The element with an atomic number of 16 is sulfur (S). It belongs to Group 16, which is also known as the oxygen group or chalcogens. Sulfur is located in Period 3 of the periodic table.
The element with an atomic number of 26 is iron (Fe). It belongs to Group 8, which is also known as the iron group or transition metals. Iron is located in Period 4 of the periodic table.
The valency of an element represents the number of bonds an atom of that element can form with other atoms. It is often determined by the number of valence electrons an atom possesses.
For sulfur (atomic number 16), its valency can vary. Sulfur typically has a valency of -2 because it tends to gain two electrons to achieve a stable octet configuration. However, sulfur can also exhibit a valency of +4 or +6 in certain compounds.
For iron (atomic number 26), its valency can also vary. Iron commonly exhibits a valency of +2 or +3, where it loses two or three electrons, respectively, to achieve a stable configuration. Iron can also display other valencies, such as +4 or +6, in certain compounds, although these are less common.
It's important to note that valencies can vary depending on the specific chemical environment and the types of compounds in which the elements are involved.