1.1 What is Molybdenum?
Molybdenum is a naturally-occurring metal that can be found in small amounts in rocks and soils. It is also present in plants, animals and bacteria. The element was discovered in 1778 by Carl Wilhelm Scheele. This element is a silvery-white (Fig. 2) high melting metal and classified as a ‘Transition Metal' and is located in group 6 and period 5 of the periodic table, it has an atomic number of 42 and atomic mass of 95.96 amu as seen in Fig.1. Transition metals are generally described as ductile, malleable and able to conduct electricity and heat.
Fig. 1: Expression of atomic mass and atomic number of molybdenum (en.wikipedia.org)
Molybdenum is obtained from Molybdenite MoS2, Wulfenite PbMoO4, PowelliteCa (Mo, W)O4. Its crustal abundance is estimated to be around 1.5 mg/kg or less where an estimate of 1.4 mg/kg is for the upper crust and 0.6 mg/kg is for the lower crust. There are seven naturally-occurring stable isotopes: 92Mo, 94Mo, 95MO, 96Mo, 97Mo, 98Mo and 100Mo of which 98Mo is the most abundant at 23.78%, followed by 96Mo at 16.653%, 92Mo at 15.84% and 95Mo at 15.72% of the total mass.
Molybdenum is an essential trace element in human, animal and plant nutrition. Both deficiencies and excesses can cause health problems, so there is considerable interest in the level of Mo and its activity in the environment. For example, 25µg day-1Mo is required by humans (WHO, 1996); symptoms of Mo deficiency include coma and night blindness. Conversely, excessive Mo reduces the uptake of copper in the human body and leads to skeletal deformities (WHO, 1996). In plants, Mo has a role in nitrogen fixation, but high Mo levels in vegetation can induce Cu deficiency in grazing animals.
1.2 properties of Molybdenum
Key properties include:
Symbol of Element : MoAtomic number : 42Atomic mass : 95.94 amuMelting point : 289 k (2623 0C , 4753 0F)Boiling point : 4912 k (4639 0C , 8382 0F)Number of protons/ electrons : 42Number of neutrons : 54Crystal structure : cubicHigh density of 10.2 g/cm3Phase at STP is solidGood thermal conductivityGood electrical conductivityGood hot strengthGood strength and ductility at room temperature.THE risk OF EXCEEDANCE OF THE WHO HEALTH-BASED VALUE OF 70µG/L MO.
INSTRUCTIONS AFTER PAYMENT
- 1.Your Full name
- 2. Your Active Email Address
- 3. Your phone Number
- 4. Amount Paid
- 5. Project Topic
- 6. Location you made payment from