Which is made up of only one type of atom? a compound an element a solution a homogeneous mixture

An element is just another way of saying an atom. They are EXTREMELY similar, except they are not the same... To put it simply "Imagine going to an ice cream store. Let's say they have 30 different flavors of ice cream. Those are elements, the things I have available from which to build my dessert. The smallest amount of ice cream the store will sell to me is a scoop. This is an atom." (credits: https://education.jlab.org/qa/atoms_and_elements.html)

law of conservation of matter

a electronegativity decreases beacuse the size of nucleus is bigger.