The two main elements that make up the compounds in glass are silicon (Si) and oxygen (O).

Here's why:

* Silicon dioxide (SiO₂) is the primary component of most glass. It forms a strong, rigid structure that gives glass its characteristic properties.

* Other elements are added to SiO₂ to modify the properties of glass. For example, sodium (Na) and calcium (Ca) are added to make the glass easier to melt and form, while lead (Pb) can be added to create lead crystal, which is known for its sparkle.

So, while silicon and oxygen are the fundamental elements, there are often additional elements that create different types of glass.