|
|
Properties of Covalent Compounds

When you hear the words "chemical compound" what do you think of? Most people would probably talk about man-made drugs or the weird words they can't pronounce in their food's ingredients list. However, pretty much any material this isn't a singular element is made up of chemical compounds.

Mockup Schule

Explore our app and discover over 50 million learning materials for free.

Properties of Covalent Compounds

Illustration

Lerne mit deinen Freunden und bleibe auf dem richtigen Kurs mit deinen persönlichen Lernstatistiken

Jetzt kostenlos anmelden

Nie wieder prokastinieren mit unseren Lernerinnerungen.

Jetzt kostenlos anmelden
Illustration

When you hear the words "chemical compound" what do you think of? Most people would probably talk about man-made drugs or the weird words they can't pronounce in their food's ingredients list. However, pretty much any material this isn't a singular element is made up of chemical compounds.

In this article, we will be talking about a specific type of chemical compound: covalent compounds. We will be discussing what they are, the different types, and their common characteristics.

  • This article covers covalent compounds and their properties.
  • First, we will define what covalent compounds are.
  • Next, we will look the different types of covalent bond.
  • Then, we will learn the trends in covalent bond length.
  • Thereafter, we will learn some common characteristics of covalent compounds.
  • Lastly, we will look at some covalent compounds and their uses.

Covalent Compounds

Before we discuss their properties, let's first discuss what covalent compounds actually are.

A covalent compound is a compound that contains only covalent bonds. It is usually between two non-metals or a non-metal and a metalloid (element that shares both metal and non-metal properties).

A covalent bond is a bond where electrons are shared between elements.

As an example, here is a list of some covalent compounds:

  • H2O-Water

  • SiO2-Silicon dioxide (Silicon (Si) is a metalloid)

  • NH3-Ammonia

  • F2-Fluorine

Types of Covalent Bond

There are different types of covalent bond. These "types" can be broken up into two categories: categories based on number and categories based on electronegativity.

Let's break these types down based on category

Types of Covalent Bond: Numbers

There are three types of numbered covalent bonds:

  • Single
  • Double
  • Triple

Numbered covalent bonds depend on two factors: the number of electrons shared and the types of orbital overlap.

In terms of electrons shared, each bond contains 2 electrons. Therefore, double bonds share 4 electrons in total, while triple bonds share six.

And now for orbital overlap:

Orbitals are regions where electrons are likely to be found. A maximum of two electrons can exist in an orbital

There are 4 main types of orbitals, these are:

  • S-orbitals

    • Contain 1 sub-orbital (have a total of 2 electrons)

  • P-orbitals

    • Contain 3 sub-orbitals (have a total of 6 electrons, 2 each)

  • D-orbitals

    • Contain 5 sub-orbitals (have a total of 10 electrons, 2 each)

  • F-orbitals

    • Contain 7 sub-orbitals (have a total of 14 electrons, 2 each)

Below is what these orbitals look like:

Properties of Covalent Compounds Orbital Shapes StudySmarterFig.1 The different orbital and suborbital shapes

Single covalent bonds are caused by direct orbital overlap. These bonds are also called sigma (σ) bonds. In double and triple bonds, the first of these bonds is a σ-bond, while the other(s) are pi (π) bonds. Π-bonds are caused by sideways overlap between orbitals.

Below is an example of both types of bonds:

Properties of Covalent Compounds Examples of sigma and pi bonding StudySmarterFig.2-Examples of sigma and pi bonding

On the top row are examples of sigma bonding, while the bottom row is pi-bonding. Pi-bonding can only occur between orbitals of p-orbital energy or higher (i.e. d or f), while sigma bonding can occur between any orbitals.

Here is what these bonds look like:

Properties of Covalent Compounds SIngle, Double, and Triple bonds StudySmarterFig.3-Different types of numbered covalent bonds

Types of Covalent Bond: Electronegativity

The second category of covalent bond is based on electronegativity.

Electronegativity is the tendency for elements to attract/gain electrons.

Elements with the largest electronegativity are near the top right of the periodic table (fluorine) while elements with the smallest electronegativity are near the bottom left (francium), as shown below:

Properties of Covalent Compounds Table of electronegativities StudySmarterFig.4-Table of electronegativities

The two types of covalent bonds in this category are:

  • Non-polar covalent

  • Polar covalent

Here, "polarity" refers to the difference in electronegativity between elements. When one element has a significantly higher electronegativity (>0.4), the bond is considered polar.

What happens is the electrons are attracted to this more electronegative element, which causes an uneven distribution of electrons. This in turn causes the side with more electrons to be slightly negatively charged (δ-), and the side with fewer electrons to be slightly positively charged (δ+)

For example, below is HF (hydrogen fluoride), which is a polar covalent compound:

Properties of Covalent Compounds Hydrogen fluoride polar covalent bond StudySmarterFig.5-Hydrogen fluoride has a polar covalent bond

The separation of these charges is called a dipole.

In non-polar covalent bonds, there is a small enough difference in electronegativity (<0.4), that is distribution of charge doesn't occur, so there is no polarity. An example of this would be F2.

Determining Covalent Bond Length

Now, let's dive into bond length.

Bond length is the distance between the nuclei of elements in a bond

Covalent bond length is determined by bond order.

Bond order is the number of electron pairs shared between two bonded elements.

The higher the bond order, the shorter the bond. The reason why larger bonds are shorter is that the attractive forces between them are stronger.

When looking at diatomic (two-atom) compounds, the bond order is simply equal to the number of bonds (i.e. single=1, double=2, and triple=3). However, for compounds with more than two atoms, the bond order is equal to the total number of bonds minus the number of things bonded to that atom.

Let's do a quick example to explain:

What is the bond order of carbonate (CO32-)?

Properties of Covalent Compounds Carbonate ion StudySmarterFig.6--Structure of carbonate ion

Carbonate has a total of four bonds (two single, one double). However, carbon is only bonded to three things (the three oxygen), so the bond order is 4/3.

Characteristics and Properties of Covalent Compounds

Now that we've covered the basics, we can finally talk about covalent compound properties!

Here are some of the common properties/characteristics of covalent compounds:

  • Low melting and boiling points

    • While the bonds themselves are strong, the forces between molecules (called intermolecular forces) are weaker than those between ionic compounds, so they are easier to break/disrupt

  • Poor conductors of electricity

    • Covalent compounds don't contain ions/charged particles, so they can't transport electrons well

  • Soft and flexible

    • However, if the compounds are crystalline, this is not the case

  • Nonpolar covalent compounds dissolve poorly in water

    • Water is a polar compound, and the rule for dissolving is "like dissolves like" (i.e. polar dissolves polar and non-polar dissolved nonpolar)

Uses of Covalent Compounds

There are a plethora of covalent compounds, and as such, there are a plethora of uses for them. Here are just some of the many covalent compounds and their uses:

  • Sucrose (table sugar) (C12H22O11) is a common sweetener is foods

  • Water (H2O) is a necessary compound for all life

  • Ammonia (NH3) is used in several types of cleaning products

  • Methane (CH4) is the main component in natural gas and can be used for things such as home heating and gas stoves

Properties of Covalent Compounds - Key takeaways

  • A covalent compound is a compound that contains only covalent bonds. It is usually between two non-metals or a non-metal and a metalloid (element that shares both metal and non-metal properties.
    • A covalent bond is a bond where electrons are shared between elements.
  • There are three types of numbered covalent bond:
    • Single (share 2 electrons: 1 σ bond)
    • Double (share 4 electrons: 1 σ bond and 1 π bond)
    • Triple (share 6 electrons: 1 σ bond and 2 π bonds)
  • There are two types of covalent bond based on electronegativity (tendency to attract/gain electrons)
    • Non-polar
    • Polar
  • The greater the bond order, the shorter the bond
  • The main general properties of covalent compounds are:
    • Low melting and boiling points
    • Poor conductors of electricity
    • Soft and flexible
    • Nonpolar covalent compounds dissolve poorly in water

References

  1. Fig.1- The different orbital and suborbital shapes (https://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Single_electron_orbitals.jpg/640px-Single_electron_orbitals.jpg) by haade licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/)
  2. Fig.2-Examples of sigma and pi bonding (https://upload.wikimedia.org/wikipedia/commons/thumb/2/2b/Sigma_and_pi_bonding.jpg/640px-Sigma_and_pi_bonding.jpg) by Tem5psu licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/)

Frequently Asked Questions about Properties of Covalent Compounds

Here are some of the common properties/characteristics of covalent compounds:

  • Low melting and boiling points
  • Poor conductors of electricity
  • Soft and flexible
  • Nonpolar covalent compounds dissolve poorly in water

A covalent compound is a compound that contains only covalent bonds. It is usually between two non-metals or a non-metal and a metalloid (element that shares both metal and non-metal properties. A covalent bond is a bond where electrons are shared between elements.



A covalent compound only contains nonmetals or metalloids. 

As an example, here is a list of some covalent compounds:

  • H2O-Water 
  • SiO2-Silicon dioxide (Silicon (Si) is a metalloid)
  • NH3-Ammonia
  • F2-Fluorine 

There are 5 different types of covalent bonds in two different categories. These categories are based on the number of bonds and electronegativity. 


These bond types are:

  • Single
  • Double
  • Triple
  • Polar
  • Nonpolar


Three physical properties of covalent compounds are:

  • Low melting points
  • Poor conductors of electricity
  • Soft and flexible

Test your knowledge with multiple choice flashcards

True or False: Covalent compounds are only between nonmetals

Which of the following is NOT a type of covalent bond?

How many electrons are shared in a (single) covalent bond?

Next

Join over 22 million students in learning with our StudySmarter App

The first learning app that truly has everything you need to ace your exams in one place

  • Flashcards & Quizzes
  • AI Study Assistant
  • Study Planner
  • Mock-Exams
  • Smart Note-Taking
Join over 22 million students in learning with our StudySmarter App Join over 22 million students in learning with our StudySmarter App

Sign up to highlight and take notes. It’s 100% free.

Entdecke Lernmaterial in der StudySmarter-App

Google Popup

Join over 22 million students in learning with our StudySmarter App

Join over 22 million students in learning with our StudySmarter App

The first learning app that truly has everything you need to ace your exams in one place

  • Flashcards & Quizzes
  • AI Study Assistant
  • Study Planner
  • Mock-Exams
  • Smart Note-Taking
Join over 22 million students in learning with our StudySmarter App