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.
Nitrogen is classified as an element in the 'Non-Metals' section which can be located in groups 14,15 and 16 of the Periodic Table. Non-metallic elements exist, at room temperature, in two of the three states of matter: gases (Oxygen, Hydrogen & Nitrogen) and solids (Carbon, Phosphorus, Sulfur and Selenium).