![](../../../Slide%20Images/Didac%2003/Thumbs/D3%20M13.jpg)
Aim: To present the
first twenty elements of the Periodic Table using the Rutherford-Bohr model. |
|
|
The comments that were made about
atomic dimensions in connection with illustrations M11 and M12 are also
valid here.
Atomic radius decreases with increasing atomic number. In any period (row)
of the periodic table the atoms on the right -hand side are smaller than
those on the lefthand side. This is apparent from the atomic radii for the
elements of the third period given below,which are expressed in pm (picometres):
(picometer = 10-12 m)
![](Diagram/M13.jpg)
With the exception of helium, the s-electrons which form electron pairs in the ground
state are represented as unpaired so that chemical bonding can be explained simply.
|