伯正碳离子 primary carbocation (1ºR+)
仲正碳离子 secondary carbocation (2ºR+)
叔正碳离子 tertiary carbocation (3ºR+)

http://www.chemguide.co.uk/mechanisms/eladd/carbonium.html
CARBOCATIONS (or CARBONIUM IONS)

All carbocations (previously known as carbonium ions) carry a positive charge on a carbon atom. The name tells you that - a cation is a positive ion, and the "carbo" bit refers to a carbon atom. However there are important differences in the structures of various types of carbocations.

Primary carbocations

In a primary (1°) carbocation, the carbon which carries the positive charge is only attached to one other alkyl group.

http://www.britannica.com/eb/article-9020266/carbonium-ion
carbonium ion

any member of a class of organic molecules with positive charges localized at a carbon atom. Certain carbonium ions can be prepared in such a way that they are stable enough for study; more frequently they are only short-lived forms (intermediates) occurring during chemical reactions.

http://www.hoodong.com/wiki/正碳离子
正碳离子
carbonium ion
带有正电荷的含碳离子。一类重要的活性中间体。可用
R3C+表示（R为烷基）。

http://auntyellow.yculblog.com/post.200263.html
1901年至2000年诺贝尔化学奖获得者(四)
1994年
(美)G.奥拉(George Andrew Olah, 1927- )(出生于匈牙利)，在超强酸的作用下首次得到正碳离子，过去化学家只是用正碳离子来解释一些有机反应的机理，而正碳离子的发现为这样的机理提供了直接证据。