subscript k identify a particular atom, and define Ai as the total number of atomic masses of the /cth element in the feed. Further, let a be the number of atoms of the /cth element present in each molecule of chemical species i. The material balance for element k is then... 

The arrangement of electrons in an atom is described by means of four quantum numbers which determine the spatial distribution, energy, and other properties, see Appendix 1 (p. 1285). The principal quantum number n defines the general energy level or shell to which the electron belongs. Electrons with n = 1.2, 3, 4., are sometimes referred to as K, L, M, N,. .., electrons. The orbital quantum number / defines both the shape of the electron charge distribution and its orbital angular... 

When a molecule is symmetric, it is often convenient to start the numbering with atoms lying on a rotation axis or in a symmetry plane. If there are no real atoms on a rotation axis or in a mirror plane, dummy atoms can be useful for defining the symmetry element. Consider for example the cyclopropenyl system which has symmetry. Without dummy atoms one of the C-C bond lengths will be given in terms of the two other C-C distances and the C-C-C angle, and it will be complicated to force the three C-C bonds to be identical. By introducing two dummy atoms to define the C3 axis, this becomes easy. 

The energy levels of a hydrogen atom are defined by the principal quantum number, n = 1,2, and form a converging series, as shown in Fig. 1.28. 

The state of an electron in a hydrogen atom is defined by the four quantum numbers n, l, and ms as the value ofn increases, the size of the atom increases. 

Heats of atomization belong to the most important characteristics of ground states. Unfortunately, the number of conjugated radicals for which experimental data are available is very limited. A heat of atomization is defined as the enthalpy of the reaction... 

The subscript Z is redundant because each chemical symbol already defines a unique atomic number. The subscripts are... 

The atomic PDF is related to the probability to find a spherical shell around a generic atom (scattering center) in the material - it is defined as G(r) = Anp[p r)-p(, where p r) and po are, respectively, the local and average atomic number densities and r the radial distance. G(r) is the Fourier transform of the total structure factor Sid). ... 

The spatial resolution in quantitative analysis is defined by how large a particle must be to obtain the required analytical accuracy, and this depends upon the spatial distribution of X-ray production in the analysed region. The volume under the incident electron beam which emits characteristic X-rays for analysis is known as the interaction volume. The shape of the interaction volume depends on the energy of the incident electrons and the atomic number of the specimen, it is roughly spherical, as shown in Figure 5.7, with the lateral spread of the electron beam increasing with the depth of penetration. 

Because the velocity is implicitly defined [17] when electric and magnetic fields are used in the geometry shown in figure 5, the rate of energy loss is independent of the mass of the particle and is just proportional to the atomic number squared ... 

Hypervalency can be defined most simply with respect to purely empirical aspects of chemical periodicity. As beginning chemistry students are taught, each chemical family is associated with a column of the periodic table and associated valence atomic number ZAval, such that the empirical valency FAemp is the minimum shift of ZAval to reach the nearest rare gas,... 

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