Chemistry is all about atoms,molecules and reaction among each other. But why a single atom react to form molecules? Its simple answer lies in the atomic structure.
What is Atom
Atom is a smallest particle of matter which can not freely exit but can participate in chemical reactions individually.Atom made up of three fundamental particle namely- Electron,Proton and Neutron.
What is Element
Material which is composed of only one type of atom or group of atoms are called elements.
Example
Gold ring made up of 24 carat gold. Means the whole ring is made up of a single type of atoms.
Diamond in necklace,the whole diamond is made up of a single type of element called carbon.
STRUCTURE OF ATOM
According to Bohr Atomic model, a small positively charged nucleus is surrounded by revolving negatively charged electrons in fixed orbits. He concluded that electron will have more energy if it is located away from the nucleus whereas the electrons will have less energy if it located near the nucleus.
Everything is start with the electrons in outer most shell or valance shell.
Okay we learnt the structure enough.
Why do they react to each other??
They react to each other because of their electronic configuration(how electrons are arrange in atom). Every atom try to attain duplet and octet in their outer most shell.
Atoms which contains less than 4 electrons in their outermost can easily give their valance electron and become octate and atom which contain 6 or more than 6 can take those electron and become octate.
Those who lose electron easily are called as electropositive element and can be classified as Metals.
The outermost orbit of an atom has less then 4 electrons,the material is generally consider as metals.
The elements which have more than 4 electrons in their valance shell are called as Non-metal.
They do not easily give the electrons or they take electrons from other elements and become negative ions,generally called as electronegative elements.
The atoms react after transfer of electron and gain of electron,this process is called ionic or electrovalent bond.Their is another kind of bond formation called covalent bond that is done by sharing of equal no. of electrons.
Those kind of bond formation is done by atoms which have 4 or 5 electrons in their outer or valance shell.
When the outermost orbit of an atom has less then 4 electrons,the material is generally a?
These elements are called metals. They can easily loose electrons so they are considered as electropositive elements.
According to Bohr's atom model 2N^2 rule first shell contain 2 electron(maximum) second shell contain 8 electron(maximum) and third shell contains 18 electrons(maximum),so for atomic number 17 their is configuration = 2,8,7 last shell contains 7 means this element will lie in 17th group (halogen) and also known as chlorine .
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