Tag: p- block elements-ii

$2KNO _3\overset{\Delta}{\rightarrow}2KNO _2+O _2\uparrow$

Priestley discovered oxygen gas in 1774. When he heated mercuric oxide, he found that a gas was released that could reignite a glowing splinter. This gas was oxygen.

The level of mercury in the bell jar rose by one-fifth during the experiment performed by Antonie Lavoisier.

During the experiment performed by Joseph Priestley, the observation was that a colourless gas is collected in the jar i.e oxygen.

Joseph Priestley did not use bell jar in his experiment.

During discovery of oxygen, mercuric oxide was heated by focusing the sun rays on it.

Antonie Lavoisier was the first scientist who named oxygen gas.

Oxygen has $6$ electrons in the outermost shell. Its configuration is $2,6$.

$16p$ means $Z=16$

$18e$ means $2$ unit negative charge is present.

Hence, species is $S^{2-}$.

The melting points of group 16 elements generally increase down the group due to increasing van der Waals forces, but there are irregularities. The correct trend is O < S < Se < Te > Po.