CHEMICAL BONDING. A force that holds two atoms together is known as a Chemical Bond . The bond occurs when two nuclei attract the same electrons. Bonding is when a chemical bond is formed. When chemical bonds are broken and new bonds formed, this is a Chemical Reaction . Valence: Outer.
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These six elements form only very few bonds.
What similarities do they have?
Consider their valence energy levels.
There is something special about having eight electrons in the valence energy level. It is called an OCTET.
All of the Noble gases are chemically inactive (inert) because the valence energy level is stable.
All of the other elements have between one and seven valence electrons. All of the other elements will react in order to get an octet.
This can occur by either by the transfer of electron or by the sharing of electrons.
Ionic bonding is a transfer of electrons from one atom to another.
Most elements that lose electrons are metals.
Most elements that gain electrons are nonmetals.
Ionic bonds are formed between a metal and a nonmetal.
The metal loses electrons and becomes positive. The nonmetal gains electrons and becomes negative.
The positive ion attracts the negative ion… and they BOND. An IONIC BOND!!
Let’s look at a typical metal
Potassium’s valence shell is the fourth energy level. If potassium lost an electron, then the third energy level would be the valence or outermost level.
Now the valence shell only has 8 electrons in it. By losing an electron, the K atom has become a positive ion, a cation.
Now let’s look at a typical nonmetal
Chlorines valence shell is the third.
If Cl is to have a stable octet, it must gain one more electron.
By gaining another electron, the Cl atom has become a negative ion, an anion.
The Plot Begins To Unfold
K needs to get rid of one electron:
Cl needs to accept one electron:
The results are a positive K ion, a CATION, and a negative Cl ion, and ANION.
The potassium gives the chlorine an electron and…
The cation attracts the anion and….
….an ionic bond is formed.
The compound Potassium chloride.
In some cases more than one electron must be transferred in order to give all the atoms a complete valence energy level. For instance, when magnesium bonds to fluorine.
Magnesium 1s2 2s2 2p63s2
Fluorine 1s2 2s2 2p5
Magnesium can give fluorine one electron to give it a complete octet, but then magnesium is
1s2 2s2 2p61s2 2s2 2p63s1
So, Magnesium can give an electron to another fluorine. Now it has a complete octet in the second energy level.
1s2 2s2 2p6
Mg+2 + F-1 + F-1
This type of bonding can be easily demonstrated with electron dot structures.
7 elements naturally bond in pairs. These can be easily shown with electron dot structures.
Hydrogen is first, it shares its one electron with another hydrogen atom to form the diatomic H2. Any hydrogen gas found in nature is H2.
Notice how the elements of column VII share electrons to get an octet.
Oxygen has a double bond, the oxygen you breath is O2.
Nitrogen in the air has a triple bond, sharing 6 electrons.
There are 2 ways to remember the diatomic elements:
ClIF H. BrON is the name of the person who discovered the diatomics. Not really, but the letters in his name are the symbols of the diatomic elements.
Cl - chlorine
I - iodine
F - fluorine
H - hydrogen
Br - bromine
O - oxygen
N - nitrogen
The other way to remember the diatomic elements is the number 7. There are 7 diatomic elements and they kind of form a 7 on the periodic table.
HN O F
Typically when two atoms share electrons, one electron comes from one atom and one electron comes from the other atom.
But in a coordinate covalent bond, both electrons in the bond come from one atom.