Classification of Elements and Periodicity in Properties Test - 33

Be and Mg have $$\displaystyle \left [ He \right ]2s^{2}$$ and $$\displaystyle \left [ Ne \right ]3s^{2}$$ fully filled configuration respectively.
2s and 3s orbitals are filled to their capacity and they don't need any more electron to gain stability.
Be and Mg are unable to accept electron because they want to lose an electron to get the nearest nobel gas configuration.

The decreasing order of electron affinity of $$F, Cl,$$ and $$Br$$ is $$Cl$$ > $$F$$ > $$Br$$
In general, the electron affinity decreases down the group but the electron affinity for chlorine is more than that for fluorine,  because in $$F$$, due to the small size of the atom, the electron is already crowded. The entry which leads to the absorption of some energy, so the energy released is less than what would be expected.

$$X=2,8=10$$:  It is the electronic configuration of neon.
$$Y=2,8,7=17$$: It is the configuration of the halogen family of chlorine atom which is non-metal
$$Z=2,8,2=12$$: It is the configuration of alkaline earth metals of magnesium atom which is metal.

A Diagonal Relationship is said to exist between certain pairs of diagonally adjacent elements in the second and third periods of the periodic table. These pairs (Li & Mg, Be & Al, B & Si etc.) exhibit similar properties; for example, Boron and Silicon are both semiconductors, form halides that are hydrolyzed in water and have acidic oxides.  Such a relationship occurs because crossing and descending the periodic table have opposing effects. On crossing a period of the periodic table, the size of the atoms decreases, and on descending a group the size of the atoms increases. Similarly, on moving along the period

 the elements become progressively more covalent, less reducing and more electronegative, whereas on descending the group the elements become more ionic, more basic and less electronegative. Thus, on both descending a group and crossing by one element the changes cancel each other out, and elements with similar properties which have similar chemistry are often found - the atomic size, electronegativity, properties of compounds (and so forth) of the diagonal members are similar.

The chemistry of lithium is very similar to that of magnesium even though they are placed in different groups. Its reason is that the ratio of their charge to size is nearly the same

(A) Fluorine with electronic configuration $$1s^22s^2p^5$$ will form a most stable monovalent anion.
(B) Oxygen with electronic configuration $$1s^22s^2p^4$$ will form a most stable bivalent anion.
(C) Chlorine with electronic configuration $$1s^22s^2p^63s^23p^5$$ will form a most stable monovalent anion.
(D) Nitrogen with electronic configuration $$1s^22s^2p^3$$ will form a most stable trivalent anion.

The higher the metal in the series, the more reactive it is and the more vigorously it reacts with water, oxygen and acid.  A metal in the activity series can displace any metal below it in the series from its compound. The elements potassium, sodium, lithium and calcium are very reactive and they react with cold water to produce hydroxides and hydrogen gas. . The metals above hydrogen are more reactive than hydrogen. These metals can displace hydrogen from acids or water and liberate hydrogen gas. The metals copper, silver gold and platinum are less reactive than hydrogen and they do not replace hydrogen from water or acid.

Compound of a metal M formed $$M_{2}O_{3}$$ . It represent that M have 3 valency electrons. So the nitride formed will be MN.

In a period the elements are arranged in the increasing order of nuclear charge, increasing order of number of electrons and increasing order of atomic number.