Periodic table writing electron configuration from

EXAMPLE 9.5 Writing Electron Configurations from the Periodic Table... 

The properties of the elements stem from their electronic configurations, and the properties place them in their locations in the periodic table. In each group, the elements have a characteristic outermost electronic configuration. The existence of the transition and inner transition elements stems from adding electrons to inner shells after outer shells have been started. Because the periodic table reflects the electronic structures of the atoms, it can be used as a memory device when writing electronic configurations. The ability to write and understand such configurations is a very important skill. (Section 4.8)... 

It s not necessary to memorize electron configurations if you can interpret the s, p, d, and f blocks shown in this periodic table. When you write electron configurations, move from left to right through the periods, filling the orbitals that correspond to the s, p, d, and f blocks. 

An important skill that you learned in this chapter is how to use the periodic table to write electron configurations. It should be clear to you now that the organization of the table arises from the electron configurations of the elements. With this added insight, you are ready to learn in Chapter 8 about trends in properties and patterns of behavior of the elements. Knowing electron configurations and periodic trends will help you organize what may seem to be a vast amoimt of information. 

From the periodic table, tin is found to have an atomic number of 50. Thus, a tin atom has 50 electrons. Write out the noble-gas form of tin s electron configuration. 

Hund 22) described the relations between atomic spectroscopy and the Periodic Table. This was a most important pioneer work but made one uncertain extrapolation the almost invariant trivalency made it highly probable that the groundstate of the neutral atoms from lanthanum to lutetium belong to the electron configuration [Xe] 4fcore electrons. We write [68] for the closed shells [Xe] 4fi which are the ground states of Yb+2, Lu+3, Hf+ , . .. 

Let s use the periodic table to write the electron configuration of selenium (Se, element 34). We first locate Se in the table and then move backward from it through the table, from element 34 to 33 to 32 and so forth, until we come to the noble gas that precedes Se. In this case, the noble gas is argon, Ar, element 18. Thus, the noble-gas core for Se is [Ar]. Our next step is to write symbols for the outer electrons. We do this by moving across period 4 from K, the element following Ar, to Se ... 

To write an electron configuration for an element, first find its atomic number from the periodic table—this number equals the number of electrons in the neutral atom. Then use the order of filling from Figure 9.23 or 9.24 to distribute the electrons in the appropriate orbitals. Remember that each orbital can hold a maximum of 2 electrons. Consequently ... 

You can write the electron configuration of an atom with help from the periodic table... 

Step I Locate the element in the periodic table. From its position in the table, identify and write the electron configuration of its highest occupied energy sublevel. (Leave room for writing lower-energy sub-levels to its left.)... 

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