Smallest particle of an element which cannot be chemically divided any further. The elements differ
by their atomic structure. Atoms are inconceivably small. A normal drop
of water contains about 6,000 quintillion (a 6 with 21 zeros) atoms.
The diameter of an atom consisting of a nucleus and orbiting electrons
amounts to approx. one hundred millionth of a centimetre (10-8 cm). The nucleus is made up of positively charged protons and electrically neutral neutrons. It therefore
has a positive charge. Its diameter amounts to some ten trillionths
of a centimetre (1 to 5 · 10-13 cm). The nucleus is
therefore 100,000 times smaller than the surrounding sheath of orbiting
negatively charged electrons which are
as many as the protons in the nucleus. Atoms therefore behave electrically
neutral to the outside. See 'nuclide'.
11 - 15 March 2018
30 September - 04 October 2018
Prague, Czech Republic