Periodic Classification of Elements Test - 7

The elements with atomic numbers 57 to 71 are called lanthanide series and the elements with atomic numbers 89 to 103 are called actinide series.

Of all the noble gases, these two participate in the chemical reactions as the elements placed at the bottom of the group are very reactive in nature due to their high atomic numbers.

Being the elements of Period 2, both of them possess hgih metallic character.

On going down in a group of the periodic table, the electronegative character of elements decreases. So, Nitrogen at being the top of group 15 of the periodic table is most electronegative.

The halogens are located on the left of the noble gases on the periodic table. These five toxic, non-metallic elements make up Group 17 of the periodic table and consist of: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Although astatine is radioactive and only has short-lived isotopes, it behaves similar to iodine and is often included in the halogen group. Because the halogen elements have seven valence electrons, they only require one additional electron to form a full octet. This characteristic makes them more reactive than other non-metal groups.

When one electron has been removed from the neutral gaseous atom, the positively charged ion formed has one electron less than the number of protons in the nucleus. As a result, the electrostatic attraction between the nucleus and the remaining valence electrons increases. Therefore, the second ionization enthalpy is greater than the first one.

As the atomic number is 16, therefore, the valence electrons will be 6.

To complete its octet, it will gain two electrons and so  will exhibit Non-metallic character.

Elements of group 1 can readily lose 1 electron to complete their octet.

Elements of group 17 need one electron to complete their octet. So, both of them combine with each other and form ionic compounds.

On going down the group of the periodic table, the electronegative character of non-metals decreases.

Therefore, Fluorine being on the top in group 17 elements have the most electronegative character.

The elements on the extreme left of the periodic table have the largest size.

K, being on the extreme left of all the elements given have the largest size as on moving from left to right in a period, the size of atoms decreases.