We will need 14 boxes to contain the electrons needed to fill the seven f orbitals. Look again at Figure 5.8 and note that the 4f sublevel is filled after the 6s sublevel and before the 5d sublevel. The next step is where period 6 differs from period 5. Period 6 starts with elements whose last added electron is in the 6s sublevel. Just as period 4 contains more elements than period 3, period 6 contains more elements than period 5. Boxes for the elements formed by filling the orbitals of these sublevels are arranged as were those in period 4. The boxes for the elements formed by filling the p orbitals are in place under the boxes for elements formed by adding the 3p electrons.īy consulting Figure 5.8, we see that the next sublevels filled are in the order: 5s, 4d, and 5p. The 4p sublevel is filled next, after the 3d sublevel. Ten electrons are needed to fill the five d orbitals, so we start ten columns in this fourth period, placing the columns next to column 2 and between it and column 3. These are the first d electrons added, so we start new columns for the elements formed by their addition. Figure 5.8 shows that the next sublevel to fill is the 3d sublevel. So we must start here a new period, period 4, and put boxes for the elements formed by filling the 4s sublevel in those columns. Figure 5.11 shows that elements whose last added electron goes into an s sublevel are in columns 1 and 2. Notice that the 4s sublevel is filled immediately after the 3p sublevel. Look back now to Figure 5.8, which shows the order in which the sublevels fill. Period 3 also has eight boxes, which would correspond to the electrons needed to fill the 3s and 3p sublevels. Instead of symbols for eight elements, Figure 5.11 shows s in the first two boxes and p in the last six boxes, showing that the 2s and 2p sublevels are being filled as the electron configurations of the elements in these boxes are completed. In Figure 5.11 we show instead the letter s indicating that the last added electron for the elements in these boxes is in the 1s sublevel. In the usual table, these boxes would contain the symbols for hydrogen and helium, the elements in this period. We will use Figure 5.11 and Figureĥ.8 to relate the electron configuration of an element to its position inįIGURE 5.11 The periodic table and the energy level subshells.įIGURE 5.8 The principal energy levels of an atom and the Instead it shows the last sublevels filled in describing the electron configurations Electron Configuration and the Periodicįigure 5.11 again shows the periodic table but without the symbols of the elements. Thus the elements in column 8 are known as the family or group of noble gases.Ī. The elements in a column make up a family of elements. In the middle of the table, have not been numbered.įIGURE 5.10 Periodic table of the elements. The table so that the table will fit into a reasonable space. These two displays are customarily put below Again, in some tables actinium is the first Similarly, theĭisplay labeled "actinides" belongs in period 7 between element 89 (actinium)Īnd element 104 (rutherfordium). Tables, lanthanum is the first member of the lanthanide series. Of elements labeled "lanthanides" and placed below the table belongs in periodĦ between element 57 (lanthanum) and element 72 (hafnium). Rows are called periods and each period is numbered. Seven rows are used to show all of the elements now known. In the table, the elements are placed in rows and columns of Section we will show how the various features of the table relate to the electronĬonfiguration of the different elements and to their position in the table.įirst let us point out those features using the complete periodic table shown We also pointed out that theĭesign of the periodic table separates the metals from the nonmetals. Table was introduced as a list of the elements.
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