Download Name: Date: Period: Page # Evolution of Atomic Theory (Changed

Name:
Date:
Period:
Page #
Evolution of Atomic Theory
(Changed over time as new discoveries were made)
Atomic Theory
 Ancient Greeks were the first to think about the nature of _____________
 Democritus proposed the idea of matter as small ____________
 _________: the smallest particle of an element
 As more evidence was collected over time, the theory and models were ________
 _______________________: atoms were like smooth, hard spheres that could not
be ____________ into smaller pieces
 All ____________ are composed of ___________ that cannot be divided
 Atoms cannot be ____________ or _____________ in a chemical change
 __________________ are composed of more than one ______________
 ______________ found smaller parts of atoms--atoms contain ______________
charged particles (_______________)e Berries in a muffin
 _______________ and the Nucleus: ________ __________ Experiment
 A few particles ______________ strongly Some bounced ________!!
 ______________ (no charge): located in ___________ of atom
 ____________ (+): positively charged particles ___________ the nucleus
 ____________ ___________: showed electrons could only have specific
amounts of __________, leading them to move in certain __________
 ____________ __________ Model: According to this model, the ____________
move _____________ in every direction around the nucleus
Page #
The Modern Atomic Model
 The Modern Atomic Model: ______________
 Discovered Neutron= same ___________ as proton
 Describes an atom as consisting of a nucleus that contains ___________
and neutrons ________________ by electrons
 Particle Charges:
 Protons charge is_____ Electrons charge is ______
 # of protons = # of electrons making the atom ___________
 # of _____________ does not always match #of P+ and e- because they
have no charge
 Comparing Particle Mass:
 atomic mass unit= amu (1 proton is _____ _____)
 Protons and neutrons make up nearly the entire _______ of the atom
 Scale and Size of Atoms
 The tiniest visible speck of ______ may contain 10 million billion ______
 Atomic Number
 # of ___________ in the nucleus of an atom
 Identifies an ___________
 Isotopes and Mass Number
 Isotopes: different number of _____________
 Mass number: sum of ____________ and _____________
Model of an Atom