They are kind of opposite processes. Chemical synthesis is execution of chemical reactions to make products. Like you take two substances, you put them together, they react and you have new a substance. For example.

here Sodium and Chlorine react to make a new substance which is Sodium Chloride.
Chemical decomposition is process of seperating a substance to different substances. There is a substance by a reaction this substance becomes two substances, Like : XY -> X+Y For example :
Water is water and not dirt because its from the cloud s that makes rain also air is water because it was water and then started to get hot and steamy so tired to a gas and then tired to air
The element is Sodium with an atomic number of 11 and electrovalent bonding takes place when it comes near an atom having seven valence electrons.
<h3>What is Electrovalent bonding?</h3>
This is also referred to as ionic bonding and involves the transfer of atoms of an element to another.
In order for both of them to achieve a stable octet configuration, sodium donates one atom to the element seven valence electrons.
Read more about Electrovalent bonding here brainly.com/question/1979431
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