Sodium Through Argon
|
The preceding three chapters have been a brief primer of chemistry, with most of the central ideas that will be needed to explain how all atoms behave: electronegativity; ions and atoms; metals and nonmetals; ionic and covalent bonds; gases, liquids, and solids; acids and bases; salts and molecular compounds. The most encouraging single fact of chemistry is that once you understand the properties of these first ten elements, you have a very good idea of how the next eight should react, and the heavier atoms as well. In this chapter we really will not be breaking new ground in looking at the third-shell elements, but merely tying together the ideas in Chapters 3 through 5 and showing how they apply to atoms with more electrons. In Chapter 3 we imagined a process in which we built up heavier and heavier atoms by increasing the charge on the nucleus (by adding more protons) and adding more electrons around the nucleus to keep the atom electrically neutral. The first two electrons went into the inner electron shell, in the elements H and He. |
The next eight electrons were added one at a time to form Li through Ne, while filling a second electron shell. Now if we add more electrons, the next eight can go into a third electron shell to build elements with atomic numbers 11 through 18. The nineteenth electron has to be placed in a fourth shell because the third shell has room for only eight electrons at this point in the periodic table. Thus it is logical to look at elements 11 through 18 as a unit. The next eight electrons were added one at a time to form Li through Ne, while filling a second electron shell. Now if we add more electrons, the next eight can go into a third electron shell to build elements with atomic numbers 11 through 18. The nineteenth electron has to be placed in a fourth shell because the third shell has room for only eight electrons at this point in the periodic table. Thus it is logical to look at elements 11 through 18 as a unit.
|
