الباب الثاني لغات شرح مراجعة د/ عاطف

[عاطف خليفة]

* 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.