Non-metals - hydrogen, Chemistry

Assignment Help:

 

HYDROGEN

Hydrogen is the natural element in the Universe and is a major constituent of stars. It is relatively much less common on Earth but nevertheless forms nearly 1% by mass of the oceans and crust, principally as water and in hydroxide and hydrates minerals of the crust.

The dihydrogen molecule H2 is the stable form of the element under simple conditions, although atomic hydrogen may be made in the gas phase at high temperatures, and hydrogen may convert a metallic liquid or solid at extremely high pressures. At 1 bar pressure, dihydrogen condenses to a liquid at 20 K and solidifies at 14 K, these being the minimum boiling and melting points for any substance except helium. The H-H bond has a dissociation enthalpy of 436 kJ mol-1 and a length of 74 pm. That is the shortest bond known, and one of the strongest single covalent bonds.

Although it is thermodynamically capable of reacting with many compounds and elements, these reactions usually have a large kinetic barrier and needs elevated temperatures and/or the use of catalysts.

 

Hydrides of metals

 

Not every metallic elements form hydrides. Those that do will be classified as follows.

 

  • Highly electropositive metals have solid hydrides regarded as containing the H- ion. They have structures same to halides, although the ionic character of hydrides is undoubtedly much lower. As like LiH (rocksalt structure) and MgH2 (rutile structure ;).

 

  • Some f- and d- block elements form hydrides that are often metallic in nature, and of variable (nonstoichiometric) composition. As like TiH2 and CeH2+x.

 

  • Some heavier p-block metals form molecular hydrides similar to those of nonmetals in the same group, stannane (SnH4) being and digallane (Ga2H6), both of very low stability.

 

 


Related Discussions:- Non-metals - hydrogen

The ph scale, The pH scale: The equation: p Kw =14.00=pH+pOH is obtaine...

The pH scale: The equation: p Kw =14.00=pH+pOH is obtained by taking the negative logarithm to the base 10 of the autoprotolysis equation, where In general pX denotes -

Show egg foams application in food preparation, Q. Show Egg foams applicati...

Q. Show Egg foams application in food preparation? Foams need to be stable if they are to have a role in food preparation. Stability is enhanced if the surface tension is low,

Explain emanation spectrum of an atom, Q. Explain emanation spectrum of an ...

Q. Explain emanation spectrum of an atom? The emanation spectrum of an atom indicates that the energy it emits is quantized meaning that only certain quantities of energy can b

Dextrorotary compounds and levi rotary compounds, What are dextrorotary com...

What are dextrorotary compounds and Levi rotary compounds? Ans) Compounds that rotate the plane polarized light to the right are known as Dextro rotatory compounds and that rota

Eukaryotes vs prokaryotes-methylation of dna , 1. Acetylation of key protei...

1. Acetylation of key proteins is known to correlate with the gene expression in eukaryotes. What class of chromatin proteins is modified? What is the chemical nature of the acetyl

PEPTIDE BONDS AND HYDROLYSIS, I UNDERSTAND THE CONCEPT. I AM CONFUSED ABOUT...

I UNDERSTAND THE CONCEPT. I AM CONFUSED ABOUT A SPECIFIC EQUATION OR FORMULA TO SHOW HOW THE BONDS ARE BROKEN THROUGH HYDROLYSIS.

What sort of panel is required for acceptance tests?, What Sort of Panel Is...

What Sort of Panel Is Required for Acceptance Tests? Consumer panels are the best group to use for evaluating the acceptability of a product or a range of products because the

Stochiometry, How many grams of CO2 are produce if 42.0 mol of LiOH react?

How many grams of CO2 are produce if 42.0 mol of LiOH react?

Biodegradable polymers, Biodegradable polymers These are the polymers t...

Biodegradable polymers These are the polymers that are degraded through micro-organisms in an appropriate period so that biodegradable polymers and their degraded products do n

Electron Configuration and Periodic Properties, what are the signs associat...

what are the signs associated with electron affinity?

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd