Energy levels orbitals

An electronic transition involves the raising of an electron to a higher energy level orbital as energy is absorbed. 

Bohr s realization that the atom s energy is quantized—that electrons are restricted to specific energy levels (orbits)— was an astounding achievement. As you have seen, this model successfully predicted the coloured lines in the visible-light portion of hydrogen s emission spectrum. It also successfully predicted other lines, shown in Figure 3.11, that earlier chemists had discovered in the ultraviolet and infrared portions of hydrogen s emission spectrum. 

First, the orbital or quantum theory of matter assumes that the electron is not a particle, as we normally think of particles. Orbital theory considers the electron as a three-dimensional wave that can exist at several energy levels (orbitals), but not at the same time. 

In our discussion of absorption spectroscopy, we noted that the interaction of photons with molecules resulted in the promotion of valence electrons from ground state orbitals to higher energy level orbitals. The molecules were said to be in an excited state. 

The lowest energy level orbital has no nodes the number of nodes increases by one in going from one level to the next higher level. The highest level has a node between each adjacent pair. Nodes must always be symmetrically located with respect to the central mirror plane. 

TABLE 2.2 ENERGY LEVELS, ORBITALS, AND ELECTRONS IN ATOMS ... 

An electron of an atom can be identified using a shorthand notation called electron configuration. This gives the energy level, orbital type and number of electrons present. 

Location Nucleus Nucleus Principal energy levels— orbiting around the nucleus... 

Figure 17 shows the present-day model of the atom, which takes into account both the particle and wave properties of electrons. According to this model, electrons are located in orbitals, regions around a nucleus that correspond to specific energy levels. Orbitals are regions where electrons are likely to be found. Orbitals are sometimes called electron clouds because they do not have sharp boundaries. When an orbital is drawn, it shows where electrons are most likely to be. Because electrons can be in other places, the orbital has a fuzzy boundary like a cloud. 

C is correct. The atom must absorb energy in order for one of its electrons to move to a higher energy level orbital. 

In a similar fashion, five possible d orbitals and seven possible/orbitals exist. The d orbitals exist only in n = 3 and higher principal energy levels /orbitals exist only in M = 4 and higher principal energy levels. Because of their complexity, we will not consider the shapes of d and / orbitals. 

Figure 7.10A shows how Bohr s model accounts for the three line spectra of hydrogen. When a sample of gaseous H atoms is excited, different atoms absorb different quantities of energy. Each atom has one electron, but so many atoms are present that all the energy levels (orbits) are populated by electrons. When the electrons drop from outer orbits to the n = 3 orbit (second excited state), the emitted photons create the infrared series of lines. The visible series arises when electrons drop to the n = 2 orbit (first excited state). Figure 7.1 OB shows that the ultraviolet series arises when electrons drop to the n = 1 orbit (ground state).

Subshells Different energy levels (orbitals) within a given shell... 

To explain the existence of line spectra, Bohr proposed that an electron moves in fixed orbits. It moves from one orbit to another when the atom absorbs or emits a photon whose energy equals the difference in energy levels (orbits). 

I The lowest energy levels (orbits) are those closest to the nucleus. 

II An electron transition from n = 2 energy level (orbit) to an n = 3 energy level (orbit) emits a photon of definite energy. 

III An electron can remain in a particular energy level (orbit) provided it emits radiation of constant frequency,... 

Relative to a random distribution of electrons, the lower energy level orbitals stabilize the system by 4 Dq units per electron, whereas the higher energy orbitals represent a destabilization of 6 Dq units. Thus the crystal... 

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