HYDROGEN ELEMENT ESSENTIAL :
Hydrogen is the most abundant chemical element in the whole universe and tenth most abundant by mass on Earth, and it's lot of found in the oceans, minerals, and all forms of our life. The partial depletion of hydrogen element under normal conditions is DIHYDROGEN, it's molecular formula H₂, which is mostly occurs at trace levels in the Earth's at lower atmosphere. The Dihdrogen or Hydrogen molecule has many uses and it's produced naturally as a product of fermentation and as a byproduct of ammonia biosynthesis. It's often as the "FUEL OF FUTURE" On account of it's availability from fully renewable resources (eg) water and sunlight and it's clean and highly exothermic reaction with oxygen molecule (O₂) but the volatility and lower energy density of hydrogen molecule pose challenges for storage.
HYDROGEN ATOM IT'S ION:
The Hydrogen atom and it's proton H⁺, is always found in combination with Lewis base and it's highly polarizing, Hydrogen ion H⁻ is also highly plarizable.
There are three types of hydrogen : Hydrogen itself, (¹H), deuterium (D, ²H), and tritium (T, ³H), tritium is very radioactive isotopes. The lightest isotopes of hydrogen ¹H it's very occasionally called as a protium, and it's by far most abundant in the universe. The Deuterium has been variable natural abundance with average value of about 16 atoms in 100 000.
But tritium occurs to the extent of only 1 in 10²¹. The different types of names and symbols for this three isotopes reflect the significant difference in their masses and the chemical properties that stem from mass, such as rate of diffusion and bond - cleavage. Hydrogen nuclear spin ¹H (I= 1/2) is exploited in NMR spectroscopy and for identifying hydrogen - containing molecule and determined their structure.
The free hydrogen H⁺ proton ( cation) have very highly charge, and radius ratio and it's not surprising to find that it's very strong Lewis acid. Hydrogen are in the gas phase it readily attaches to other molecules and it's atom, it even attaching to He to form HeH⁺. The condensed between Lewis bases gives it the special role in chemistry. The Hydrogen molecular cation H₂⁺ and H₃⁺ having only transitory existence in the gas phase and are unknown solution. In contrast of H⁺ ion, which is highly polarized, the hydride ion H⁻ varies considerably depending on the atom to which attaching. The lack of core electrons or inner electrons to scatter X- rays it's means that bond distance and angels involves a H atom in a compound are different to measuring by X-ray diffraction, for this reaction, neutron diffraction is used when it's crucial to determine the precise position of hydrogen atoms.
HYDROGEN PROPERTIES AND IT'S REACTION :
Hydrogen is a unique atomic properties that in a special position in the periodic table. The Dihdrogen or Hydrogen molecule is inert molecule and it's reaction required to a catalyst or initiation by radicals.
Hydrogen atom is unique properties distinguish it from all other chemical elements in the periodic table, and it's often placed head at the group 1 because like the alkali elements, it's has only one electron in it's valence shell. That position, however doesn't not truly reflect the physical or chemical properties of the hydrogen element. It's ionization energy is too higher than those of the group 1 elements, so hydrogen is a not metal, although it's found naturally in metallic state where extreme pressure exists, such as the core of jupiter planet. In some version of the periodic table hydrogen place at head of group 17, because like the halogens and it's required only one electron to complete it's valence shell.
But the electron affinity of hydrogen elements lower than that of any of the elements of group 17 and the discrete hydride ion H⁻ is encountered only in the certain compounds. The reflect it's unique character, so we can consider the special place Hydrogen atom is in head of the periodic table. Because the hydrogen molecule (H₂) has a two electrons only, in the intermolecular forces between the hydrogen molecule are weak bond, and 1 atmospheric gas condenses to liquid only when cooled to 20 kelvin. If an electric discharge is passed through the hydrogen molecule gas at low pressure, this molecules dissociate, ionized and recombine, forming a plasma containing in addition to hydrogen molecule, spectroscopically observable amount of H, H⁺, H₂⁺, and H₃⁺.
The Hydrogen molecule has a high bond enthalpy (436kj mol-¹) and a short bond length (74pm). The high bond strengthen results in hydrogen molecule being a inert molecule. However, it's still more easier to dissociate hydrogen molecule is homolytically than heterolytically, because in heterocyclic dissociation energy is required to separate opposite charges.
H₂(ɡ) →H (ɡ)+ H(ɡ) ∆H = + 436 kj mol-¹
H₂ (ɡ)→ H⁺(g) + H⁻(g) ∆H =+ 1675 kj mol-¹
Because of it's inherently naturally inert, reaction of Hydrogen molecule doesn't occur readily and unless a special activation pathways have been provided. These pathways including homolytic or heterocyclic dissociation catalysed by molecules or active surfaces, and initiation of the radical chain reactions. The explosive reaction of H₂ with O₂ for instance reaction below
2H₂ (ɡ) + O₂(ɡ) → 2H₂O (ɡ) ∆H = -242 kj mol-¹
Proceed by a complex radical as chain mechanism. The Hydrogen element is an excellent fuel for larger rockets on account of it's high specific enthalpy, which is approximately three times that the hydrocarbon.
In addition to reaction results in dissociation of the H-H bond, and H₂ 6n also reacting reversibly reaction without cleavage to form DIHYDROGEN is a d- metal complexes.
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