You can see below an interactive image that describes a list of elements that make up the different parts of the cell phone.
In your contribution, you could (these are just ideas)
talk about one or two of those elements (physical and chemical properties, why are they uses, etc..)
share where some of the elements are geographically found, how they are mined, price, etc..
talk about the social, economical and environmental issues around some of the elements.
health concern from a chemical point of view,