hydrogen chp 10 Flashcards
The proton, H+
the high charge/radius ratio,
hard acid,
highly polarizing
very strong Lewis acid,
attacking atoms or molecules such as He
or H2
, to form HHe+ or H3
+ in the gas phase
The proton, H+
polarizing or polarizability
polarizing
- The hydride ion, H-
polarizing or polarizability
Highly polarizable
The radius depends on the atom attached
Properties and reactions of hydrogen 1A
It has one valence electron, however, it has
higher ionization energy (1312 kJ/mol), it is not a metal
Properties and reactions of hydrogen 17A
it can gain one electron forming hydride,
however, it has lower electron affinity (73 kJ/mol).
BP high or low
H2 has weak intermolecular forces, therefore its b.p is 20 K
Bond enthalpy and bond length
High bond enthalpy (436 kJ/mol)
short bond length (74 pm)
Homolytic dissociation
H2
(g) -> H(g) + H(g) rH = +436 kJ/mol
Heterolytic dissociation
H2 (g)-> H+ (g) + H- (g) rH = +1675 kJ/mol
Activation energy
high
rxn w/02
2H2
(g) + O2
(g) -> 2H2O(g) rH = - 242 kJ/mol
inert molecule
reactions require catalyst or initiations by radicals
saline hydrides
li
na
k
rb
cs
mg
ca
sr
ba
intermediate hydrides
cu
zn
molecular hydrides
be
+
all non-metals
metallic hydrides
sc ti v cr - - - ni
y zr nb - - - - pd
la hf ta
unknown hyrdies
8A
saline
H+ s block
molecular
H+ Be+ p block
metallic
H+ d-block
H+ f block
molecular hydrides bond
covalent
saline hydrides property
non-volatile
con-conductive
metallic hydrides property
non-stoichiometric
conducting
Complex ion formation
BH4–> tetrahydrate borate-> borohydrate
AlH4–> tetrahydrate aluminate-> aliminium hydrate
1A+H delta G formation
aşağı indikçe artar
less negative
2A+H delta G formation
aşağı indikçe azalır more negative