In the periodic table, metallic character of the elements shows one of...
Down to the group the atomic size increases. ... Even the tendency to lose electrons from the outermost valence shell also gets increased as we move down to the group. So, the metallic character gets increased as we move down to the group. Hence the correct answer is; metallic character increases down a group.
In the periodic table, metallic character of the elements shows one of...
Metallic Character in the Periodic Table
The metallic character of an element refers to its ability to exhibit properties characteristic of metals, such as high electrical and thermal conductivity, luster, malleability, and ductility. The metallic character generally increases as we move down a group on the periodic table and decreases as we move across a period.
Trends in Metallic Character
Down the Group:
As we move down a group on the periodic table, the metallic character of elements increases. This is primarily due to the increasing atomic size and the decreasing effective nuclear charge experienced by the valence electrons. The larger atomic size results in a greater distance between the valence electrons and the nucleus, weakening the attraction and making it easier for the electrons to be lost. Additionally, the decreasing effective nuclear charge reduces the attractive force between the nucleus and the valence electrons, further facilitating the loss of electrons. Therefore, elements at the bottom of a group tend to have higher metallic character.
Across the Period:
As we move across a period on the periodic table, the metallic character decreases. This is mainly because of the increasing effective nuclear charge experienced by the valence electrons. Although the atomic size generally decreases across a period, the increasing effective nuclear charge has a greater impact on the metallic character. The greater positive charge in the nucleus exerts a stronger pull on the valence electrons, making it more difficult for the electrons to be lost. As a result, elements on the right side of a period are less likely to exhibit metallic properties compared to elements on the left side.
Example:
Let's consider the trend in metallic character for Group 1 (alkali metals) and Group 17 (halogens) elements:
- In Group 1, as we move down from lithium to francium, the metallic character increases. Lithium is a relatively weak metal, while francium is predicted to be the most metallic element.
- In Group 17, as we move across from fluorine to iodine, the metallic character decreases. Fluorine is a non-metal, while iodine exhibits some weak metallic properties.
Conclusion:
In summary, the metallic character of elements generally increases down a group and decreases across a period. This trend can be explained by the interplay of atomic size and effective nuclear charge. The larger atomic size and decreasing effective nuclear charge down a group make it easier for valence electrons to be lost, leading to higher metallic character. Conversely, the smaller atomic size and increasing effective nuclear charge across a period make it more difficult for valence electrons to be lost, resulting in lower metallic character.