What do adamantanium, vibranium and unobtainium In the same period have in common?

frequency, z, and the collision density, z, in carbon dioxide (co2), r 180 pm at 30 °c and 120 kpa

5 structural isomers

the isomers are:

n-exane :   ch3ch2ch2ch2ch2ch3

2-methylpentane :   ch3ch(ch3)ch2ch2ch3

3-methylpentane :   ch3ch2ch(ch3)ch2ch3

2,3-dimethylbutane :   (ch3)2chch(ch3)2

2,2-dimethylbutane :   (ch3)3cch2ch3