Periodic Classification of Elements Test - 11

Aluminium belongs to group 13 and  period 3 of the periodic table.

Germanium is referred to as Eka-silicon.

Gallium has an atomic no. of 31

Magnesium is a major constituent of Chlorophyll.

Fluorine is the most electronegative element in the periodic table.

Lithium is the most electropositive element in the periodic table.

Neon has a stable outermost electronic configuration, so it belongs to noble gas family. 

Carbon is the major constituent of most of the organic compounds.

Electronic config of Ca - 2,8,8,2 i.e. it has two valence electrons.

Electronic config of Ne - 2,8 i.e. it has completely filled shells

Electronic config of K - 2,8,8,1 i.e. it has 1 valence electron

Hydrogen has 1 electron and 1 proton, so neutrons = 1-1 = 0

As the atomic size across a group increases, so the energy required to knock out the electron i.e. Ionization enthalpy decreases.

Across a group, the atomic size increases with the increase in atomic number.

Metals readily lose electrons to form positive ions, so they have high electropositive character.

Non-metals readily gain electrons to form negative ions, so they have high electronegative character.

Due to their stable inert gas configuration, they are highly unreactive. Therefore, both statements (A) and (B) are correct.

Isoelectronic ions are those which contains the same number of electrons.

O^2- = 8+2 = 10 electrons

N^3- = 7+3 = 10 electrons

Na⁺ = 11-1 = 10 electrons

F^- = 9+1 = 10 electrons

Isotopes of an element  are the atoms with same atomic number but different atomic masses. Being the atoms of the same element, they possess similar chemical proeprties.

³⁵₁₇Cl and ³⁷₁₇Cl are the isotopes of Chlorine.

According to Dobereiner's law of triads when elements are arranged in the order of increasing atomic masses, groups of three elements having similar chemical properties are obtained. The atomic mass of the middle element of the triad is equal to the arithmetic mean of the atomic masses of the other two elements. 

Li, Na, K form the triad of alkali metals and Cl, Br and I form the triad of halogens. 

Sodium and Potassium are the group 1 elements as they have 1 valence electron in their outermost shells.
Magnesium and Calcium are group 2 elements as they have 2 valence electrons in their outermost shells.
Sulphur and Oxygen are group 6 elements. 

Hydrogen has an anomalous behaviour, it can behave as a metal as well as a non-metal.

It has 1 electron and 1 proton but no neutrons.