Metals & non metals in the Periodic Table
- The elements can be divided into two broad types: metals and non-metals
- Atoms of different elements which do not have a full outer shell of electrons, can try to achieve a full outer shell by gaining or losing electrons in chemical reactions
- Elements that react by losing electrons to form positive ions are metals
- Elements that do not form positive ions are non-metals; this includes elements that react by gaining electrons to form negative ions and Group 0 elements
- Most of the elements are metals and a small number of elements display properties of both types
- These elements are called metalloids or semi-metals
- The metallic character of the elements decreases as you move across a period on the periodic table, from left to right, and it increases as you move down a group
- This trend occurs due to atoms more readily accepting electrons to fill their valence shells
Examiner Tip
An ion is an atom or molecule which has become charged through the loss or gain of one or more electron(s).
Metals will form positive ions when they react – when they lose electrons, the atom ends up with more positively charged protons than negatively charged electrons, which leaves it with an overall positive charge.
Non-metals will form negative ions when they react – when they gain electrons, the atom ends up with more negatively charged electrons than positively charged protons, which leaves it with an overall negative charge.
Positive ions are called cations and negative ions are called anions.
