Periodic Properties Test - 12

The neutron/proton ratio does not reflect the periodicity of elements. Rest are all periodic properties of elements. The neutron-proton ratio (N/Z ratio or nuclear ratio) of an atomic nucleus is the ratio of its number of neutrons to its number protons. It basically increases with the increase in atomic number unevenly.

Electronic configuration for element with atomic number 6 is 1s²2s²2p². It belongs to p-block with s²p² configuration. so it is placed in 14th group or IV A.

It belongs to p⁻ block since last electron is filled in p⁻ orbital and belongs to 3rd period as n = 3. Electronic configuration s²p⁴ belons to 16^th group.

As last electron is filled in 3p−orbital so it belongs to p-block. s-block and p-block elements are representative elements.

Electronic configuration for an element with atomic number 55 is [Xe]6s¹ . So it belongs to s-block since it has last electron in s-orbital.

Mg,Ba and Ca belongs to alkaline earth metals family.

• Valence electrons: Each group is characterized by its valence electrons, i.e., the number of electrons in the outermost shell of the elements are the same within a group. Thus, the common oxidation states for the elements of the same group are fixed.
  Due to the same number of valence electrons, elements of the same group show similar chemical properties.
• Atomic size: Moving down the group, a new shell is added with each period. The electron in the new shell also increases shielding. Therefore, the 
  Z_eff​ decreases along with which the attractive force of the nucleus decreases, and thus the size increases.
• Density: Density = Mass/Volume. Moving down the group, mass as well as volume increases. Therefore, density depends on the dominating factor. Usually, down the group, density increases, i.e., the effect of mass dominates.
• Metallic character: Moving down the group, the nuclear attractive force on outer electrons decreases due to a decrease in Z_eff​ which is due to an increase in shielding by outer valence electrons. As a result, the oxidation potential decreases down the group, and therefore, metallic character increases.

These are isoelectronic ions (ions with same number of electrons) and for isoelectronic ions, greater the positive nuclear charge, greater is the force of attraction on the electrons by the nucleus and the smaller is the size of the ion. Thus, Al³⁺ has the smallest size.

Due to poor schielding of (n – 2)f – electrons, the size of Zr and Hf are same. Hence the actual radii is different. Due to the contraction the radius turns same.

Do you remember the definition of isoelectronic? As the name suggests two entities are said to be isoelectronic if they have the same number of electrons.

As the nuclear charge in isoelectronic species increases the attraction between the nucleus and the electrons increases, bringing the electrons closer to the nucleus, therefore resulting in a decrease of the radius of the species.