* 5- Metallic and non metallic property
* Metals
Their valence shell has less than half its capacity
They are electropositive elements because they lose electrons and become positive ions(cations)Their valence electrons can move from one position to another in the atom so they conduct electricityThey have large atomic radii - but small ionization energy and small electron affinity.
Example
Na 1S2 2S2 2p6 3S1
* Non - Metals
Their valence shell has more than half its capacity .They are electronegative elements because they gain electrons and they become negative ions ( anions ) .Their valence electrons can’t move so they don’t conduct electricity .They have small atomic radii - but big ionization energy and big electron affinity
Example
Cl 1S2 2S2 2P6 3S2 3P5
* Metalloids
Their valence shell half filled
Their properties intermediate between metals, and non metals
Metalloids can unite with metals or none metals.
They conduct electricity less than metals but more than non - metals.
They are used as semiconductors in electronic instruments
Example
14Si 1S2 2S2 2P2 3S2 3P2
* Trends of the propety
a) In periods
The period begins with the highest metallic character then the metallic properties decrease as the atomic number increase, and non metallic properties increase.The highest metallic character in the left side while the highest non - metallic properties in the right side
Metalloids are found in the middle.
b) In groups
The highest non-metallic properties are found at the top in the right side and decrease as we go down.
The group in the left begins with metallic properties and increase as we move down.