Patients who waited more than 6 months to receive cataract surgery experienced more vision loss, a reduced quality of life and had an increased rate of falls compared with patients who had wait times of less than 6 weeks.
The chalcogens, the oxygen group, is located in column 16 of the periodic table. It contains the elements oxygen, sulfur, selenium, tellurium, polonium, and ununhexium (O, S, Se, Te, Po, and Uuh, respectively). These elements all contain six valence electrons and form 2- ions.
The element fluorine belongs to the group of elements called the halogens. In general, the halogens are the most reactive nonmetals on the periodic table. For nonmetals, the trend of reactivity increases as you go up a group of elements. According to this trend, fluorine then would be the most reactive element in the group of halogens.