Oxygen, atomic elemental halogen

Octet rule (Section 1.3) When forming compounds, atoms gain, lose, or share electrons so that the number of their valence electrons is the same as that of the nearest noble gas. For the elements carbon, nitrogen, oxygen, and the halogens, this number is 8. 

Some elements—particularly the halogens—form more than two kinds of oxoanions. The name of the oxoanion with the smallest number of oxygen atoms is formed by adding the prefix hypo- to the -ite form of the name, as in the hypochlorite ion, CIO-. The oxoanion with the most oxygen atoms is named with the prefix per- added to the -ate form of the name. An example is the perchlorate ion, C104-. The rules for naming polyatomic ions are summarized in Appendix 3A and common examples are listed in Table D.l. 

Fluorine does not form an oxoacid the element is more electronegative than oxygen. In the chlorine, bromine and iodine compounds the halogen atom is positive in relation to the oxygen atoms, as indicated by the <5 s ... 

For nonmetals there is no single rule. Carbon, for example, exists as an extensive three-dimensional network of atoms, and so we use its empirical formula (C) to represent elemental carbon in chemical eqnations. Bnt hydrogen, nitrogen, oxygen, and the halogens exist as diatomic molecules, and so we use their molecular formulas (H2, N2, O2, F2, CI2, Br2,12) in equations. The stable form of phosphorus is molecular (P4), and so we use P4. For sulfur chemists often nse the empirical formula (S) in chemical equations, rather than Sg which is the stable form. Thus, instead of writing the equation for the combnstion of sulfur as... 

A second reason for the vast number of organic compounds is that carbon atoms can form stable bonds with other elements. Several families of organic compounds (alcohols, aldehydes, ketones, esters, and ethers) contain oxygen atoms bonded to carbon. Others contain nitrogen, sulfur, or halogens. The presence of these elements confers a wide variety of new chemical and physical properties on an organic compound. 

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