A Covalent Chemical Bond is One in Which _____
Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to proceeds more stability, which is gained by forming a full electron shell. Past sharing their outer near (valence) electrons, atoms can fill up their outer electron beat out and gain stability. Nonmetals will readily class covalent bonds with other nonmetals in social club to obtain stability, and tin can form anywhere betwixt ane to three covalent bonds with other nonmetals depending on how many valence electrons they posses. Although it is said that atoms share electrons when they class covalent bonds, they do not ordinarily share the electrons equally.
Merely when two atoms of the same element form a covalent bond are the shared electrons actually shared equally between the atoms. When atoms of different elements share electrons through covalent bonding, the electron will be drawn more than toward the cantlet with the higher electronegativity resulting in a polar covalent bail. When compared to ionic compounds, covalent compounds usually take a lower melting and boiling bespeak, and accept less of a tendency to dissolve in water. Covalent compounds tin be in a gas, liquid, or solid land and exercise not comport electricity or heat well. The types of covalent bonds tin can be distinguished past looking at the Lewis dot structure of the molecule. For each molecule, at that place are different names for pairs of electrons, depending if it is shared or not. A pair of electrons that is shared between two atoms is called a
. A pair of electrons that is
shared between 2 atoms is called a
requires all atoms in a molecule to take 8 valence electrons–either by sharing, losing or gaining electrons–to become stable. For Covalent bonds, atoms tend to share their electrons with each other to satisfy the Octet Rule. It requires eight electrons because that is the amount of electrons needed to fill a
p– orbital (electron configuration); also known as a noble gas configuration. Each atom wants to become equally stable as the noble gases that have their outer valence vanquish filled because noble gases have a accuse of 0. Although it is important to call up the “magic number”, 8, annotation that in that location are many Octet rule exceptions.
Example: Equally you lot tin run into from the moving picture below, Phosphorus has only 5 electrons in its outer trounce (bolded in red). Argon has a full of eight electrons (bolded in ruby), which satisfies the Octet Dominion. Phosphorus needs to gain 3 electrons to fulfill the Octet Rule. Information technology wants to be like Argon who has a full outer valence vanquish.
More than examples can be found here.
is when ii electrons–one pair of electrons–are shared between two atoms. It is depicted by a single line betwixt the ii atoms. Although this course of bond is weaker and has a smaller density than a double bail and a triple bond, information technology is the virtually stable because it has a lower level of reactivity meaning less vulnerability in losing electrons to atoms that desire to steal electrons.
Example 1: HCl
Below is a Lewis dot construction of Hydrogen Chloride demonstrating a unmarried bond. As we can encounter from the picture below, Hydrogen Chloride has 1 Hydrogen atom and ane Chlorine cantlet. Hydrogen has only ane valence electron whereas Chlorine has 7 valence electrons. To satisfy the Octet Rule, each atom gives out ane electron to share with each other; thus making a single bail.
is when ii atoms share 2 pairs of electrons with each other. It is depicted by two horizontal lines between two atoms in a molecule. This type of bond is much stronger than a single bond, merely less stable; this is due to its greater corporeality of reactivity compared to a unmarried bail.
Below is a Lewis dot structure of Carbon dioxide demonstrating a double bond. Every bit you can meet from the moving picture below, Carbon dioxide has a full of 1 Carbon cantlet and two Oxygen atoms. Each Oxygen atom has 6 valence electrons whereas the Carbon atom only has four valence electrons. To satisfy the Octet Rule, Carbon needs 4 more valence electrons. Since each Oxygen atom has 3 lone pairs of electrons, they tin each share i pair of electrons with Carbon; as a result, filling Carbon’southward outer valence shell (Satisfying the Octet Rule).
is when three pairs of electrons are shared between two atoms in a molecule. It is the least stable out of the 3 general types of covalent bonds. It is very vulnerable to electron thieves!
Example three: Acetylene
Below is a Lewis dot structure of Acetylene demonstrating a triple bond. As you can encounter from the picture show below, Acetylene has a total of 2 Carbon atoms and ii Hydrogen atoms. Each Hydrogen atom has i valence electron whereas each Carbon atom has four valence electrons. Each Carbon needs four more electrons and each Hydrogen needs 1 more than electron. Hydrogen shares its only electron with Carbon to get a full valence shell. Now Carbon has five electrons. Because each Carbon atom has 5 electrons–1 single bond and 3 unpaired electrons–the ii Carbons tin share their unpaired electrons, forming a triple bond. Now all the atoms are happy with their total outer valence crush.
Polar Covalent Bond
Polar Covalent Bail
is created when the shared electrons between atoms are not equally shared. This occurs when one cantlet has a higher electronegativity than the atom it is sharing with. The atom with the higher electronegativity will have a stronger pull for electrons (Similiar to a Tug-O-War game, whoever is stronger commonly wins). As a result, the shared electrons will be closer to the atom with the higher electronegativity, making information technology unequally shared. A polar covalent bail will outcome in the molecule having a slightly positive side (the side containing the atom with a lower electronegativity) and a slightly negative side (containing the atom with the higher electronegativity) considering the shared electrons will be displaced toward the atom with the higher electronegativity. As a consequence of polar covalent bonds, the covalent compound that forms will take an electrostatic potential. This potential will brand the resulting molecule slightly polar, assuasive information technology to form weak bonds with other polar molecules. One example of molecules forming weak bonds with each other as a result of an unbalanced electrostatic potential is hydrogen bonding, where a hydrogen atom will interact with an electronegative hydrogen, fluorine, or oxygen atom from another molecule or chemical grouping.
Example: Water, Sulfide, Ozone, etc.
Every bit you can see from the picture above, Oxygen is the large buff creature with the tattoo of “O” on its arm. The little bunny represents a Hydrogen cantlet. The blue and red bow tied in the centre of the rope, pulled by the two creatures represents–the shared pair of electrons–a unmarried bond. Because the Hydrogen atom is weaker, the shared pair of electrons will be pulled closer to the Oxygen atom.
Nonpolar Covalent Bond
Nonpolar Covalent Bail
is created when atoms share their electrons equally. This normally occurs when two atoms have like or the same electron analogousness. The closer the values of their electron analogousness, the stronger the attraction. This occurs in gas molecules; also known equally diatomic elements. Nonpolar covalent bonds have a similar concept as polar covalent bonds; the atom with the higher electronegativity will depict away the electron from the weaker ane. Since this statement is true–if we use this to our diatomic molecules–all the atoms will have the aforementioned electronegativity since they are the aforementioned kind of chemical element; thus, the electronegativities volition abolish each other out and will have a charge of 0 (i.e., a nonpolar covalent bond).
Examples of gas molecules that have a nonpolar covalent bond: Hydrogen gas atom, Nitrogen gas atoms, etc.
As you tin run across from the picture show higher up, Hydrogen gas has a full of 2 Hydrogen atoms. Each Hydrogen atom has 1 valence electron. Since Hydrogen can only fit a max of 2 valence electrons in its orbital, each Hydrogen atom just needs one electron. Each atom has 1 valence electron, so they tin can just share, giving each atom two electrons each.
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- Bacskay, George Grand.; Reimers, Jeffrey R.; Nordholm, Sture.
“The Mechanism of Covalent Bonding.”
J. Chem. Educ.
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J. Chem. Educ.
1. Make up one’s mind the type(s) of bond(s) in
- Benzene (Chalf dozenHvi)
- F2(Fluorine gas)
two. Write the electron configuration and decide how many electrons are needed to achieve the nearest noble-gas configuration for the following:
- Arsenic (As)
- Silicon (Si)
- Tellurium (Te)
3. Make up one’s mind which molecules are polar and which molecules are nonpolar for the following:
- Oxygen gas (O2
- Hydrochloric acid (HCl)
- Carbon dioxide (CO2)
4. Which of the following statements are true? (There tin can exist more than i true statement.)
- A covalent bail is the same every bit a ionic bond.
- The Octet rule just applys to molecules with covalent bonds.
- A molecule is polar if the shared electrons are every bit shared.
- A molecule is nonpolar if the shared electrons are are equally shared.
- Marsh gas gas (CH4
) has a nonpolar covalent bond because information technology is a gas.
Solution: Only d) is truthful.
5. Match each cantlet or molecule with its corresponding letter(s):
- Nitrogen gas
- Carbon monoxide
- Hydrogen gas
a) Nonpolar covalent bail
b) Polar covalent bond
c) Follows the Octet Rule
d) Noble gas
e) Ii lone pairs
f) Unmarried bail
- Nitrogen gas: a), c), eastward)
- Argon: c), d)
- Carbon monoxide: b), c), e)
- Hydrogen gas: c), f)
Contributors and Attributions
- Camy Fung (UCD), Nima Mirzaee (UCD)
A Covalent Chemical Bond is One in Which _____