Monatomic nickel

Ni (g). Jones, Langmuir, and Mackay1 calculated the heat of sublimation of nickel to be —89.4 Millar1 calculated the value —88.2 we have estimated the value —85.0. The energy states of gaseous monatomic nickel are evaluated from the data of Russell,6 Menzies,4 and Shenstone.2... 

Many metals and noble gases, which are monatomic, form crystals with hep or cep structures. For example, magnesium, titanium, and zinc crystallize with their atoms in a hep array, while aluminum, nickel, and silver crystallize in the cep arrangement. All solid noble gases have the cep structure except helium, which crystallizes in the hep structure. It is natural to ask why a series of related substances, such as the transition metals or the noble gases, would form different crystal structures. The answer... 

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