1.
First element of the periodic table
2.
Found in our bones, number 20 of periodic table
3.
An alkali metal in group 1, period 3 periodic table
4.
A gas we breathe from the air, group 16, period 2 of periodic table
5.
A noble gas with atomic mass 39.9
6.
A vertical column on periodic table
7.
A horizontal row on the periodic table
8.
maximum number of electrons in second electron shell
9.
simplified atomic structure by Niels Bohr
10.
atomic model proposed by JJ Thomson in 1904
11.
The branch of science relative to atoms
