40.THE PERIODIC TABLE – Non-metals and Metalloids.

In our last post we discussed the properties of metals in detail.In this post, let us look into  non-metals and metalloids.Let us figure out, how these two can be differentiated from metals. Let us begin our discourse on the remaining elements of the periodic table.

401

Non-metals are elements, which are found in nature, which do NOT show properties like metals. They have strikingly different properties than the metals and this is mainly due to their electronic structure.! 17 elements are classified as non metals -Hydrogen,helium, bromine,noble gases,fluorine,chlorine,nitrogen,oxygen,carbon,phosphorous,sulphur,iodine,selenium.

Properties of Non -metals –

1)They generally have 4-8 electrons in their valence shell.Thus, they have high ionization energies i.e energy required to remove the valence electron to form a cation.Non metals, therefore, gain or share electrons.They thus form anions in ionic reactions.

2)They can be solid,liquid or gaseous at room temperature.
e.g.- Solid-  Carbon ,Sulphur
Liquid – Bromine
Gas –  Chlorine,Oxygen,All noble gases (Helium,Argon,Neon,Xenon etc)

3)They don’t have metallic lustre. Most of them,which are solids , are dull in appearance .

4)They are poor conductors of heat and electricity.This is due to lack of the free electrons in their structure.Thus, they act as good insulators of heat and electricity.

5)Solid non metals are brittle .Thus, they are not ductile or malleable.

6)Non metals have high electronegativity i.e they have the ability to pull electrons more towards themselves in a chemical bond.

7)Non metals are good oxidizing agents.For a substance to be oxidizing agent it should itself get reduced i.e it should readily accept electrons.Non metals are good at gaining electrons.

e.g.Cl2 + 2e → 2Cl.

8)They form acidic oxides unlike metals. Nonmetal oxides react with water to form acids.

e.g.- CO2 + H2O → H2CO3.
SO3 + H2O → H2SO4.

402

Metalloids are elements which show properties intermediate between metals and nonmetals.Most of them have metallic lustre but are brittle like non metals.Some of them are ductile.They don’t transmit electricity at room temperatures but when heated they act as conductors.They are placed between metals and non metals in the periodic table.

Now that we have a fair idea about the different types of elements in the periodic table , we can proceed further to talk about their electronic configurations,properties and the periodicity associated with them.In the upcoming posts , we shall learn more about the periodic nature of the properties of these elements. Till then,

Be a perpetual student of life and keep learning..

Good Day !

 

References and further reading –

1)http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/metal.html
2)https://en.wikipedia.org/wiki/Metalloid

Image Source –

1)http://images-of-elements.com/carbon.php
2)https://upload.wikimedia.org/wikipedia/commons/thumb/4/44/Sulfur-sample.jpg/1920px-Sulfur-sample.jpg
3)http://bromine.yolasite.com/facts.php
4)www.smart-elements.com

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s