CHM2046 - CHT 14 - Hydrogen Atom

second video for chm2026 chapter 14

Hydrogen can be located..

At the top of group 1A or group 7A of the periodic table since it has properties of both groups

Ionic Hydrides

This is when H2 directly forms with any alkali metal (1A group) or with the alkaline earth metals (Ca, Sr, and Ba)

They are rate and very reactive to air and water

Covalent Hydrides

H2 covalently bonds to the other atom of another element

Two types of covalent bonding 

• discrete molecular units (CH4 & NH3)

• complex polymeric structures ((BeH2)x)

1^H Isotope 

Protium (H

2^H Isotope

Deuterium (D)

3^H Isotope

Tritium (T)

All of hydrogen’s Isotopes …

contain one or two neutrons as well

Hydrogen Bonding

occurs when hydrogen is bonded to F,O,N

Characteristics in group 1A - Alkali Metals

• standard +1 oxidation number

• relatively high IE and EN (group 1)

• shares electrons when bonding with nonmetals to create covalent hydrides

Characteristics in group 7A - Halogens

• forms a hydride ion with metals to get -1 oxidation number 

• lowest EN in group 7 despite being at the top of group 

• accepts electrons when bonding with metals to create ionic hydrides

Hydrogens unique properties are because of its..

very small size

• high IE since there are no other electrons present for shielding 

• low EN since nucleus has only one proton to attract electrons 

• Hydrogen is a great reducing agent 

Metal with H^+1

Hydrogen oxidizes the metal by accepting electrons and forming H2 gas

• ex Al(s)+6HCl(aq) → 2AlCl3(aq) + 3H2(g)

Metal Hydride

Hydride ion reacts with water to form H2 gas and a hydroxide

• Ex. Al(s) + 6 HCl(aq) → 2AlCl3(aq) + 3H2(g)

Reduction by Hydrogen

H2 gas reduces metal ion and becomes H^+1

• Ex. PdCl2(aq) + H2(g) → Pd(s) + 2HCl