6.3 Covalent bonding (ESABT)

The nature the the covalent bond (ESABU)

Covalent bonding occurs in between the atoms of non-metals. The outermost orbitals the the atoms overlap so that unpaired electron in each of the bonding atoms deserve to be shared. Through overlapping orbitals, the outer power shells of every the bonding atoms are filled. The common electrons relocate in the orbitals around both atoms. As they move, there is an attraction in between these negatively charged electrons and the positively charged nuclei. This attractive force holds the atoms with each other in a covalent bond.

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Covalent bond

Covalent bonding is a type of chemical bonding whereby pairs the electrons are shared in between atoms.

You will have noticed in Table 6.1 the the variety of electrons that are affiliated in bonding varies between atoms.


There is a relationship in between the valency of one element and its position on the routine table. Because that the aspects in groups 1 and also 2, the valency is the group number. For the aspects in groups 13–18, the valency is the group number minus 10. For the transition metals, the valency have the right to vary. In these instances we suggest the valency by a roman character after the element name, e.g. Iron (III) chloride.


We can say the following:

A single covalent link is created when 2 electrons are shared in between the exact same two atoms, one electron from each atom.

A double covalent bond is created when 4 electrons space shared in between the same two atoms, 2 electrons from each atom.

A triple covalent shortcut is created when six electrons space shared between the same two atoms, 3 electrons from every atom.

You should also have noticed the compounds have the right to have a mixture of single, double and triple bonds and also that one atom can have several bonds. In various other words, one atom go not have to share all its valence electrons with one various other atom, yet can re-publishing its valence electrons v several different atoms.

We say that the valency that the atoms is different.

Valency

The variety of electrons in the external shell of an atom which room able come be used to kind bonds with other atoms.

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Below space a couple of examples. Remember the it is only the valence electrons that are connected in bonding and so when diagrams are attracted to display what is happening throughout bonding, it is only these electrons that space shown.

Worked instance 1: Covalent bonding


How carry out hydrogen and also chlorine atoms bond covalently in a molecule of hydrogen chloride?


Determine the electron configuration of each of the bonding atoms

A chlorine atom has actually 17 electrons and also an electron configuration of \(<\textNe>3\texts^23\textp^5\). A hydrogen atom has actually only one electron and also an electron construction of \(1\texts^1\).


Determine how many of the electrons space paired or unpaired

Chlorine has actually seven valence electrons. One of these electron is unpaired. Hydrogen has one valence electron and also it is unpaired.


Work out how the electrons space shared

The hydrogen atom requirements one much more electron to complete its outermost power level. The chlorine atom additionally needs one more electron to complete its outermost energy level. Because of this one pair that electrons need to be shared in between the 2 atoms. A solitary covalent bond will be formed.

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Worked example 2: Covalent bonding entailing multiple bonds


How carry out nitrogen and hydrogen atoms bond to kind a molecule that ammonia \((\textNH_3)\)?


Give the electron configuration

A nitrogen atom has seven electrons, and also an electron configuration of \(<\textHe>2\texts^22\textp^3\). A hydrogen atom has actually only one electron, and an electron configuration of \(1\texts^1\).


Give the number of valence electrons

Nitrogen has 5 valence electrons. Three of these electrons are unpaired. Hydrogen has actually one valence electron and it is unpaired.


Work out exactly how the electrons room shared

Each hydrogen atom demands one an ext electron to finish its valence power shell. The nitrogen atom demands three an ext electrons to finish its valence power shell. Therefore three pairs of electrons should be shared in between the 4 atoms involved. Three solitary covalent bonds will be formed.

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Worked instance 3: Covalent bonding including a double bond


How carry out oxygen atoms bond covalently to form an oxygen molecule?


Determine the electron configuration of the bonding atoms.

Each oxygen atom has eight electrons, and also their electron construction is \(<\textHe>2\texts^22\textp^4\).


Determine the number of valence electrons for each atom and how countless of these electrons room paired and unpaired.

Each oxygen atom has six valence electrons. Every atom has actually two unpaired electrons.


Work out how the electrons are shared

Each oxygen atom requirements two an ext electrons to complete its valence power shell. Because of this two bag of electrons have to be shared between the 2 oxygen atoms so that both outermost power levels space full. A twin bond is formed.

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Properties of covalent link (ESABV)

Covalent compounds have several properties that differentiate them native ionic compounds and metals. This properties are:

The melting and boiling points of covalent compound are typically lower than those that ionic compounds.

Covalent compounds room generally much more flexible 보다 ionic compounds. The molecule in covalent compounds room able to move around to part extent and also can sometimes slide over each various other (as is the situation with graphite, which is why the command in her pencil feels slightly slippery). In ionic compounds, all the ions space tightly organized in place.

Covalent compounds normally are not an extremely soluble in water, for example plastics space covalent compounds and many plastics are water resistant.

Covalent compounds typically do not conduct electrical energy when dissolved in water, for example iodine dissolved in pure water does not conduct electricity.

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Covalent bonding


Textbook exercise 6.2

Explain the difference between the valence electrons and the valency of one element.