Final answer:
The statement that hydrogen atoms are often the central atom of a Lewis structure is false. The central atom is typically the least electronegative element that is capable of connecting to multiple atoms, unlike hydrogen, which tends to be a terminal atom.
Step-by-step explanation:
The statement "Hydrogen atoms are often the central atom of a Lewis structure" is FALSE. When constructing a Lewis structure, which is a graphical representation of the valence electrons of an atom or a molecule, it's crucial to identify the central atom correctly. The central atom is generally chosen based on its electronegativity. Since hydrogen has only one valence electron, it does not have the capacity to connect to multiple other atoms to form a central core. Rather, the central atom is usually the one that is the least electronegative, except for hydrogen and the halogens, which are more electronegative and tend to be terminal rather than central in the molecule.
For example, in a compound such as carbon tetrachloride (CCl4), carbon is the least electronegative element compared to chlorine, and thus carbon is the central atom. Similarly, in carbonate ion (CO3²⁻), carbon is the central atom with oxygen atoms surrounding it. Molecules like water (H2O), ammonia (NH3), and methane (CH4) follow the same principle where hydrogen atoms are never found in the central position. This is because hydrogen can only make one bond due to having only one valence electron.
When creating Lewis structures, it's also important to remember that the central atom often ends up with additional electrons after the valence shells of the outer (terminal) atoms have been filled. These excess electrons are utilized to complete the octet of the central atom. In substances such as phosphorus oxychloride (POCl3), sulfur dioxide (SO2), and perchlorate ion (ClO4⁻), the central atoms are phosphorus, sulfur, and chlorine, respectively, each less electronegative than hydrogen and capable of forming multiple bonds.