Periodic Table and Elements

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Because of its large size, the outermost electron of cesium is more loosely bound to the nucleus of the atom. Hence, it can be easily removed.

Generally alkali metals have low melting and boiling points. For example - sodium.

The melting points of the alkali metal halides decrease in the order: Fluoride > Chloride > Bromide > Iodide Thus, fluorides are the most stable, while iodides are the least stable.

Transition metals have the ability to utilise vacant d-orbitals. Thus, they exhibit variable oxidation states which enables the transition elements to associate with the reactants in different forms.

Oxygen is the second most electronegative element after fluorine.

Chlorine has 7 electrons in its valence shell and the valency is 1.  Both magnesium and oxygen have valency 2. The valency of aluminium is 3.

Greater the tendency to lose electrons, stronger is the reducing agent. Here the atom of sodium has the maximum metallic character. So, it is the strongest reducing agent.

$Cl^-$ is an anion. Hence, it is larger than its parent atom Cl.

Inert gases have zero electron affinity. Therefore, helium is an inert gas.

Valencies shown by copper are  + 1 and + 2.

Be, Z = 4 has maximum covalency of 4 while Al, Z = 13 has maximum covalency of 6.

Noble gases have a full valence electron shell, making them chemically inert or un-reactive under standard conditions.