Matter and Atoms 4-1

What is Matter? Matter – a term used to describe anything that has mass and takes up space Not matter Light Heat Energy

Early Ideas Democritus Universe made of empty space and tiny bits of stuff Atom – Greek word meaning “can not divide”

Atom Atom – a small particle that makes up most types of matter

Conservation of Matter 2,000 years pass Lavoiser – showed that no change in mass during chemical reactions Example – log burning

Proust Proust – matter is made of small particles that behave in ways that can be predicted and measured

Dalton’s Models of an Atom John Dalton – 1st model of an atom All of the atoms in something are identical Atoms of different elements are different from each other

Size of an Atom 1980’s – electron microscopes Allowed Scientist to see an atom

Inside an Atom Nucleus – center of an atom Contains protons and neutrons Proton – particle with a positive charge (+) Neutron – particle with no charge (0) Most of mass

Inside an Atom Electrons – particle inside an atom with a negative charge Equal number of protons and electrons Located in electron cloud