Anatomy of the Atom
Learning Goals
 I will be able to identify parts of the atom.
 I will be able to draw Bohr-Rutherford diagrams.
 In each atom, there are three subatomic particles:
Particle
Charge
Size/Mass
Symbol
Inside the
nucleus
+1
1 a.m.u (atomic
mass unit)
p+
Electron
Outside the
nucleus
-1
1/2000 a.m.u
e–
Neutron
Inside the
nucleus
0
1 a.m.u
n0
Proton
Subatomic
Particles
Location
Shells
Anatomy of an
Atom
p+
no
Nucleus (proton and neutron)
Electron
 Every element is identified on the periodic table by its atomic
number.
Atomic
Number
 The atomic number tells us the amount of protons an atom of
that element has.
 No two elements have the same atomic number.
 The atomic number also tells us the number of electrons present.
Atomic
Number
 In all neutral atoms, the # of protons = the # of electrons.
Atomic Mass
 The atomic mass of an atom represents the total sum of the
protons and neutrons inside the nucleus.
Standard
Atomic
Notation
 Identifies important information
Atomic mass
4
Atomic number
2
He
 Write aluminum in standard notation.
Aluminum
 How many protons?
 How many electrons?
 How many neutrons?
Finding Nemo
… or Neutrons
 To determine the number of neutrons in an element … math!
 # neutrons = (atomic mass) – (atomic number)
BohrRutherford
Diagrams
1.
Draw the nucleus as a solid circle.
2.
Put the number of protons (atomic number) in the nucleus with
the number of neutrons (atomic mass – atomic number) under
it.
3.
Place the number of electrons (same as protons) in orbits
around the nucleus by drawing circles around the nucleus.
Remember:
1st shell – 2 electrons
2nd shell – 8 electrons
3rd shell – 8 electrons
4th shell – 18 electrons.
Example
 Phosphorous!
Learning Goals
 I will be able to identify parts of the atom.
 I will be able to draw Bohr-Rutherford diagrams.
Please
Complete …