Condensed electron configurations

The condensed electron configuration for a nitrogen atom, for example, is [He]2s 2p. The notation [He] is used to represent Is. For a sodium atom [Z = 11), the condensed electron configuration is [Ne]3s. Here, [Ne] represents, ls 2s 2p . Be aware that condensed electron configurations are simply convenient short forms. Thus, [Ne]3s does not mean that a sodium atom is the same as a neon atom plus one electron. Sodium and neon are different elements because the nuclei of their atoms are completely different. 

Write condensed electron configurations for atoms of these same elements. 

Make a rough sketch of the periodic table for elements 1 through 18, including the following information group number, period number, atomic number, atomic symbol, and condensed electron configuration. 

You do not have a periodic table. You are told that the condensed electron configuration for strontium is [Kr]5s. Identify the group number, period number, and orbital block in which strontium appears on the periodic table. Show your reasoning. 

For each of the elements below, use the aufbau principle to write the full and condensed electron configurations and draw partial orbital diagrams for the valence electrons of their atoms. You may consult the periodic table in Appendix C, or any other periodic table that omits electron configurations. 

O Use the aufbau principle to write complete and condensed electron configurations for the most common ions for the elements listed below, and explain the significance of any patterns you observe in their electronic structures. 

Because reactions occur primarily with the valance electrons (electrons added since the last noble gas), the electron configurations can be rewritten as a condensed electron configuration identifying the last noble gas in brackets and listing only the valence electrons (see Table 10.1). 

The electronic configuration of calcium, 20Ca, can be written as lsz2sz2p63sz3p64sz or as [Ar]4sz. Condensed electronic configuration will be extensively used in the discussion of valence electrons later in this chapter. 

There are six ground state electronic configurations for main-group elements given below. Identify the valence electrons in each and then group them in pairs that would be expected to have similar chemical properties. Hint Rewrite each as a condensed electronic configuration. 

Answer Similar valence electron arrangements predict similar chemical properties (a) and (c) are both ns1 (b) and (e) are both ns2np3 (d) and (f) are both ns2. Rewriting each as a condensed electronic configuration lets you focus on the valence electrons. 

Atomic Number Element Partial Orbital Diagram (35 and 3p Sublevels Only) Full Electron Configuration Condensed Electron Configuration... 

One of the central points in all chemistry is that similar outer electron configurations correlate with similar chemical behavior. Figure 8.4 shows the condensed electron configurations of the first 18 elements. Note the similarities within each group. Here are some examples from just three groups ... 

In Group IA(1), lithium and sodium have the condensed electron configuration [noble gas] ns (where n is the quantum number of the outermost energy level), as do all the other alkali metals (K, Rb, Cs, Fr). All are highly reactive metals that form ionic compounds with nonmetals with formulas such as MCI, M2O, and M2S (where M represents the alkali metal), and all react vigorously with water to displace H2. 

In Group 7A(17), fluorine and chlorine have the condensed electron configuration [noble gas] ns np, as do the other halogens (Br, I, At). Little is known about rare, radioactive astatine (At), but all the others are reactive nonmetals that occur as diatomic molecules, X2 (where X represents the halogen). All form ionic compounds with metals (KX, MgX2), covalent compounds with hydrogen (HX) that yield acidic solutions in water, and covalent compounds with carbon (CX4). 

FOLLOW-UP PROBLEM 8.2 Without referring to Table 8.3 or Figure 8.5, give full and condensed electron configurations, partial orbital diagrams showing valence electrons, and the number of inner electrons for the following elements ... 

SAMPLE PROBLEM 8.6 Writing Electron Configurations of Main-Group Ions Problem Using condensed electron configurations, write reactions for the formation of the common ions of the following elements ... 

Problem Use condensed electron configurations to write the reaction for the formation of each transition metal ion, and predict whether the ion is paramagnetic ... 

Plan We first write the condensed electron configuration of the atom, noting the irregularity for Cr in (b). Then we remove electrons, beginning with ns electrons, to attain the ion charge. If unpaired electrons are present, the ion is paramagnetic. 

FOLLOW-UP PROBLEM 9.1 Use condensed electron configurations and Lewis symbols to depict the formation of Mg mula of the ionic compound. 

Use condensed electron configurations and Lewis electron-dot symbols to depict the monatomic ions formed from each of the following atoms, and predict the formula of the compound the ions produce ... 

Use condensed electron configurations to predict the relative hardnesses and melting points of rubidium (Z = 37), vanadium (Z = 23), and cadmium (Z = 48). 

We can generalize what we have just done for the electron configuration of sodium. In writing the condensed electron configuration of an element, the electron configuration of the nearest noble-gas element of lower atomic number is represented by its chemical symbol in brackets. For lithium, for example, we write... 

We refer to the electrons represented by the bracketed symbol as the noble-gas core of the atom. More usually, these inner-shell electrons are referred to as the core electrons. The electrons given after the noble-gas core are called the outer-shell elearons. The outer-shell electrons include the electrons involved in chemical bonding, which are called the valence electrons. For the elements with atomic number of 30 or less, all of the outer-shell electrons are valence electrons. By comparing the condensed electron configurations of lithium and sodium, we can appreciate why these two elements are so... 

In writing the electron configurations of the transition elements, we fill orbitals in accordance with Hund s rule—we add them to the 3d orbitals singly until all five orbitals have one electron each and then place additional electrons in the 3d orbitals with spin pairing until the shell is completely filled. The condensed electron configurations and the corresponding orbital diagram representations of two transition elements are as follows ... 

Use the periodic table to write the condensed electron configuration for (a) Co (element 27), (b) Te (element 52). 

The valence electrons are the ones in the outermost occupied shell, the 2s and 2p electrons. The Is electrons constitute the core electrons, which we represent as [He] when we write the condensed electron configuration, [He]2s 2p . 

Use the periodic table to write condensed electron configurations and determine the number of unpaired electrons in an atom. (Section 6.9)... 

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