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 elements of Group 17 the halogens are found on the right side of the periodic table between groups 13-16 and group 18. The halogen group periodic table is shown below. The first member of this family is fluorine which is the most reactive and the most electronegative element known.