Once you've got that, you can do minus 7 times a vector Just take the vector, multiply it by Pi and flip it over.

明白这点之后,你就可以计算-7乘以矢量,只需用 π 去乘以那个矢量,然后将其方向调转

耶鲁公开课 - 基础物理课程节选

If you flip the Periodic Table over you will have the ionization energy of sodium, first ionization energy, 5eV and it is about 5 eV which, when you convert, 496kJ/mol is a whopping 496 kilojoules per mole.

如果浏览周期表,你可以得到钠的离子化能，第一电离能，大约，当你转换的时候，是巨大的。

麻省理工公开课 - 固态化学导论课程节选