I am confused, selenium Se, is on the periodic table, but does it combine with other elements on the periodic table? I want to say no because it is a gas. Is that correct.

Selenium (Se) is actually not a gas, but a nonmetal element that is found in the solid state at room temperature. It belongs to the same group as oxygen (Group 16 or Group VI) on the periodic table, which is known as the chalcogens. While selenium itself is not a gas, it can form compounds with other elements.

When considering the chemical properties of an element, it is important to look beyond its physical state. Elements can react and form compounds with other elements, regardless of whether they are solids, liquids, or gases. In the case of selenium, it can combine with a variety of elements to form different compounds such as selenides, oxides, and halides.

For example, selenium can react with metals, such as copper, to form copper selenide (CuSe). It can also react with oxygen to form selenium dioxide (SeO2) or selenium trioxide (SeO3). These compounds have different properties and characteristics compared to pure, elemental selenium.

In summary, while selenium is not a gas, it can indeed combine with other elements on the periodic table to form various compounds.