How to calculate melting points?
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The question looks simple: how to calculate melting points, for pure elemental metals.
Looking at the carbon group of the periodic system, ($\ce C, Si, Ge, Sn, Pb)$ the melting point (sublimation point cor carbon) starts as high as 3600°C, going quickly down to 1400° for $Si$, to 900° and down to 230° for $Sn$ then raising up to 330° for $Pb$.
Any way to get that from calculations? (And for other groups?).
1 answer
Mendeleev drew a best-fit line along each group to estimate the values in the gaps.
Here's what I was able to construct (n = row number; for example in Group 18 He = 1, Xe = 2, ... )
Some materials (famously, Mercury, Gallium) are way off predictions because of relativistic effects.
Group #, Melting Point (C)
- 1 : y = (-80/(n-3) - 259 ( only valid for n >=3)
- 2 : y = (-80/(n-4)) +1287 ( only valid for n >= 4)
- 3 : y =70 (n-1) + 1500
- 4 : y = 200 ( n - 1 ) + 1670
- 5 : y = 530 ( n -1 ) + 1900
- 6 : y = 750 (n - 1) +1900
- 7 : y = 1000 ( n - 1) + 1100
- 8 : y = 900 ( n - 1) + 1500
- 9 : y = 450 ( n -1) + 1495
- 10: y = 150 (n-1) +1450
- 11: y = 1083
- 12: y = (-100) (n-1)+400
- 13: y = 120 (n-4) + 156
- 14: y = -800 ( n - 1) +3500
- 15: y = 120 ( n - 1) - 210
- 16: y = 120 ( n - 1) - 218
- 17: y = 120 ( n - 1 ) -219
- 18: y = 50 ( n - 1) -272
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