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Periodic Properties

Copper and Gold, the two colored metals Copper and gold – the two colored metals In periodic table many metals are colorless(shiny white) and some metals have yellowish or bluish tinge. But particularly two metals, copper and gold, have distinct color. Copper is reddish brown and gold is yellow orange in color. The color of metals copper and gold is mainly due to absorption of light when a d electron jumps to an s orbital. Copper has a strong absorption at a slightly lower energy, with orange being most strongly absorbed and re‐emitted. Down the group there must be a increase in the gap between d and s orbitals. As usual the silver is white in color since an increase in energy absorption moves to UV region. But in case of gold due to relativistic correction the energy gap decreases and the electron emits in yellow‐orange region.

Learning Objectives

After completing the topic, the student will be able to:

  • Define the periodic properties such as atomic radius, ionization energy, electron affinity and electronegativity.
  • Distinguish van der Waals, covalent and atomic radii.
  • Explain the reason for the high magnitudes of ionization energy and electron affinity in some elements.
  • Recognize the periodic trends in properties of elements.
  • Explain the reasons for trends in the reactivity and behavior of elements in the periodic table.
  • Compare the properties of isoelectronic species.
  • Explain the relationship between ionization enthalpy and metallic character.
  • Understand the effect of electronegativity on chemical reactivity of elements.
Periodic table Periodic table Elements were discovered over the centuries. It took nearly 3 centuries to give the present look of the periodic table. This is a very well constructed table which can give a panoramic view of the properties of elements.
Periodic Properties

The periodic table is a table of the chemical elements in which the elements are arranged in order according to atomic number in such a way that the periodic properties (chemical periodicity) of the elements are made clear.

The standard form of the table includes periods (usually horizontal in the periodic table) and groups (usually vertical). Elements in groups have some similar properties to each other. There is no one single or best structure for the periodic table but by whatever consensus there is, the form used here is very useful.

The periodic table is a masterpiece of organized chemical information. The evolution of chemistry's periodic table into the current form is an astonishing achievement with major contributions from many famous chemists and other eminent scientists. Of the 116 elements in periodic table, chemists have grouped them as alkali metals, alkaline earth metals, transition elements, inner transition elements, p‐block elements (excluding halogens), halogens and noble gases. The location of these seven groups is in an inter‐linked manner based on their physical and chemical properties. For example, the 1st group of elements in periodic table is named for the alkaline (or basic) nature of their oxides and for the basic solutions the elements form in water.

General outer electronic configuration General outer electronic configuration Elements present in groups will have a general electronic configuration which would be followed by the elements present in the periodic table. Given above is the outer electronic configuration of the groups present in the table.
Periodic trends

The properties of the elements in a periodic table exhibit trends. These trends can be predicted using the periodic table and can be explained and understood by analyzing the electronic configurations of the elements.

Elements tend to gain or lose valence electrons to achieve stable octet configuration. Stable octets are seen in the inert gases or noble gases, of Group VIII of the periodic table. In addition to this activity, there are two other important trends. First, electrons are added one at a time moving from left to right across a period. As this happens, the electrons of the outermost shell experience increasingly strong nuclear attraction, so the electrons become closer to the nucleus and more tightly bound to it.

Second, moving down a column in the periodic table, the outermost electrons become less tightly bound to the nucleus. This happens because the number of filled principal energy levels (which shield the outermost electrons from attraction to the nucleus) increases downward within each group. These trends explain the periodicity observed in the elemental properties of atomic radius, ionization energy, electron affinity and electronegativity.

By observing the trends in the atomic radii of the elements in a period and those within a group of the periodic table we can predict the relative sizes of atomic and ionic radii within an isoelectronic series. We can also estimate certain physical properties of a particular element if the properties of elements above and below the given element in a group of elements are known.

Let us explore the variations in atomic radius, ionization energies, electron affinities in a periodic table.

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