The Role of Electons

~Electron Shells ~Ions ~Periosic table ~Valence electrons

Ions p.16

~Atoms are electrically neutral because the number of electrons and equal to the number of__.
~If this balance is changed, then we call the atoms charged and it's called an Ion.
~Ions form during a chemical reaction as electrons move from atoms to atom.
~If an atom loses an electron it's called an positive ion.
~if an atom gains an electron it's called negative ion.

Perodic Table

*Their is 113 elements and 8 groups in the periodic table.
*7 periods
*Dmitri is the father of the periodic table, he ordered the elements in the table

*At the bottom left it is most reactive, the bottom right is the less reactive elements


Electron Shells

Valence Electrons