Fluorine energy levels

Since, in fhe excifed sfafe, fhe fluorine atoms may be above or below fhe plane of fhe benzene ring fhe potential function for Vu is W-shaped, like fhaf in Figure 6.4f(b). Fitting the observed vibrational energy levels to the potential function in Equation (6.93) gives fhe heighf of fhe barrier to planarify as 78 cm. ... 

This idea is readily extended to simple molecules of compounds formed by nonmetal atoms. An example is the HF molecule. You will recall that a fluorine atom has the electron configuration ls22s22p5. ft has seven electrons in its outermost principal energy level (n = 2). These are referred to as valence electrons, in contrast to the core electrons filling the principal level, n = 1. If the valence electrons are shown as dots around the symbol of the element, the fluorine atom can be represented as... 

We see that the neutral fluorine atom has seven valence electrons that is, seven electrons occupy the outermost partially filled cluster of energy levels. This cluster of energy levels, the valence orbitals, contains one electron less than its capacity permits. Fluorine, then, has the capacity for sharing one electron with some other atom which has similar capacity. If, for example, another fluorine atom approaches, they might share... 

C08-0009. Determine the energy level diagram and shorthand notation for the electron configuration of the fluorine atom. 

Heats of formation for a complete set of Group VILA fluorides are unavailable, but a set of xenon fluoride cations, isoelectronic with iodine fluorides, exhibits the alternating pattern expected for odd- and even-electron molecules. The original energy-level diagram for stepwise fluorine dissociation is shown in Fig. 5. The tabulated values were derived from the ionization energies of XeF and the threshold values for XeFJ — XeF, - + F, where n is even (27), together with heats of formation obtained by reaction calorimetry (137). 

This is a simple example of a heteronuclear diatomic molecule which is found in a stable molecular substance. We must first choose the basis set. The only AOs that need to be seriously considered are the hydrogen Is, fluorine 2s and fluorine 2p, written for brevity as ls(H), 2s(F) and 2p(F). The fluorine Is orbital lies very low in energy (700 eV lower than 2p) and is so compact that its overlap with orbitals on other atoms is quite negligible. The fluorine 2p level lies somewhat lower than ls(H), as indicated by the higher ionisation potential and electronegativity of F. Interaction between 2p(F) and 2s(H) is very small and can be neglected for all practical purposes. One is tempted to discard 2s(F), which lies more than 20 eV below 2p(F) the 2s-2p separation increases... 

Atomic orbital energy level diagrams. To simplify these diagrams, the orbitals are shown at the same energies for different atoms. Actually, the energy of an orbital decreases as the number of protons in the atom increases.Thus the Ip orbitals of fluorine are lower in energy than the Ip orbitals of oxygen. 

As you can see in Figure 2.9C, Period 2 elements have two occupied energy levels. The second energy level is full when eight electrons occupy it. Neon, with a total of ten electrons, has its first and second energy levels filled. Notice how the second energy level fills with electrons as you move across the period from lithium to fluorine. 

More is known about the energy-level dispositions of the excited electronic states of fluorinated benzenes. From the early spectroscopic [68-70] and photophysical... 

The energy level diagrams show one unpaired electron in a fluorine atom, two in an oxygen atom, and one in a boron atom. 

---