Chemistry of Non Metals
Introduction
⁕ Introduction to Oxygen
↪ Greek, Oxys - Sour, genas - produce: Acid Producer
| Symbol | O |
| Atomic number | 8 |
| Atomic mass | 16 amu |
| Valency | 2 |
| Electronic configuration | 1s2 2s2 2p4 |
⁕ Occurrence
↪ English chemist Joseph Priestly detected oxygen in 1774 as a nonmetallic element.
↪ Oxygen is the most abundant element and it is about 47% by mass on the earth crust in the form of oxides and oxysalts.
↪ It occurs 23% by weight in free molecular form in air and about 86% by weight in combined form on oceans.
↪ Natural oxygen is a mixture of three isotopes:
16O(99.76%), 17O(0.04%) and 18O(0.2%).
↪ Oxygen is the most essential for life and it supports respiration.
⁕ Position of Oxygen in Periodic table
↪ Oxygen is a nonmetallic element having atomic number 8 and mass number 16.
↪ Its electronic configuration is: 1s2 2s2 2p4.
↪ The elements sulphur, selenium, tellurium and polonium also have general valence shell electronic configuration ns2 np4 and all of them belongs to group VIA.
↪ All these elements are collectively called chalcogens (ore forming) because metal occur in nature as the ores of oxides, sulphides, selenides and tellurides.
↪ Oxygen is the representative element of this family.
⁕ Electronic configuration and some properties of group VIA elements are given below:
| Element | Atomic Number | Electronic Configuration | I.P. (ev) | E.N. |
| O | 8 | [He] 2s2 2p4
|
13.6 | 3.5 |
| S | 16 | [Ne] 3s2 3p4
|
10.35 | 2.5 |
| Se | 34 | [Ar] 3d10 4s2 4p4
|
9.75 | 2.4 |
| Te | 52 | [Kr] 4d10 5s2 5p4
|
9.01 | 2.1 |