Electronegativity
Atoms like electrons: electronegativity. The graph shows the ability of each atom to attract the electrons of a bond. What conclusions can you draw?
Atoms like electrons: electronegativity. If you hover the mouse over the periodic table you will see the ability of each atom to attract the electrons of a bond. What conclusions can you draw?
The original interactive periodic table, made in Flash, no longer works in current browsers; the image shows one of its views.
The points that appear on the graph show a value of electronegativity for each element. Electronegativity is a property atoms show when they are bonded to others. The atoms bond together through sharing more or less their outermost electrons. Electronegativity gives us an idea of the capacity that atoms have to share those external electrons. If an atom with large electronegativity joins another with lower electronegativity, the bonding electrons will be shifted towards the atom of higher electronegativity.
Electronegativity increases very significantly as you progress through a row of the periodic system.
At the beginning of a row of the periodic system the outermost electrons of the elements are on a new layer, further from the core. If these elements share those electrons, the attraction they can exert on them will be small and, therefore, their electronegativity is low.
But, as we approach the end of a row of the periodic system, atoms get closer to the situation of having a layer of electrons complete, which is a very stable situation. Thus, they will have a strong tendency to attract towards themselves the electrons they share with other atoms to form a bond. Besides, as you progress through a row of the periodic system, the number of protons increase in the nucleus and, therefore, their ability to attract the electrons of a bond.
- Electronegativity decreases slightly as you go down a column (group) of the periodic system.
The lower down the periodic table, the further from the nucleus is the shell of the outermost electrons the atoms use to form bonds with other atoms. The distance from the core makes its attraction lower and therefore the electronegativity decreases.
The effect over one period (row) is much greater than over along a group (column) of the periodic system.
- The atoms at the end of a row do not have electronegativity.
Noble gases do not combine with other atoms because they have the outermost electronic layer complete. This situation is very stable and they do not need to "get it" by bonding other atoms. Therefore, they could not be assigned an electronegativity value.