Periodic Properties of the Elements: Trends in the Periodic Table
by:
George V Grant
The properties of the elements exhibit trends and these trends can be foreseen with the help of the periodic table. They can besides be explained and understood by analyzing the negatron configurations of the elements. This is because, elements tend to gain or lose valence electrons to accomplish the stable octet formation.
The properties of the elements exhibit trends and these trends can be foreseen with the help of the periodic table. They can besides be explained and understood by analyzing the negatron configurations of the elements. This is because, elements tend to gain or lose valence electrons to accomplish the stable octet formation.
In addition to this activity, there are two another important trends. First, electrons are added, one at a time, moving from left to right across a period. And, as this happens, the electrons of the outmost shell experience progressively strong nuclear attraction. As a result, the electrons become closer to the nucleus and much tightly bound. The second trend is the moving down a column in the periodic table, wherever
the outmost electrons become less tightly bound to the nucleus. And these trends explain the cyclicity ascertained in the elemental properties of atomic radius, ionization energy, negatron affinity, and electronegativity.
But, before going into that we need to cognize a bit much just about the above mentioned terms:
Atomic Radius
The atomic radius of an element is half of the distance between the centers of two atoms of an element that are in contact with each other. Generally, the atomic radius decreases across a period, from left to right and increases down a given group. Therefore, the atoms with the largest atomic radii are placed in Group I and at the lower half of groups.
Ionization Energy
Ionization energy or ionization potential is the energy required to wholly move out an negatron from a aeriform atom or ion. And, the closer and much tightly an negatron is bound to the nucleus, the much difficult it is to move out and the higher its ionization energy. Ionization energy is besides required to move out a second valence negatron from the monovalent
ion to form the bivalent ion, and so on.
Electron Affinity
Negatron affinity is the energy change that occurs once
an negatron is accessorial to a aeriform atom. It reflects the ability of an atom to accept an electron. And the atoms with stronger effective nuclear charge have a greater negatron affinity. Therefore, several generalizations can be ready-made just about the negatron affinities of certain groups in the periodic table. The alcalescent earths have low negatron affinity values. This is because they have filled sub shells. But, the halogens have high negatron affinities because of the addition of an negatron to an atom results in a wholly filled shell. Noble gases have zero negatron affinities, since each atom possesses a stable octet and wish not accept an negatron readily.
Electro negativity
An atom with higher electro negativity has a great capacity for attracting bonding electrons. Therefore, electro negativity is a measure of the attraction of an atom for the electrons in a chemical bond. It’s related to ionization energy. So, electrons with low ionization energies have low electro negativities because their nuclei do not exert a strong attractive force on electrons. And, elements with high ionization energies have high electro negativities. This is because of the strong pull exerted on electrons by the nucleus.
Therefore, electro negativity is dependant on the atomic number. As the atomic number increases, the electro negativity decreases, as a result of accrued distance between the valence negatron and nucleus. An example of an positive
element, i.e. one with low electro negativity, is cesium. And an example of a extremely
negative
element is fluorine.
Just just about the author:
Dr.George Grant is an full-fledged research worker in Bio-chemistry. He has done extensive researches and experiments in the field. He is a visiting faculty for several of the most putative Science colleges. For much information on Chemistry Tools and Definitions, Please Visit- http://www.chemicool.com
