What is matter all composed of?
Small particles called atoms.
What are atoms?
The smallest unit of an element that can participate in a chemical change.
How are all elements characterized?
They each contain a single of type of unique atom which has a mass that is also a characteristic of the element.
What dose a macroscopic sample of an element contain?
A large number of of atoms having identical chemical properties.
How can we tell each elements from each other.
They each contain atoms of different properties.