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.
Group 0 elements are on the far right of the periodic table with a very stable completely filled shell of outer electrons. 1  You would expect them to be very unreactive non-metals. 2  The Group 0 Noble Gases are colourless nonâmetals with very low melting and boiling points (they are all gases at room temperature).