Chemical bonds form when the valence electrons of one atom communicate with the valence electrons of one more atom.
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Since the valence electrons space the outermost electrons, they have actually the best opportunity to communicate with the valence electron of various other atoms.
Therefore, the valence electrons have actually the most influence in creating bonds.
The number of electrons in one atom"s outermost valence covering governs the bonding behaviour.
Therefore, we group facets whose atoms have actually the same variety of valence electrons with each other in the regular Table.
An atom v a noble gas construction (corresponding come an electron construction #"s"^2"p"^6#) often tends to be chemically unreactive.
It does not tend to take part in bonding.
As a general rule, a main Group element — an element in any type of of teams 1, 2, and also 13 to 17 — often tends to react to obtain a noble gas electron configuration: #"s"^2"p"^6#.
Hydrogen and helium room exceptions.
This propensity is called the octet rule, due to the fact that the bonded atoms share eight valence electrons.
The most reactive kind of metallic facet is an steel from team 1 — one alkali steel (such as salt or potassium).
Such an atom has actually only a solitary valence electron.
This one valence electron is conveniently lost to form a positive ion (cation) with a noble gas configuration (e.g., #"Na"^+# or #"K"^+#).
A steel from team 2 (e.g., magnesium) is somewhat less reactive, due to the fact that each atom must lose two valence electrons to form a positive ion v a noble gas configuration (e.g., #"Mg"^(2+)#).
An atom that a nonmetal has tendency to attract extr valence electrons to achieve a noble gas configuration.
One method to carry out this is to remove electrons from an additional atom.
The many reactive sort of nonmetal aspect is a halogen such together fluorine (#"F"#) or chlorine (#"Cl"#).
Such an atom has actually the electron configuration #"s"^2"p"^5#.
It requires only one extr valence electron to accomplish a noble gas configuration.
Thus, atoms in teams 1 and 2 tend to react with atoms in groups 16 and 17 to type ionic compounds.
The 2 ions room attracted to each other by electrostatic forces.
These attractions are dubbed IONIC BONDS.
Atoms generally kind ionic bonds once the electronegativity difference in between the two facets is big (1.7 or greater).
An atom the a noble gas configuration can also attain a noble gas construction by share share electrons with a bordering atom.
By sharing your outermost (valence) electrons, atoms deserve to fill increase their outer electron shells and also gain stability by gaining an octet of electrons.
Nonmetals readily kind covalent bond with various other nonmetals.
If the 2 atoms space identical, as in #"H—H"# or #"F—F"#, the electrons are common equally, and there is no separation of positive and negative charges.
If the electronegativity difference in between the two facets is very small (0.4 or less), the electrons are shared almost equally. Us say the such a bond is NONPOLAR.
It is merely a COVALENT BOND.
To kind a covalent bond between, say, #"H"# and #"F"#, one electron indigenous the #"H"# and also one electron from the #"F"# form a mutual pair.
For example, in the molecule #"H—F"#, the dash to represent a common pair that valence electrons, one indigenous #"H"# and also one indigenous #"F"#.
In this bond, the #"F"# atom “wants” the electrons an ext than the #"H"# does, yet the #"H"# won’t provide up its electron completely.
It’s a case of unlike sharing.
The electrons spend much more of their time near the #"F"# atom.
This accumulation of electron density roughly the #"F"# offers it a slight an adverse charge.
The lose of electron density roughly the #"H"# offers the #"H"# atom a slight optimistic charge.
The bond has actually a optimistic end and a an adverse end (or pole).
If the electronegativity distinction is between 0.4 and 1.7, the shortcut is polar covalent.
We say the this is a POLAR COVALENT BOND.
When two metal atoms share electrons, we gain a METALLIC BOND.
Unlike a covalent bond, in which valence electrons space shared in between two atoms, the valence electrons in a metallic link are mutual among every one of the steel atoms in the sample.
We visualize metals as variety of atom cores (nuclei and also inner electrons) or metal cations immersed in a “sea” of neighboring valence electrons.
Thus, the valence electrons are totally free to move around and are not associated with any particular metal atom.
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Thus, the nature the the valence electrons determines whether we get, covalent, polar covalent, ionic, or metallic bonding.