Download PowerPoint_Atomic Structure

Atomic Structure
What’s in an atom?
History of the Atom
460 BC Democritus develops the idea of atoms
he pounded up materials in his pestle and
mortar until he had reduced them to smaller
and smaller particles which he called
ATOMA
(Greek for indivisible)
History of the Atom
1808 John Dalton
suggested that all matter was made up of
tiny spheres that were able to bounce around
with perfect elasticity and called them
ATOMS
History of the Atom
1898 Joseph John Thompson
found that atoms could sometimes eject a far
smaller negative particle which he called an
ELECTRON
Structure of the Atom
• Nucleus: The “core” of the atom
• The nucleus of the Atom contains 2 types of
particles.
• Proton: The particle in the nucleus having a
positive charge.
• Neutron: The particle in the nucleus that has a
neutral charge.
Using the Periodic Table
Look at the tile on the periodic table, Carbon,
for example:
Name of Element
Atomic Number
Symbol of Element
Atomic Mass
Terms
Atomic Number: How many protons are in an
element. For example, ANY atom that has
6 protons is always called Carbon.
Atomic Mass: How many neutrons AND protons
are in an element’s nucleus. This number is
an average of the different kinds of an
element.
Using the Periodic Table
Silicon has an Atomic Number of 14.
This means it has 14 protons
Silicon has an Atomic Mass of
about 28, so that means it has
28 protons and neutrons.
To find how many neutrons it
has, we subtract the Atomic Number from the
Atomic Mass.
So, 28 – 14 = 14 neutrons.
Atomic Structure
In an uncharged atom, the number of Electrons
is equal to the number of Protons.
For Carbon, atomic number 6, atomic mass 12.
A “typical” carbon atom will have 6 protons.
12 – 6 = 6 neutrons.
And 6 protons means 6 electrons.
Group Work
Work in your groups and have each member
write out and hand in the Element Name,
Element Symbol, and number of Protons,
Neutrons and Electrons for the following
Elements (Look in the back of your book):
Neon
Helium
Bromine
Potassium Mercury Tellurium
Cobalt
Tin
Zinc
Oxygen