Science : Ch 05 – Periodic of Classification of Elements

There are 18 vertical columns, known as groups and Ǫ horizontal rows familiar as periods in the modern periodic table.

Atomic number X- 12 ,Y-17 Number of protons X-12, Y-17 Number of electrons X-12,Y- 17 Electronic configuration 2, 8, 2 2, 8, 7 Valence electrons X-2,Y- 7 Valency X- 2,Y- 1

Germanium element found a place in the periodic table later in the place of Eka–silicon in Mendeleev’s periodic table.

The element with electronic confguration 2, 8 has octet confguration, so it must be an inert gas, i.e., neon, which is placed in group 18.

The atomic number of F, O and N are Ǭ, 8 and Ǫ respectively and they belong to the same period i.e. 2nd period. The atomic radius decreases in moving from left to right along a period.

Flourine has Ǫ electrons in the outermost orbit. Its atom size is the smallest too. Since it is the most electronegative element, it does not lose an electron easily.

All these elements belong to the same period, in which non-metallic character increases from left to right.   Li, O, C, Be and F belong to the same period, i.e., 2nd period. In a period on moving from left to right, non-metallic character increases.

The elements boron (B), silicon (Si) and germanium (Ge) exhibit intermediate properties of metals and non-metals, therefore, they are called as metalloids

Atomic number 14 (electronic confguration of 2,8,4) is for silicon element, which is a metalloid and exhibit properties of both metal and non-metal

As we move down in a group, the metallic nature of elements increases.  Be, Mg and Ca are present in the same group (group 2 of the modern periodic table).