USES OF DIOXYGEN

• Dioxygen is extremely vital for processes like combustion and respiration.
• Dioxygen is mixed with carbon dioxide or helium to be used for artificial respiration.
• It is used in the manufacture of many metals.
• It is highly used in oxy-acetylene welding and metal cutting.
• Dioxygen is used to oxidise ammonia in the manufacture of nitric acid.
• It is used in oxygen cylinders, which are widely used in hospitals, high-altitude flying and in mountaineering.
• Liquid oxygen is an important constituent of the fuel used in rockets.

O is the symbol of oxygen which has a valency of -2.

Each oxygen combines with the other to complete its octet.

Now, if one atom of O conbines with the other.they both need 2 electrons each to be stable.

Thus  covalent bond are formed between the two atoms,and a diatomic molecule is formed.

This molecule  is reffered to as di - oxygen.

Sulphuric acid is called the King of Chemicals because it is used in the preparation of a very large number of other useful chemicals such as hydrochloric acid, nitric acid, dyes, drugs etc. In fact the annual production of shulpuric acid in a country is a measure of the economy of the country.

Oxoacids are basically acids that contain the element oxygen. As such, Phosphorus is known to form a number of oxoacids, for example: H₃PO₄, H₃PO₃, etc. In oxoacids of phosphorus, it is tetrahedrally surrounded by other atoms. Generally, all these acids are known to form at least one P=O bond and one P–OH bond.

Ozone

It is represented as O₃. It is found in upper atmosphere.

Preparation:

• It is prepared when ultraviolet rays. They react with oxygen of upper atmosphere and splits oxygen molecule in oxygen atoms. Then this oxygen atom combines with oxygen molecule to form ozone:
• 3O₂ ---> 2O₃
• Oxygen   Ozone
• The reaction is endothermic approx. 142.7kJ of heat is needed.
• For preparing pure ozone we use ozoniser, in which the electric spark is passed through oxygen gas and we get ozone.

Dioxygen plays a vital part in the existence of life. It is a highly reactive non-metal and it is a member of the chalcogen group on the modern periodic table. Oxygen is diatomic molecule and hence two atoms of the elements combine to form dioxygen. It is the third most abundant element in the universe.

Around 21% of the earth’s atmosphere consists of this gas in its free state. Chemical formula of oxygen is O2. It is the most abundant element found in the earth’s crust.

Dioxygen plays a vital part in the existence of life. It is a highly reactive non-metal and it is a member of the chalcogen group on the modern periodic table. Oxygen is diatomic molecule and hence two atoms of the elements combine to form dioxygen. It is the third most abundant element in the universe.

Around 21% of the earth’s atmosphere consists of this gas in its free state. Chemical formula of oxygen is O2. It is the most abundant element found in the earth’s crust.

Halides are binary compounds that are of which one part is an element another part is the halogen atom. A radical is less electronegative compared to that of halogens which form astatine, bromide, fluoride and chloride. Most of the salts are halides. Various halide compounds are tested using silver nitrate solution. Some include Kl, KBr, and KCl.

Acidic nature: Due to the decreasing bond dissociation enthalpy, acidic character of group 16 elements increases down the group.

                                    H₂O < H₂S < H₂Se < H₂Te

• Electron Gain Enthalpy: The electron gain enthalpy decreases with increase in the size of the central atom moving down the group. Oxygen molecule has a less negative electron gain enthalpy than sulfur. This is on the grounds that Oxygen, because of its compressed nature encounter more repulsion between the electrons effectively present and the approaching electron.

• Ionization Enthalpy: Ionization enthalpy decreases with increase in the size of the central atom. Therefore, it decreases as we move from Oxygen to Polonium since the size of the atom increases as we move down.

• Atomic and Ionic Radii: The atomic and ionic radius increases as we move from Oxygen to Polonium.

The elements of group 15: oxygen (O), sulphur (S), selenium(Se), tellurium (Te) and polonium (Po) having general electronic configuration ns²np⁴, are known as the oxygen family. All these elements collectively are also known as chalcogens. Polonium is a radioactive element.

Van der Waals forces are weak intermolecular forces that are dependent on the distance between atoms or molecules. These forces arise from the interactions between uncharged atoms/molecules.

For example, Van der Waals forces can arise from the fluctuation in the polarizations of two particles that are close to each other

Electron gain enthalpy of an element may be defined as the energy released when a neutral isolated gaseous atom accepts an extra electron to form the gaseous negative Ion i.e. anion.It is denoted by

 Δ eg H.

Greater the amount of energy released in the above process, higher is the electron gain enthalpy of the element. The electron gain enthalpy of a element is a measure of the firmness or strength with which an extra electron is bound to it.

Electron gain enthalpy is measured in electron volts per atom or kJ per mole.

The process of adding an electron to the atom can be either exothermic or endothermic.

Energy is released when an electron is added to the atom. Therefore, the electron gain enthalpy is negative.

The electron gain enthalpy for halogens is highly negative because they can acquire the nearest stable noble gas configuration by accepting an extra electron.

Noble gases have large positive electron gain enthalpy because the extra electron has to be placed in the next higher principal quantum energy levels there by producing highly unstable electronic configuration.

After the addition of 1 electron, the atoms becomes negatively charged and the second electron is to be added to a negatively charged Ion. But the addition of second electron is opposed by the electrostatic repulsion and hence the energy has to be supplied for the addition of second electron. The second electron gain enthalpy of an element is positive.

When an electron is added to oxygen atom to form  O¯ ion ,energy is released.But when another electron is added to O¯ ion to form O2- ion, the energy is absorbed to overcome the strong electrostatic repulsion between the negatively charged  O¯ ion and second electron being added.