atom
/ˈætəm/noun
1- the smallest particle of a chemical element that can exist原子。
1.1
- （一般作 the atom）such particles as a source of nuclear energy原子能; 核能：
the power of the atom.
原子能。
1.2
- usu. with negative an extremely small amount of a thing or quality微量：
I shall not have one atom of strength left.
我一定会竭尽全力。
1.3
- usu. as modifier Canadian a level of amateur sport, typically involving children aged between nine and eleven〈加拿大〉原级（尤指由9-11岁儿童参加的业余运动级别）：
eight atom hockey teams.
八支原级曲棍球队。
Atoms consist of a tiny, dense, positively charged nucleus made of neutrons and protons, surrounded by a cloud of negatively charged electrons, roughly 10-8 cm in diameter. Each chemical element consists of atoms with a characteristic number of protons. Atoms are held together in molecules by the sharing of electrons.
词源
late 15th cent.: from Old French atome, via Latin from Greek atomos 'indivisible'， based on a- 'not' + temnein 'to cut'.