6.3 Covalent bonding (ESABT)

The nature of the covalent bond (ESABU)

Covalent bonding occurs between the atoms of non-metals. The outera lot of orbitals of the atoms overlap so that unpaired electrons in each of the bonding atoms can be common. By overlapping orbitals, the outer energy shells of all the bonding atoms are filled. The mutual electrons move in the orbitals around both atoms. As they relocate, tright here is an attraction in between these negatively charged electrons and the positively charged nuclei. This attrenergetic pressure holds the atoms together in a covalent bond.

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Covalent bond

Covalent bonding is a kind of chemical bonding wright here pairs of electrons are shared between atoms.

You will have actually noticed in Table 6.1 that the number of electrons that are involved in bonding varies in between atoms.


There is a connection between the valency of an facet and its place on the periodic table. For the aspects in teams 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 shift steels, the valency deserve to vary. In these instances we indicate the valency by a roguy character after the facet name, e.g. iron (III) chloride.


We deserve to say the following:

A single covalent bond is developed as soon as two electrons are common between the same 2 atoms, one electron from each atom.

A double covalent bond is created when four electrons are mutual between the exact same 2 atoms, 2 electrons from each atom.

A triple covalent bond is developed once 6 electrons are mutual between the same 2 atoms, 3 electrons from each atom.

You must likewise have actually noticed that compounds have the right to have a mixture of single, double and triple bonds and also that an atom have the right to have numerous bonds. In other words, an atom does not should share all its valence electrons via one various other atom, but have the right to share its valence electrons with several various atoms.

We say that the valency of the atoms is various.

Valency

The number of electrons in the outer shell of an atom which are able to be used to develop bonds via various other atoms.

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Below are a couple of examples. Remember that it is just the valence electrons that are connected in bonding and so as soon as diagrams are attracted to present what is happening during bonding, it is only these electrons that are displayed.

Worked instance 1: Covalent bonding


How carry out hydrogen and 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 an electron configuration of (< extNe>3 exts^23 extp^5). A hydrogen atom has just one electron and also an electron configuration of (1 exts^1).


Determine how many kind of of the electrons are paired or unpaired

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


Work out just how the electrons are shared

The hydrogen atom needs an additional electron to finish its outerthe majority of energy level. The chlorine atom likewise demands an additional electron to finish its outermany energy level. Because of this one pair of electrons must be common in between the two atoms. A single covalent bond will certainly be created.

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Worked example 2: Covalent bonding involving multiple bonds


How execute nitrogen and hydrogen atoms bond to develop a molecule of ammonia (( extNH_3))?


Give the electron configuration

A nitrogen atom has actually salso electrons, and an electron configuration of (< extHe>2 exts^22 extp^3). A hydrogen atom has just one electron, and also an electron configuration of (1 exts^1).


Give the variety of valence electrons

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


Work out just how the electrons are shared

Each hydrogen atom demands one more electron to finish its valence power shell. The nitrogen atom requirements 3 even more electrons to complete its valence energy shell. Therefore three pairs of electrons need to be common in between the four atoms associated. Three single covalent bonds will be developed.

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Worked instance 3: Covalent bonding involving a double bond


How execute 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 configuration is (< extHe>2 exts^22 extp^4).


Determine the variety of valence electrons for each atom and exactly how many type of of these electrons are paired and also unpaired.

Each oxygen atom has six valence electrons. Each atom has 2 unpaired electrons.


Work out just how the electrons are shared

Each oxygen atom needs two more electrons to complete its valence energy shell. Because of this 2 pairs of electrons need to be mutual in between the two oxygen atoms so that both outermost power levels are complete. A double bond is developed.

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Properties of covalent compounds (ESABV)

Covalent compounds have numerous properties that identify them from ionic compounds and also steels. These properties are:

The melting and boiling points of covalent compounds are primarily lower than those of ionic compounds.

Covalent compounds are generally even more flexible than ionic compounds. The molecules in covalent compounds are able to relocate roughly to some extent and deserve to sometimes slide over each other (as is the situation via graphite, which is why the lead in your pencil feels slightly slippery). In ionic compounds, all the ions are tightly hosted in location.

Covalent compounds generally are not very soluble in water, for instance plastics are covalent compounds and also many type of plastics are water resistant.

Covalent compounds primarily perform not conduct electrical power when liquified in water, for example iodine liquified in pure water does not conduct power.

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Covalent bonding


Textbook Exercise 6.2

Explain the distinction between the valence electrons and the valency of an aspect.