![]() One schematic model of lithum ion (Li+)Įquating the centrifugal force to the Coulomb force, we have 1.) in which two electrons of the lithium ion are on the opposite sides of the nucleus and moving on the same circular orbit.įig. Lithium ion (Li+) has two electrons and one nucleus (3e+).įirst, suppose we have one model (Fig. So the ground state energy of the lithium ion (Li+) is -75.64 - 122.45 = -198.09 eV. The ionization energies of the lithium is 5.39 eV (1st), 75.64 eV (2nd), and 122.45 eV (3rd), respectively. Naturally occurring lithium is composed of two stable isotopes, Li6 and Li7, the latter being the more abundant (92.5%). because of this, it is a good conductor of both heat and electricity, and used for the lithium (ion) batteries. Lithium has a single valence electron ( its configuration, 1S × 2, 2S × 1 ) that is easily given up to form a cation. It is the lightest metal, and highly reactive and flammable (though more stable than the other alkali metals). Lithium belongs to the alkali metal group of chemical elements, and has the atomic number 3. So next, we try Lithium atom (Li) and Lithium ion (Li+) by Bohr's theory. Our new Bohr model has suceeded in calculating the Helium ionization energy more correctly than the quantum mechanical variational methods as shown in the Top page. Top page (correct Bohr model including the two-electron atoms). As shown in Figure 1 of the Orbitals page, the 2 s electron cloud is bigger than 1 s even in the hydrogen atom with a nuclear charge of only +1.Bohr's Lithium(ion) Li(+) New Bohr model Lithium (Li) The first reason is that the principal quantum number n has increased from 1 to 2. There are two reasons why this 2 s cloud is so large. In sharp contrast to this compact inner orbital is the very large and very diffuse cloud of the outer 2 s electron. The superscripts 2 and 1 indicate that there are two electrons in the 1 s orbital and one electron in the 2 s orbital, respectively.Īs in the case of helium, the increase in nuclear charge to +3 produces a corresponding reduction in the size of the lithium 1 s orbital. ![]() A convenient shorthand form for indicating this electron configuration is The Pauli principle prevents more than two electrons from occupying this orbital, and so the third (red) electron must occupy the next higher orbital in energy, namely, the 2s orbital. As in the previous atom, two electrons (blue and green) occupy the 1 s orbital. In the dot density image below, the three electrons of the lithium atom are color-coded blue, green, and red. This effect is offset, but to a lesser extent, by the mutual repulsion of the two electron clouds. This pulls both the green and the blue electron clouds in more tightly. This contraction is caused by the increase in the charge on the nucleus from +1 in the hydrogen atom to +2 in the helium atom. The Pauli principle implies that if two electrons have parallel spins, they must occupy different orbitals.Īn obvious feature of the helium atom shown below is that it is somewhat smaller than the hydrogen atom drawn to the same scale above. Two electrons spinning in the same direction are said to have their spins parallel and are indicated by. Two such electrons are said to be spin paired and are often represented by arrows pointing in different directions, i.e., by the symbol. According to the Pauli exclusion principle, if two electrons occupy the same orbital, they must have opposite spins. Two orientations (clockwise and counterclockwise, referred to as spin up or spin down) are possible for this spin. Electrons can not only move about from place to place, but they can also rotate or spin about themselves. This restriction is connected with a property of the electrons not yet discussed, namely, their spin. ![]() It turns out that 2 is the maximum number of electrons any orbital can hold. Note that both electrons occupy the same orbital, namely, a 1 s orbital. ![]() One electron is color coded in blue, and the other in green. Dot-density diagrams for both these electrons are shown below. ![]() The first element in the periodic table with more than one electron is helium, which has two electrons. In these diagrams, each electron wave is displayed with a different color and you can toggle the view of each electron wave on and off using the buttons below the dot density diagrams. Thus, more dots indicates more electron density 'cloud' in that region. The images found here depict electron wave density by number of dots. With some familiarity with the properties of single electrons, such as the single electron around the hydrogen nucleus above, we can discuss atoms containing more than one electron. ![]()
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