When we talk about covalent bonds refer to a specific type of binding between atoms in which they are shared pairs of electrons. They usually present a stable balance between each element and It allows atoms to find stability in their electronic configuration.
What are they?
It’s a type of chemical binding that is characterized by the sharing of pairs of electrons between different atoms, whether non-metal, semi-metal or hydrogen.
According to the theory of the octet, the atoms of the elements reach the stability when reaching the configuration electronics of noble gases, i.e. when they have eight electrons in your outer layer or two if you only have one layer.
The Atoms of the elements that form covalent bonds have a tendency to win electrons to achieve stability.
For a covalent link to be given necessary:
- That there’s a little one. difference of electronegativity between the atoms united, usually minor to 1,7.
- The atoms that join They need to win electrons, neither one will be willing to give in.
- These unions occur between no metals, not metals and hydrogen, hydrogen hydrogen.
Characteristics of covalent bonds
Among the basic characteristics of the Covalent bonds we can mention:
- They are considered strong joints that occur in non-metallic atoms. It occurs in those who have a similar electronegativity or with a difference of less than 1.7.
- They require less energy than the ion links to break.
- These links are applied to these links the rule of the octet, which allows determine how many electrons are shared to reach the equilibrium state or 8 electrons in the valence layer.
- Covalent bonds are not egalitarian, if an atom has greater electronegativity than the other will form a polar covalent bond. Yes, the electronegativity is similar to form non-polar covalent bonds. I just know. They reach egalitarian covalent bonds when the two atoms are identical.
- They are in the form of liquid or soda substances known as substances The low-key, which, doesn’t drive electricity very well, have lows boiling and melting points.
Covalent bond types
Covalent bonds depend on the difference of electronegatives between the atoms that make it up. This defines the type of covalent link that can be formed:
According to the difference in electronegativity the covalent links may be:
Covalent non-polar bond
They are the ones that occur when the difference in electronegativity between Atoms are less than or equal to 0.4. The electrons are similar or the same. If the affinity between the two electrons is high, the attraction will be – Strong.
It sues. occur in gases or diatomic elements. They’re important for biology because they form oxygen and peptide bonds of amino acid chains.
Covalent bond polar
I know when the difference in electronegativity is 0.4 to 1.7 and the electrons are shared irregularly. The element with Greater electronegativity will strongly attract the electrons that form the junction.
This gives rise to a molecule with one side positive (minor electronegativity) and a negative side. It’ll be a molecule with electrostatic potential, so you can join other polar elements.
The Most common polar bonds are those that occur with hydrogen and More electronegative atoms.
According to pairs of electrons involved in the link we can have the following covalent links:
Links are given that share only a couple of electrons, each atom involved provides only one electron. It’s a weak union and involves a sigma link. (i.). It is represented as follows:
Two. pairs of electrons are shared between atoms, that is, we will find four electrons between the two elements. Involve a sigma link and a pi link (a) is represented as follows:
It’s the strongest type of covalent bond, is given between atoms that share six electrons or three pairs. In this type of link we find a union sigma (-) and two pi (-). This is the case:
Quadruple links are also presented, but they are rare and occur with metal compounds such as chromium acetate (II).
Properties of covalent compounds
Covalent compounds have a series of unique properties:
- At normal temperature and atmospheric pressure they can be solid, liquids or gases.
- They’re not drivers of the electricity when they dissolve in water.
- When dissolving in water the molecules separate and remain Independents.
- They have fusion points and Low boiling.
- They’re more fuel.
- Polar compounds are not easily soluble in water.
Exceptions to the rule of the octet
There are exceptions to the rule of the eld, for example, with boron and beryllium this is not fulfilled because they have few electrons to form a The beryllium only has two valence electrons and the boron has three.
In the case of hydrogen and helium, the valence of which only admits two electrons, also This exception is presented.
Differences with the ion bonds
- Covalent links are They share pairs of electrons.
- In the ion links you are transmit or lend the electrons from one atom to another, occurs in the presence of Metal atoms.