Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the number of electrons that a nucleus can bind   We review some results on the ionization conjecture, which says that a
neutral atom can bind at most one or two extra electrons.

3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom