Hydrogen

Question 1

Chemistry Of Hydrogen

Hint: Description of the gas
Various oxidation states
Number and name of isotope(s)

Answer 1

It is a colourless, odourless but flammable gaseous substance
It has 3 oxidation states; H+ ion(1s0), a neural H atom(1s1) and H- ion(1s2)
Has 3 isotopes; Protium, Deuterium & Tritium

Question 2

Hydrogen Placement

Hint: 10 points
Can hydrogen be placed as a metal or non-metal.?
Where is Hydrogen placed on the periodic table (and what are the 2 reasons)
What makes is hard to decide Hydrogen’s position in the periodic table.
Its first ionization energy; the largest and smallest ionization energy on the periodic table
Its electronegativity; the most electronegative and the least electronegative//most electropositive
On the basis of …, it is tempting to classify H as a …
The reason it can be classified as a Group IV element
Hydrogen is best treated as…

Answer 2

It is difficult to classify hydrogen as a metal or non-metal
In Group IA and VIIA; -In Group IA because it forms compounds that are analogs of alkali metal compounds & -In Group VIIA because it forms hydrides that are analogs of halogen compounds
Due to its physical properties, it is hard to decide the position of H in the periodic table.
Its first ionization energy is 1312kj/mol; the largest is 2372kj/mol & the smallest is 376kj/mol.
Its electronegativity is 2.20 halfway between the most electronegative; 3.98 & the least electronegative; 0.7
Electronegativity.. Semimetal
On the basis of having a half-filled shelled electron, its structure resembles that of the Group IV elements
A group on its own

Question 3

Preparation Of Hydrogen

Hint: 4 points

Answer 3

Reaction between an active metal and water
Reaction between a less active metal and a strong acid
Reaction between an ionic metal hydride with water
Decomposing water into its elements with an electric current (Electrolysis)

Question 4

Physical Properties

Hint: Description
Density ( Comparison with air)
Nature of gas in combustibility & atomicity
Type of bond its molecule has
Atomic mass and molecular weight
Solubility in organic solvent and in water
Boiling Point
Ionization Enthalpy
Vapour Density
Molecular Mass

Answer 4

A colourless, odourless, tasteless and non poisonous gas
The lightest known gas(14.5× lighter than air)
A combustible diatomic gas
Its molecule is formed by covalent bond
Atomic Mass: 1.008amu & Molecular Weight: 2.016g
It is slightly more soluble in organic solvent than in water
Boiling Point: -253°C
Ionization Enthalpy: 1312kj/mol
Vapour Density: 1
Molecular Mass: 2

Question 5

Chemical Properties

Hint; Reactivity ability (Reason)
Most reactions of H2 involve.., where the .. first reacts with..(E.g)
Combination of H2 with metals to form … at … temperatures
Combination of H2 with … (E.g)

Answer 5

It is not very reactive (due to the strength of the H-H covalent bond)
Catalysis.., catalyst.., hydrogen
(E.g Manufacture of Ammonia[Activated Fe as catalyst], Hydrogenation Of Unsaturated Organic Compounds & Production Of Methanol by reducing CO2 with H2[Cu//Zn as catalyst at 300°C])
Metal hydrides//Interstitial Hydrides.. High
Halogens.. (E.g Direct combination of H2 with Cl2)

Question 6

Hydrides

Hint: Definition
Determining factor
Types

Answer 6

Compounds Of Hydrogen
The type of hydride depends on the type of bond formed
Types:
1. Ionic
2. Covalent (Intermediate)
3. Interstitial (Metallic)