Is Magnesium chloride (MgCl2) ionic or covalent? Types of bond in MgCl2
Magnesium chloride appears as a white crystalline solid is an inorganic compound having the chemical formula MgCl2. It is made up of one magnesium and two chlorine atom and its salts are highly soluble in water. It is used in medicine for many cellular activities.
In this tutorial, we will study Is Magnesium chloride (MgCl2) is ionic or covalent? Formation of bond in MgCl2, etc.
So, Is MgCl2 ionic or covalent? MgCl2 is an ionic compound and consists of Mg2+ and 2Cl– ions which are held together by ionic bonding. The bond formed between the metal (magnesium) and nonmetal (chlorine) is ionic due to the large gap of electronegativity difference exists between them.
|Name of Molecule||Magnesium chloride|
|Molar mass||95.211 g/mol|
Why Magnesium chloride (MgCl2) is an ionic compound?
An ionic compound is a compound that is formed when the atoms lose or gain valence electrons to become more stable and form positive and negative ions.
Further, these charged ions are held by the electrostatic force of attraction, and eventually, a bond is formed between them which is called an ionic bond.
Usually, the metal atom transfers the electron whereas the nonmetal accepts the electron.
Here, in the case of the MgCl2 compound, magnesium is a metal atom that belongs to the alkali group and chlorine is a nonmetal that belongs to the p-block group.
So, magnesium metal transfers its electrons whereas chlorine atoms will accept it and a bond will form between them which is called an ionic bond.
As we see in the above figure, the magnesium metal is transferring their electrons and both chlorine as a nonmetal accepting the electrons, and both these formed Mg2+ and 2Cl– ions which are held together by the electrostatic force of attraction, and an ionic bond forms between them.
Examples of some more ionic compounds – MgO, Na2O, NaCl, etc.
How ionic bond is formed in MgCl2?
An ionic bond is formed either by giving or taking electrons.
The formation of ionic bond in MgCl2 usually take three process-
(1). Formation of cation(Mg2+)
A cation is formed when the metal atom loses its electron to obtains stability. In the case of MgCl2, the magnesium atom is a metal that belongs to group 2 in the periodic table and has an atomic number of 12.
The electronic configuration for magnesium is 1s22s22p63s2 or [2, 8, 2]. So, by losing 2 electrons, the magnesium metal electronic configuration will be [2, 8]. So, now it has an electronic configuration close to the noble gas configuration and has 8 electrons in the outermost shell.
Hence, the magnesium wants to lose 2 electrons from its outermost shell to achieve stability.
(2). Formation of the anion(2Cl–)
An anion is formed when the nonmetal gains the electrons to obtains stability. In the case of the MgCl2 compound, chlorine is a nonmetal that belongs to group 17 in the periodic table and has an atomic number of 17.
The electronic configuration for chlorine is 1s22s22p63s23p5 or [2, 8, 7]. So, by gaining 1 electron, the chlorine nonmetal electronic configuration will be [2, 8, 8]. So, now it has an electronic configuration close to the noble gas configuration and has 8 electrons in its outermost shell.
Hence, both chlorine nonmetal gains 1 electron to achieve the stable form.
(3). Electrostatic force attraction between ions(Mg2+ and 2Cl–)
Electrostatic force is non-contact force that attract the positive and negative charged particles or objects without touching them.
We know that opposite charges will always attract each other. So, the formation of ions Mg2+ and 2Cl– will attract each other because of positive and negative charges.
Therefore, both these ions are linked together by the electrostatic force of attraction and a formation of a bond occurs between them which is called an ionic bond or electrovalent bond.
Why is MgCl2 not a covalent compound?
A covalent bond is formed when sharing of electrons occurs between the atoms to achieve stability.
Usually, covalent bonds formed between the two nonmetals, between p-block and p-block, and formed when electronegativity difference between atoms exist less than 1.7.
Examples of some compounds that form covalent bonds – H2O, NH3, H2S, SO2, NO2, AlCl3, etc.
- Why does H2O form a covalent bond?
- Why does NH3 form a covalent bond?
- Why does H2S form a covalent bond?
- Why does SO2 form a covalent bond?
- Why does NO2 form a covalent bond?
- Why does AlCl3 form a covalent bond?
According to the Pauling scale of electronegativity-
- The covalent bond is formed between the two atoms when their electronegativity difference occurs less than 1.7.
- The ionic bond is formed between the two atoms when their electronegativity difference occurs more than 1.7.
Now check the electronegativity difference in MgCl2 compound-
⇒ The electronegativity value for magnesium atom = 1.31
⇒ The electronegativity value for chlorine atom = 3.16
∴ The difference in the electronegativity between magnesium and chlorine atoms = 1.85
So, the difference in electronegativity between magnesium and chlorine is more than 1.7, hence, it is large enough to make an ionic bond between them as per the Pauling scale of electronegativity.
Also, in the MgCl2 compound, there is no sharing of electrons involves, magnesium metal atom transfer its electrons, and both chlorine as nonmetal accepts the electron to achieve stability by completing the octet.
And a bond is formed between the ions which is called an ionic bond.
Energy involving in the process of ionic bond formation in MgCl2?
When a chemical bond is formed it releases energy, which helps to attain stability between the new bonds.
The formation of a bond releases the energy whereas the breaking of the bond absorbs the energy.
There are three types of energy involved in the process of ionic bond formation in MgCl2.
(a). Ionization enthalpy
(b). Electron gain enthalpy
(c). Lattice energy
⇒ Ionization enthalpy
Ionization enthalpy is the amount of energy required to remove the loose electron of an isolated gaseous atom from its outermost shell, then convert it into a gaseous positive ion.
Ionization enthalpy is always positive and occurs when an electron loses from the atom.
So, in the case of ionic bond formation in MgCl2, when an electron is loosed or released from the magnesium metal then the energy associated with it is ionization enthalpy.
⇒ Electron gain enthalpy
This energy is just opposite to ionization energy. The electron gain enthalpy is the enthalpy that occurs when an electron is added to an isolated atom in the gaseous phase, then convert this isolated atom into a gaseous negative ion.
The electron gain enthalpy may be positive or negative but most of the time it is negative.
So, in the case of ionic bond formation in MgCl2, when an electron is accepted or is added to the chlorine atom then energy associated with it is electron gain enthalpy.
⇒ Lattice energy
The lattice energy is the energy that releases when 1 mole of an ionic bond is formed from adding gaseous anion and cation.
The more the lattice energy releases during the formation of an ionic bond, the higher is the stability of that bond.
So, in the case of ionic bond formation in MgCl2, when cation(Mg2+) is attracted by anion(2Cl–), then some amount of energy is released which is called lattice energy.
As you see in the above figure when 1 mole of cation(Mg2+) diffuses with two moles of the anion(Cl–) then one mole of solid(MgCl2) is formed.
And the energy released during the formation of ionic bonds in MgCl2 is lattice energy.
Properties of Magnesium chloride
- It appears as a white crystalline solid.
- It has a boiling point of 1,412 °C and a melting point of 714 °C.
- It is soluble in water, acetone, and pyridine.
- Magnesium chloride has an octahedral coordination geometry.
- The hydrated magnesium chloride is extracted from seawater or brine.
Uses of Magnesium Chloride
- Magnesium chloride is used as a catalyst to produce polyolefins.
- It is used for de-icing the highway, sidewalks, and parking.
- It is used as a food additive.
- It is used for soil stabilization, dust control, and wind erosion as well.
- It is used in nutraceutical and pharmaceutical preparations.
Which has a more ionic character between MgCl2 or MgO?
First of all, both MgCl2 and MgO are ionic in nature because of the existence of a large electronegativity difference between the atoms of these compounds.
But no compound in the universe exists as 100% ionic. Therefore, MgO and MgCl2 have some covalent characters even they are ionic in nature.
So, which has a more ionic character? MgO has a more ionic character than MgCl2, this is because the difference of electronegativity value between Mg and O is larger than the difference of electronegativity between Mg and Cl.
Which has more covalent character MgCl2 or CaCl2?
Both calcium and magnesium belong to that same group and have the same valency with the same charge. But magnesium is present just above calcium.
As we go down the periodic group, the atom size increases. Hence, the calcium is larger than magnesium.
Going by the trick to finding more covalent characters, use the C/S ratio formula.
⇒ C = Charge of cation
⇒ S = Size of the atom
“Larger is the C/S ratio, more will be the covalent character”.
So, both calcium and magnesium have the same charge but the atomic size of calcium is larger than magnesium.
Therefore, the C/S ratio of MgCl2 is larger than the C/S ratio of CaCl2.
∴ The MgCl2 has a more covalent character than CaCl2.
Which is more ionic, MgCl2 or NaCl?
Of course, the NaCl compound is more ionic than MgCl2, one reason is that the electronegativity difference between the atoms of the NaCl compound is larger than MgCl2 atoms.
And the other reason is that Mg2+ has high polarizing power than Na+, hence, the Mg2+ drawback the bonding electrons from Cl– to a greater extent, this develop more covalent character in MgCl2.
Why does magnesium metal lose electrons and chlorine gains the electron to form an ionic bond in MgCl2?
This is because magnesium is a metal that has low ionization energy, metals are more prone to lose electrons to achieve the octet.
As magnesium metal has the electronic configuration (2, 8, 2), so, for magnesium, it is easier to lose the two-electron to achieve octet and hence, attains stability.
A nonmetal has high ionization energy and large electronegativity, they can easily accept the electrons to achieve the octet.
As chlorine nonmetal has the electronic configuration (2, 8, 7), so, gaining one electron makes its electron configuration (2, 8, 8), hence, achieve the octet and attains stability.
- Is Magnesium chloride (MgCl2) ionic or covalent? MgCl2 is an ionic compound because the bond formed between magnesium and the chlorine atom is ionic in nature, it is formed as magnesium atom loses two electrons to form Mg2+ ion and each chlorine accepts the one electron to form Cl– ion, later these ions(Mg2+ and 2Cl–) are attracted by the electrostatic force of attraction and form the ionic bond.
- MgCl2 is ionic in nature but still, it has a covalent character also or you can say MgCl2 is not 100% ionic in nature.
- The difference in electronegativity between magnesium(1.31) and chlorine(3.16) is 3.16–1.31=1.85 which is higher than 1.7, hence, according to the Pauling scale, the bond formed between magnesium and a chlorine atom is ionic in nature.