Atomic Theory continued
- Atoms have three parts or “sub-atomic particles”
Particle
Charge
Mass
Location
Proton
positive
1 amu
Nucleus
Negative
1 amu
.0001 amu
(negligible)
Nucleus
Electron
Cloud
Neutron
Electron
- A few things to note:
o Protons and neutrons have the same mass
o Protons and neutrons are both located in the
nucleus
o The mass of an electron is so small compared to
that of protons and neutrons that we say it is
“negligible”
- Any atom can be divided into two regions; nucleus
and electron cloud.
- The Nucleus…
o contains almost all the mass
o is positively charged
o Occupies 1/100,000 of the total volume of the
atom. “a marble at the center of a football
stadium
- The Electron Cloud…
o Occupies the remaining volume of the atom
o Can be further subdivided
- While the electron cloud makes up 99.999999% of
the volume of an atom, this volume is not filled with
electrons. It only represents the region where the
electrons can be found at any given instant. In other
words, the electrons take up almost none of that
space.
- 99.9999999% of atoms are empty space.(see Rutherford’s
gold foil experiment)