This study presents a computer programmable, thermodynamically consistent representation of the second virial coefficient B, viscosity η, self-diffusion coefficient D, and isotopic thermal diffusion factor α0 of the eleven gases: N2, O2, NO, CO, N2O, CO2, CH4, CF4, SF6, C2H4, and C2H6, all at low density. Limited thermodynamic consistency is achieved by the use of four scaling parameters (σ, ε, V*0, ρ*) in addition to the molecular weight. In terms of these parameters, the collision integrals for the transport properties obey a single law of corresponding states. Furthermore, Ω(2,2)* (T) is the same as that for the universal correlation of the monatomic gases [J. Chem. Phys. Ref. Data 13, 229 (1984)] whereas Ω(1,1)* (T) is only slightly modified. The same parameters nearly correlate the spherical part B0(T)=B(T)−Bns(T) of the second virial coefficient corrected for the most important nonspherical influences; its dimensionless form B*0(T) differs from that for the monatomic gases and also, somewhat, for each of the eleven gases, except that one form suffices for N2, O2, NO, CO. The correlations embrace the reduced temperature range 1<T*<10 with the parameters σ and ε, and the range T*>10 with the parameters V*0 and ρ* derived from high-energy beam experiments. The accuracy achieved is carefully specified, and