2. History
• Discovered about 200 years ago (1766)
Henry Cavendish (1731-1810)
Antoine Lavoisier (1743-1794)
3. History
• In 1931, hydrogen was discovered to have
isotopes
vs.
Harold C. Urey (1893-1981)
Nobel Laureate 1934
Frederick Soddy (1877-1956)
Nobel Laureate 1921
4. Isotopes of Hydrogen
• Three common isotopes:
– Protium (H)
• common hydrogen
• 99.985% abundant
– Deuterium (D)
• one neutron
• 0.015% abundant
– Tritium (T)
• two neutrons
• 1x10-15
% abundant
9. Nuclear Magnetic Resonance
• Intensity of the absorption depends upon
the nucleus
Nucleus Natural Abundance Relative Sensitivity
1
H 99.985 1.0
13
C 1.108 0.016
19
F 100 0.83
31
P 100 0.07
11. Properties of Hydrogen
• Periodic table placement
– reasons to place the element in both Group
1(alkali metals) and Group 17 (halogens)
Argument for Placement Argument Against
Placement
Alkali Metal Group forms monopositive ions is not a metal
has a single s electron does not react with water
Halogen Group is a nonmetal rarely forms a
mononegative ion
forms a diatomic
molecule
is comparatively
unreactive
12. Properties of Hydrogen
• Colorless, odorless gas
– m.p. -259°C
– b.p. -253°C
• Relatively non-reactive
– diatomic bond energy of 436 kJ/mol
14. Reduction Reactions of
Hydrogen
• Acts to reduce many metallic elements
CuO(s) + H2(g) → Cu(s) + H2O(g)
• Can also reduce double and triple bonds
with a catalyst
H2C=CH2(g) + H2(g) → H3C—CH3(g)
33. Clathrates
• a substance which is trapped in the crystal
lattice of another substance
– from “clathratus”
• enclosed behind bars
• gas hydrates
– methane
– noble gases
34. Biological Aspects of Hydrogen
Bonding
• Hydrogen’s properties play two key roles to
the existence of life
– closeness in electronegativity to carbon
– ability to form hydrogen bonds
35. Reaction Flowchart
• Shows the different types of reactions of a
certain species
H2
NaH
NH3
Cu
H2OHF
TiH1.9
O2F2
Na
CuO
N2Ti