Download the Atom - East Aurora School District 131

THE
ATOM
THE ATOM
 The
Smallest Particle Of An Element
 Cannot
Be Broken Down Into Smaller
Pieces
 Atoms
of Each Element Are All Identical
THE ATOM
 Electrically
 Electrons
 Size
Neutral
(Negative)
= Protons (Positive)
of An Atom Depends Upon the
Number of Electrons In the Electron
Cloud
PARTS OF THE ATOM
Nucleus
Central part of the atom
Positively charged
Contains Protons and Neutrons

PARTS OF THE ATOM
Protons
Number Identifies Each Element
Positive Charge
Found in Nucleus
Mass = 1 amu
Same Mass as Neutron

PARTS OF THE ATOM
Neutrons
No Charge
Found in Nucleus
Mass = 1 amu
Same Mass as Proton

PARTS OF THE ATOM
Electrons
 Negatively
Charged
 Found in Electron Cloud
 Mass = 1/1837 amu
 Virtually No Mass
Atomic
Number
 Number
 Each
THE ATOM
of Protons in the Element
Element Has Its Own Atomic #
 Identifies
Each Elements
 Elements
Are Arranged in Order of
Increasing Atomic Number
AMU
ATOMIC MASS UNITS
 The
Mass of An Atom Is Very Small
 The
Mass of an Atom is Measured in
AMUs.
 One
AMU = 1/12 of the mass of a
Carbon-12 atom
ATOMIC MASS
 The
average of all the isotopes of the
Element
MASS NUMBER
 The
Sum of the Number of Protons and
Neutrons In The Nucleus
 Neutrons

= Mass Number - Atomic Number
Each Element Has Its Own Mass Number
ATOMIC THEORY
Democritus – First to come up with the term
“atom”
 “Atomos” – means cannot be divided

LAW OF CONSTANT COMPOSITION