for instance, the alkali metals, with their one electron in the s subshell, they all readily give up that electron, and no more than one electron. and all of the halogens, on the other side of the periodic table, with their missing electron in the p subshell, readily accept such an electron. one might ask, why do we concentrate on the outermost electrons and not all the other ones? it's because the outermost electrons are at highest energy. they're furthest away from the nucleus. in them is chemistry. captioning performed by the national captioning institute, inc. captions copyright 1989 educational film center and the university of maryland funding for this program was provided by... additional funding provided by the people of dow, the company that lets you do great things, the 8,000 scientists of the eastman kodak company, the exxon education foundation on behalf of exxon scientists, and... for information on this college telecourse, videocassettes, off-air videotaping, and books based on this series, telephone the annenberg/cpb project at... funding for this program was provided