Energy levels Periodic Table

The different rows of elements are called periods. The period number of an element signifies the highest energy level an electron in that element occupies (in the unexcited state). The number of elements in a period increases as one traverses down the periodic table because as the energy level of the atom increases, the number of energy sub-levels per energy level increases. 

The atoms of elements in a group of the periodic table have the same distribution of electrons in the outermost principal energy level... 

To understand how position in the periodic table relates to the filling of sublevels, consider the metals in the first two groups. Atoms of the Group 1 elements all have one s electron in the outermost principal energy level (Table 6.4). In each Group 2 atom, there are two s electrons in the outermost level. A similar relationship applies to the elements in any group ... 

The decrease in atomic radius moving across the periodic table can be explained in a similar manner. Consider, for example, the third period, where electrons are being added to the third principal energy level. The added electrons should be relatively poor shields for each other because they are all at about the same distance from the nucleus. Only the ten core electrons in inner, filled levels (n = 1, n = 2) are expected to shield the outer electrons from the nucleus. This means that the charge felt by an outer electron, called the effective nuclear charge, should increase steadily with atomic number as we move across the period. As effective nuclear charge increases, the outermost electrons are pulled in more tightly, and atomic radius decreases. 

The hydrogen atom energy levels, together with our two assumptions, have provided a good explanation of some of the properties of the first eleven elements. We shall see that they explain the entire periodic table. 

Now we can see the development of the entire periodic table. The special stabilities of the inert gases are fixed by the large energy gaps in the energy level diagram, Figure 15-11. The number of orbitals in a cluster, multiplied by two because of our double occupancy assumption, fixes the number of electrons needed to reach the inert gas electron population. The numbers at the... 

The colors of fireworks depend on the energies of the atomic orbitals of the various atomic ions, but orbital energy levels have consequences that are much more far-reaching. Orbital energies determine the stabilities of atoms and how atoms react. The structure of the periodic table is based on orbital energy levels. In this chapter we explore the details of orbital energies and relate them to the form and structure of the periodic table. This provides the foundation for interpreting chemical behavior patterns. 

C08-0031. Construct an orbital energy level diagram for all orbitals with < 8 and / < 4. Use the periodic table to help determine the correct order of the energy levels. 

A knowledge of the behavior of d orbitals is essential to understand the differences and trends in reactivity of the transition metals. The width of the d band decreases as the band is filled when going to the right in the periodic table since the molecular orbitals become ever more localized and the overlap decreases. Eventually, as in copper, the d band is completely filled, lying just below the Fermi level, while in zinc it lowers further in energy and becomes a so-called core level, localized on the individual atoms. If we look down through the transition metal series 3d, 4d, and 5d we see that the d band broadens since the orbitals get ever larger and therefore the overlap increases. 

Ans. The n + / rule, the energy level diagram (Fig. 17-7), the periodic table (and some mnemonics given by other texts). 

Appendix 1 also shows how the periodic table of the elements (Appendix 5) can be built up from the known rules for filling up the various electron energy levels. The Bohr model shows that electrons can only occupy orbitals whose energy is fixed (quantized), and that each atom is characterized by a particular set of energy levels. These energy levels differ in detail between atoms of... 

In this section, you saw how the ideas of quantum mechanics led to a new, revolutionary atomic model—the quantum mechanical model of the atom. According to this model, electrons have both matter-like and wave-like properties. Their position and momentum cannot both be determined with certainty, so they must be described in terms of probabilities. An orbital represents a mathematical description of the volume of space in which an electron has a high probability of being found. You learned the first three quantum numbers that describe the size, energy, shape, and orientation of an orbital. In the next section, you will use quantum numbers to describe the total number of electrons in an atom and the energy levels in which they are most likely to be found in their ground state. You will also discover how the ideas of quantum mechanics explain the structure and organization of the periodic table. 

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