Investigating Covalent Bonds

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Investigating Covalent Bonds

Covalent bonds are formed when atoms share electrons, one from each

atom in a single bond, to form electron pairs, usually making their

outermost shells up to eight electrons by this means. This would make

them more stable, less reactive and an electronic structure like a

noble gas.

They are most frequently formed between pairs of non-metallic

elements. Non-metallic elements usually have from four to eight

electrons in their outermost shells, the so-called valency electrons,

which are used for chemical bonding. In any given “full” shell of

eight electrons, the electrons occur in four pairs, but in incomplete

shells, the electrons exist singly where possible.

Sometimes, atoms of elements form covalent bonds with other atoms of

the same element. Thus two chlorine atoms form the chlorine molecule,

Cl2, by sharing their unpaired electrons. In the case of oxygen (O2),

there are two unpaired valency electrons in each atom, so that two

electron-pair bonds are formed between the two atoms to complete their

octet of electrons, a double bond.

Covalent bonds can also be formed in such a way as to form a giant

molecule, such as happens in diamond. Here, each of the four valency

electrons of a carbon atom is shared with one of the valency electrons

of another carbon atom, so that every carbon atom in the structure has

four different carbon atoms bonded to it.

In simple molecules, the molecules are held together by strong

covalent bonds, but the bonds between different molecules are

relatively weak, and therefore easily broken. Many compounds

containing covalent bonds, therefore, are liquids or gases a...

... middle of paper ...

...ated with ionic compounds means that much energy

is required to break these bonds.

They are soluble in water. This is because water is a so-called

ionizing solvent, because of its polar nature. The water molecule is

capable of attaching itself to both positive and negative ions, water

is therefore capable of carrying away the ions into solution (in the

form of "hydrated" ions), so that the solid eventually dissolves.

Non-polar solvents do not dissolve ionic solids.

Compounds containing ionic bonds also conduct electricity when in

solution (water) or when molten. This is because both the solution and

the molten compound contain ions that can move about when an electric

current is passed through. Solid ionic compound cannot conduct

electricity as the ions are held in their rigid lattice, and are not

free to move.

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