Ionization energies first

Table 7.1 Ground configurations and ground states of atoms, listed in increasing order of atomic number Z, and their first ionization energies, E...

The (first) ionization energy is the energy change for the removal of the outermost electron from a gaseous atom to form a +1 ion ... 

What trend is observed in the first ionization energy as you move from lithium down the column I metals On this basis, can you suggest a reason why potassium or cesium might be used in preference to sodium or lithium in photoelectric cells ... 

Experiment shows that a gaseous fluorine atom can acquire an electron to form a stable ion, F (g). We can discuss the energy of formation of this ion in the same way that we treated ionization energies. The first ionization energy of fluorine atom is the energy required to remove an electron from a neutral atom in the gas phase. We shall call this energy Ei. Then the heat of reaction can be written in terms of Ei. 

The first ionization energies of elements 1 to 19 are shown in Table 15-111. The energies to remove successive electrons from gaseous Na, Mg, and A1 atoms are shown in Table 20-IV. 

Make a graph with an energy scale extending on the ordinate from zero to 3000 kcal/mole and with the abscissa marked at equal intervals with the labels Na, Mg, and Al. Now plot and connect with a solid line the first ionization energies, Ei, of these three elements (see Table 20-IV). Hot Et and connect with a dashed line, E with a dotted line, and Et with a solid line. Draw a... 

FIGURE 1.50 Hie first ionization energies of the main-group elements, in kilojoules per mole. In general, low values are found at the lower left of the table and high values are found at the upper right. 

FIGURE 1.51 The periodic variation of the first ionization energies of the elements. 

Self-Test 1.14A Account for the slight decrease in first ionization energy between beryllium and boron. 

The first ionization energy is highest for elements close to helium and is lowest for elements close to cesium. Second ionization energies are higher than first ionization energies (of the same element) and very much higher if the electron is to be removed from a closed shell. Metals are found toward the lower left of the periodic table because these elements have low ionization energies and can readily lose their electrons. 

Arrange the following atoms in order of increasing first ionization energy oxygen, tellurium, selenium. 

Identify the element with the higher first ionization energy in each of the following pairs (a) iron and nickel (b) nickel and copper (c) osmium and platinum (d) nickel and palladium ... 

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