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What are the causes of Chemical Bonding?

  • Last Updated : 11 Nov, 2021

Noble gases are chemically inert, and their electron arrangements are extremely stable, preventing the outermost electrons from participating in chemical reactions. In the outermost shell of an atom of a noble gas, there are eight electrons. The number of outermost electrons is just two in the case of one noble gas, helium. Since everything in the world strives to be more stable. Stability for atoms requires possessing the electron configuration of noble gases. As a result, one of the most common reasons for chemical bonding is this. The formation of positive and negative ions, as well as other reasons for chemical bonding, are covered further below.

Causes of Chemical Bonding

The atoms join to form the noble gas electron configuration, which makes the atoms more stable. To put it another way, atoms create chemical bonds in order to acquire stability by obtaining the inert gas electron configuration. As a result, when atoms combine to create chemical bonds, each atom receives 8 electrons in the outermost shell and 2 electrons in the K shell. As a result, all atoms in their outermost shell tend to achieve the noble gas electron configuration of 8 electrons or 2 electrons (in K shell) and become more stable. An atom can attain the noble gas electron arrangement in one of three ways

  • By losing one or more electrons to another atom.
  • By gaining one or more electrons from another atom.
  • By sharing one or more electrons with another atom.

Between metals and non-metals, chemical reactions occur in which the noble gas electron arrangement is achieved by the loss and gain of electrons between the atoms. Chemical processes that attain the noble gas electron arrangement by sharing electrons between atoms occur between non-metals and non-metals. It is vital to understand the definition of the term ‘ions’ and how they are created in order to comprehend the reactions between metals and non-metals.

What are Ions?

An electrically charged atom or collection of atoms is known as an ion. The addition of electrons to neutral atoms or molecules, or the removal of electrons from neutral atoms or molecules, produces ions. An ion is created when an atom loses or gains electrons, resulting in an uneven number of electrons or protons. Cations and anions are two different types of ions.

  • Cation- A positively charged ion is referred to as a cation. When an atom loses one or more electrons, it forms a cation. Since a cation is generated by removing electrons from an atom, a cation has fewer electrons than a normal atom or a neutral atom. The number of protons and electrons in a neutral atom is equal. Cations are the ions of all metal elements. The only cations generated from non-metals are hydrogen and ammonium. A sodium atom, for example, loses one electron to create the sodium ion, Na+, which is a cation.

Na        –          e           →              Na+
(Sodium atom)          (electron)             (Sodium-ion)

  • Anion- An anion is an ion with a negative charge. An anion is created when an atom gains one or more electrons. An anion has more electrons than a typical atom or neutral atom since it is generated by the addition of electrons to an atom. The number of protons and electrons in a neutral atom is equal. An anion contains more electrons than protons because it is created by the addition of one or more electrons to an atom. Except for hydrogen ion and ammonium ion, all non-metal ions are anions. An anion is formed when a chlorine atom gets one electron and becomes the chloride ion, Cl.

Cl              +            e                          Cl
(Chlorine atom)             (electron)              (Chloride ion)

Formation of Positive Ions

If an element’s outermost shell has 1, 2, or 3 electrons, it loses these electrons to attain the noble gas electron arrangement of 8 outermost (or valence) electrons, resulting in positively charged ions known as cations. Due to energy limitations, it is not possible to add 7, 6, or 5 electrons to an atom. Now that the metal atom has one, two, or three electrons in its outermost shell, it loses electrons to create positively charged ions or cations. Metals that transfer their outermost electrons to produce positive ions include sodium, lithium, magnesium, and potassium, among others.

A cation with unit positive charge is formed when an atom with one electron in its outermost shell loses one electron. A cation with two units of positive charge is formed when an atom loses two electrons from its outermost shell. A cation with three units of positive charge is formed when an atom loses three electrons from its outermost shell.

The formation of the sodium and magnesium ion is explained in detail further below.

  • Formation of a Sodium Ion: Sodium has an atomic number of 11. As a result, sodium’s electronic configuration is 2, 8, 1. The fact that sodium possesses one electron in its outermost shell  (M shell) is self-evident. This is not a stable electron configuration. The outermost shell of a stable arrangement normally includes 8 electrons. As a result, sodium is both unstable and reactive. The sodium atom must donate one outermost electron to another atom in order to become stable. The sodium atom gains one unit of positive charge by losing one electron, resulting in the sodium ion Na+. An electron has one unit of a negative charge, while a proton has one unit of positive charge. Since a sodium atom has the same number of electrons and protons, 11 electrons and 11 protons, it is electrically neutral and has no charge overall. There are 11 protons but only 10 electrons in the sodium ion Na+. This indicates that the sodium ion has one more proton than electrons. A sodium ion has one unit of positive charge because it contains one more proton than electrons. It is denoted as Na+. Moreover, sodium ions have the same electrical configuration as the nearest noble gas, neon.

Na               –          e           →              Na+
(Sodium atom)          (electron)             (Sodium-ion)

Elements

Sodium atom

        Na

Sodium-ion



       Na+

Neon

   Ne

Electronic configuration

K   L   M

2,  8,   1

K    L    M

2,   8

K   L  

2,   8

  • Formation of a Magnesium ion: Magnesium has an atomic number of 12. As a result, magnesium’s electrical configuration is 2, 8, 2. Magnesium has two electrons in its outermost shell, as can be seen (M shell). This is not a stable electron configuration. The outermost shell of a stable arrangement normally includes 8 electrons. As a result, magnesium isn’t extremely stable. The magnesium atom must donate its two outermost electrons to another atom in order to become stable. The magnesium atom gains two units of positive charge by losing two electrons and therefore becomes a magnesium ion. An electron has one unit of a negative charge, while a proton has one unit of positive charge. Since a magnesium atom contains the same number of electrons and protons, 12 electrons and 12 protons, it is electrically neutral and has no charge overall. There are 12 protons but only 10 electrons in magnesium ions. This indicates that the magnesium ion has two more protons than electrons. A magnesium ion has two units of positive charge since it has two more protons than electrons, and it is denoted as Mg2+. Magnesium ions also have the same electronic arrangement as the nearest noble gas, neon.

Mg                  –          2e           →              Mg2+
(Magnesium atom)          (electrons)             (Magnesium-ion)



Elements

Magnesium atom

       Mg

Magnesium ion

        Mg2+

Neon

Ne

Electronic

configuration

K   L   M

2,  8,  2

K   L   M

2,  8

K   L

2,  8

Formation of Negative Ions

If an element’s outermost shell has 5, 6, or 7 electrons, it gains electrons to obtain the noble gas electron arrangement of 8 outermost (or valence) electrons, resulting in negatively charged ions known as anions. Due to the extremely high energy required, it is impossible to remove 5, 6, or 7 electrons from an atom. Since the outermost shell of a non-metal atom normally possesses 5, 6, or 7 electrons, non-metal atoms take electrons to create negatively charged ions or anions. Non-metals that accept electrons to generate negative ions include chlorine, bromine, iodine, oxygen, and nitrogen, among others.

When an atom accepts one electron into its outermost shell, it becomes a negative-charged atom. An anion with two units of negative charge is formed when an atom takes two electrons into its outermost shell. An anion with three units of negative charge is formed when an atom accepts three electrons into its outermost shell.

The formation of the chloride and oxide ion is explained in detail further below.

  • Formation of a Chloride ion: Chlorine has an atomic number of 17. As a result, chlorine’s electronic arrangement is 2, 8, 7. The outermost shell  (M shell) of chlorine has seven electrons. This is not a stable electron configuration. The outermost shell of a stable arrangement normally includes 8 electrons. To become stable, the chlorine atom accepts one electron from another atom and obtains the noble gas configuration of argon, which is the closest noble gas configuration. The chlorine atom gains one electron and gains one unit of a negative charge, forming the chloride ion. An electron has one unit of a negative charge, while a proton has one unit of positive charge. Since a chlorine atom has the same number of electrons as protons (17 electrons and 17 protons), it is electrically neutral and has no charge overall. There are 17 protons in the chloride ion, but 18 electrons since one extra electron have been added. This indicates that the chloride ion has one extra electron than the protons. A chloride ion has one unit of negative charge since it has one more electron than protons, and it is denoted as Cl.

Cl              +            e            →             Cl
(Chlorine atom)             (electron)              (Chloride ion)

Elements

Chlorine atom

        Cl



Chloride ion

        Cl+

Argon

    Ar

Electronic 

configuration

K   L   M

2,  8,  7

K   L   M

2,  8,  8

K   L   M

2,  8,  8

  • Formation of an Oxide ion: Oxygen has an atomic number of 8. As a result, oxygen’s electronic configuration is 2, 6. The outermost shell (L shell) of oxygen has 6 electrons. This is not a stable electron configuration. The outermost shell of a stable arrangement normally includes 8 electrons. The oxygen atom accepts two electrons from another atom in order to become stable, resulting in the closest noble gas configuration of neon. An electron has one unit of a negative charge, while a proton has one unit of positive charge. The oxygen atom gains two units of negative charge by gaining two electrons, forming the oxide ion. Since an oxygen atom contains the same number of electrons and protons, 8 electrons and 8 protons, it is electrically neutral and has no charge overall. There are 8 protons in the oxide ion, yet there are 10 electrons since two extra electrons have been added. This indicates that the oxide ion has two more electrons than protons. An oxide ion has two units of negative charge since it has two more electrons than protons, and it is denoted as O2-.

O              +                 2e-             →             O2+
(Oxygen atom)             (electron)                   (Oxide ion)

Elements

Oxygen atom

         O

Oxide ion

       O2-

Neon

Ne

Electronic



configuration

K   L 

2,  6

K   L

2,  8

K   L

2,  8

Sample Questions

Question 1: Why does carbon not form ions?

Answer:

Carbon which is a non-metal has four electrons in its outermost shell. It cannot lose or gain four electrons due to energy limitations. As a result, the carbon atom does not form ions.

Question 2: Noble gases are said to be unreactive. Explain why.

Answer:

It has 2 electrons in its outermost shell (only in case of hydrogen) or 8 electrons in its outermost shell which is the capacity of these shells. Since their electron configurations are extremely stable and the outermost electrons do not participate in chemical reactions, hence noble gases are chemically unreactive.

Question 3: Which kind of ions do metals make?

Answer:

Metals have one, two, or three electrons in their outermost shell. Metals transfer their outermost electrons to produce positive ions. So metals form cations.

Question 4: What kind of ions will aluminium make?

Answer:

The atomic number of aluminium is 13. Its electronic configuration is 2, 8, 3. It has 3 electrons in its outermost shell which is not a stable state. So, it loses its outermost 3 electrons to attain the nearest noble gas configuration which is neon. Since it loses electrons, so aluminium produces positive ions or cations.

Question 5: Non-metals are said to make anions. Why?

Answer:

Non-metals have five, six, or seven electrons in their outermost shell. They accept electrons from other atoms in their outermost shell to produce negative ions. So non-metals form anions.


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