Chemical bonds form when the valence electron of one atom communicate with the valence electron of one more atom.
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Since the valence electrons room the outermost electrons, they have actually the best opportunity to communicate with the valence electrons of other atoms.
Therefore, the valence electrons have actually the most influence in forming bonds.
The variety of electrons in an atom"s outermost valence shell governs the bonding behaviour.
Therefore, we group elements whose atoms have the same number of valence electrons with each other in the routine Table.
An atom through a noble gas construction (corresponding come an electron configuration #"s"^2"p"^6#) tends to be chemically unreactive.
It walk not tend to get involved in bonding.
As a basic rule, a main Group element — an facet in any kind of of groups 1, 2, and 13 to 17 — has tendency to react to acquire a noble gas electron configuration: #"s"^2"p"^6#.
Hydrogen and helium room exceptions.
This propensity is called the octet rule, since the bonded atom share eight valence electrons.
The most reactive sort of metallic facet is an steel from group 1 — one alkali metal (such as salt or potassium).
Such one atom has only a solitary valence electron.
This one valence electron is quickly lost to type a optimistic ion (cation) through a noble gas construction (e.g., #"Na"^+# or #"K"^+#).
A steel from team 2 (e.g., magnesium) is somewhat less reactive, because each atom must shed two valence electron to kind a positive ion v a noble gas configuration (e.g., #"Mg"^(2+)#).
An atom that a nonmetal has tendency to attract additional valence electrons to achieve a noble gas configuration.
One method to carry out this is to eliminate electrons from an additional atom.
The many reactive sort of nonmetal facet is a halogen such together fluorine (#"F"#) or chlorine (#"Cl"#).
Such an atom has actually the electron configuration #"s"^2"p"^5#.
It requires just one additional valence electron to accomplish a noble gas configuration.
Thus, atoms in groups 1 and also 2 tend to react with atoms in teams 16 and also 17 to form ionic compounds.
The 2 ions are attracted come each various other by electrostatic forces.
These attractions are dubbed IONIC BONDS.
Atoms generally kind ionic bonds once the electronegativity difference between the two elements is big (1.7 or greater).
An atom the a noble gas construction can likewise attain a noble gas construction by sharing share electrons with a surrounding atom.
By sharing their outermost (valence) electrons, atoms have the right to fill up their external electron shells and also gain security by gaining an octet that electrons.
Nonmetals readily form covalent bonds with various other nonmetals.
If the 2 atoms space identical, together in #"H—H"# or #"F—F"#, the electron are shared equally, and also there is no separation of confident and an adverse charges.
If the electronegativity difference in between the two aspects is very little (0.4 or less), the electrons room shared practically equally. We say the such a shortcut is NONPOLAR.
It is simply a COVALENT BOND.
To kind a covalent bond between, say, #"H"# and also #"F"#, one electron from the #"H"# and also one electron from the #"F"# kind a mutual pair.
For example, in the molecule #"H—F"#, the dash to represent a mutual pair the valence electrons, one native #"H"# and one indigenous #"F"#.
In this bond, the #"F"# atom “wants” the electrons an ext than the #"H"# does, but the #"H"# won’t give up that electron completely.
It’s a case of unlike sharing.
The electron spend more of their time close to the #"F"# atom.
This accumulation of electron density around the #"F"# provides it a slight an unfavorable charge.
The ns of electron density around the #"H"# offers the #"H"# atom a slight optimistic charge.
The bond has a confident end and also a an adverse end (or pole).
If the electronegativity difference is between 0.4 and 1.7, the link is polar covalent.
We say that this is a POLAR COVALENT BOND.
When two metal atoms re-superstructure electrons, we get a METALLIC BOND.
Unlike a covalent bond, in i m sorry valence electrons room shared between two atoms, the valence electrons in a metallic shortcut are mutual among every one of the steel atoms in the sample.
We visualize steels as variety of atom cores (nuclei and also inner electrons) or metal cations immersed in a “sea” of neighboring valence electrons.
Thus, the valence electron are complimentary to move around and are not associated with any details metal atom.
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Thus, the nature that the valence electron determines whether we get, covalent, polar covalent, ionic, or metallic bonding.