BAKER HUGHES - Drilling Fluids Reference Manual

Water Based Drilling Fluids
Table 3-2
The Periodic Table
Types of Bonding
Chemical Bonding
Chemical reactions involve a rearrangement of the electron shells surrounding the atoms
involved. This rearrangement generally produces a more stable structure and links the atoms
together, thus producing a chemical bond.
The most stable configuration is found to be a completely full outer shell of electrons. Simple
chemical combination between elements can be explained by assuming that the atoms concerned
are trying to attain this state.
The so called “noble gases”, such as helium, neon and argon, which form group O of the periodic
table, already possess full outer electron shells. These elements are thus extremely un-reactive
and can only be made to combine with other elements under very specialized conditions. Other
elements can obtain the “noble gas structure” by losing, gaining, or sharing electrons.
Ionic Bonding
Ionic bonding involves a transfer of one or more electrons from one atom to another. Atoms
which have lost or gained electrons are ions.
Electrons are negatively charged and thus, an atom that loses an electron becomes positively
charged, as there are now more protons in the nucleus that there are electrons around it. A
positively charged ion is called a cation and is denoted by writing a “+” sign as a superscript after
the chemical symbol. Thus Na + is a sodium ion (one positive charge) and Mg 2+ is a magnesium
ion (two positive charges, i.e., two electrons lost).
Reference Manual
Baker Hughes Drilling Fluids
3-6 Revised 2006