Structure of
Matter
Matter
3 states of Matter
Solid
Liquid
Gas
Matter
All matter is composed of
ELEMENTS.
All Elements are
composed of ATOMS.
Composition of an
Atom
An atom is made of 3
subatomic particles...
Protons – positive charge (1 amu)
Neutrons – neutral or no charge (1 amu)
Electrons – negative charge (0 amu)
Composition of an
Atom
All atoms have an atomic mass
Atomic Mass consists of the
protons and neutrons
Since the mass of an electron is so small, it is
NOT counted as a part of the atomic
mass...only protons and neutrons count
Composition of an
Atom
All atoms have an atomic
number
The atomic number tells you
the number of PROTONS and
ELECTRONS in a neutral
atom.
Structure of an Atom
Nucleus is the
center of the atom
Inside the nucleus are
the protons and
neutrons
The Electron Cloud
surrounds the
nucleus
+ + +
+
+ +
+
Electrons are found
on the energy levels
that make the electron
cloud
2–8–8
Bohr Model
Atoms
All atoms are neutral
which means...
All atoms have an equal
number of protons and
electrons.
Where do you find atomic
structure information?
On the PERIODIC
TABLE
Atomic #
Element Symbol
(First letter is ALWAYS capitalized. If it has two
letters, the first letter is capitalized and the
second letter is ALWAYS lower case.)
Element Name
Atomic Mass
5
B
Boron
10.81
Using the Periodic Table
5
B
Boron
10.81
Protons = 5
because atomic # is 5
Electrons = 5
because atomic # is 5
Neutrons = 6
because atomic mass is
11 and atomic # is 5,
SUBTRACT: 11 – 5 = 6