1
Mixtures that don't have a uniform composition
2
Pure substances are often elements or _________
3
Mixtures that have a uniform composition
4
Changes such as melting are called _____ changes
5
Energy such as solar, biomass, etc.
6
Changes such as combustion are called ______ changes
7
Materials that are obtained by modification of natural resources by humans are called ________ materials
8
Materials that can be found on Earth and are not modified by mankind yet are called _____ materials
