The Periodic Table. Jedediah Mephistophles Soltmann. Dmitri Mendeleev. Studied the properties of elements and organized the elements by similar properties (families) and by increasing atomic mass. He left blanks for elements he knew had to exist, such as:. Ekaaluminum (gallium).
The Answer is Silicon
What defines a metal?
We’ve used words like: luster, ductility, malleability, & conductivity. Why do metals behave this way?
Metals tend to be larger atoms. Since it is easier to remove an electron from a larger atom, it should make sense then that metals tend to form cations.
Conversely we can say that the larger an atom is (or the lower its first ionization is) the more metallic the atom is.
So if we compared O, S, and Se (all nonmetals) we could say that selenium, being the largest atom, is the most metallic - even though it is a nonmetal.
Nonmetals tend to be smaller atoms. Since it is easier to add an electron to a smaller atom, it should make sense then that nonmetals tend to form anions.
Conversely we can say that the smaller an atom is (or the higher its first ionization is) the more nonmetallic the atom is.
So if we compared Li, Na, and K (all metals) we could say that lithium, being the smallest atom, is the most nonmetallic - even though it is a metal.