Table 2.

Data Sources for SMACT

Data Type	Source
Abundance	estimated crustal abundance of elements from the CRC Handbook of Physics and Chemistry53
Atomic mass	NIST Standard Reference Database 144;54 where the relative abundance of isotopes was unknown or a range of values was provided, a simple mean was taken
Covalent radius	scientific paper55
Electron affinity	scientific paper;56 no default value was used for elements that lack data on electron affinity
Eigenvalues	highest occupied p-state and s-state eigenvalues were tabulated by Harrison57 from the approximate Hartree-Fock calculations of Herman and Skillman58
HHI	elemental Herfindahl-Hirschman Index calculated from geological and geopolitical data33
Ionization potential	NIST Atomic Spectra Database59
Pauling electronegativity	updated values of electronegativity on Pauling's scale were compiled in the CRC Handbook;53 for elements 95 (Am) and above, Pauling's recommended value of 1.3 was used;60 the value for krypton (3.0) was derived from the bond energy of KrF2 and reported in a scientific paper61
SSE	“solid-state energy” model of semiconductors and dielectrics29, 30
SSE (Pauling)	extended estimates of solid-state energy from the correlation between known values and Pauling electronegativity30

Where possible, values recommended by the National Institute of Standards and Technology (NIST) were used.