She hopes a unique identity number may change that.

VOA: standard.2009.09.24

This means you can vary the neutron number without changing chemical identity, because chemical identity is fixed by the proton.

这表示你可以改变中子数,而不会改变它的化学特性，因为化学特性是由质子决定的。

麻省理工公开课 - 固态化学导论课程节选

The unique number will be put on an identity card which will have biometric authentication, such as fingerprints and photographs.

VOA: standard.2009.09.24