100 Nano-Stories: Electronegativity!
Episode #52: Covalent & Ionic Bonds + Calculating Electronegativity!
Preface! ✨
It’s your favorite material science & nanotechnology enthusiast! A couple of days ago, I explained my idea on how to improve aerogels for climate change purposes! If you’re interested to see what I cooked up there, check it out!
But for today, I wanted to clarify electronegativity in all aspects of chemicals, especially when it comes to making the hydrophobic aerogels for my idea!
We want hydrophobic (repels water) aerogels so that the aerogel does not rearrange its chemical structure and collapses a.k.a. destroys itself.
So today, let’s explain the difference in electronegativity in polar, non-polar, covalent, and ionic bonds!
Ah, I see! You don’t know what these terms mean! Don’t worry, I’ll explain it all in under 5 minutes!
Electronegativity Explained! 💡
Fundamental Concepts! 🔑
To begin our journey in electronegativity, let’s define all these terms, just to get a clearer vision of what we will be tackling in the examples.
Polar molecules mean that the electrical charges of the molecule are not evenly distributed. This leads to electronegativity. But in aerogels, you can find OH groups attached to the surface of the aerogel. Anything that is directly attached to hydrogen (hydrogen-bonding) is a polar molecule.
Non-polar molecules mean that the electrical charges of the molecule are evenly distributed. No positive or negative charges are formed in the molecule. There is still electronegativity, but the electronegativity is low enough for them to repel water or have hydrophobicity. Anything that is an alkane (CH4), alkene (CH2 = CH2), or alkyne (H-C ≡ C-H)is non-polar because of its electronegativity.
Covalent bonds are chemically bonded because the electrons are being shared evenly! Covalent bonds form between two nonmetals! Sharing is caring! 😄
Ionic bonds are essentially giving away an electron to another atom to stabilize their outer electron shell. Ionic bonds form between a metal and a nonmetal. So you could say that ionic bonds give away/steal their electrons! 😂
Electronegativity is the chance that a pair of elections will be attached to a certain atom. If the difference between the electronegativity is greater or equal to 0.5, the molecule is polar. If the difference in electronegativity in the molecule is less than 0.5, the molecule is non-polar. Covalent bonds occur at an electronegativity below around 1.7, and ionic bonds occur at an electronegativity equal to or greater around 1.7.
Examples! 🔑
Now that we have defined all of our terms, let’s use some examples to demonstrate our understanding of electronegativity!
The electronegativity of an Oxygen atom is 3.44. The electronegativity of a Hydrogen atom is 2.1. The overall difference in electronegativity is 1.34, which is more than the required 0.5 difference in electronegativity to become a polar/hydrophilic molecule.
Essentially, any molecule that is composed of only oxygen and hydrogen (water) will have polar bonds and be covalent.
The electronegativity of a Carbon atom is 2.5. The electronegativity of a Hydrogen atom is 2.1. The overall difference in electronegativity is 0.4, which is less than the required 0.5 difference in electronegativity. The difference in electronegativity results in a non-polar/hydrophobic molecule.
Essentially, any molecule that is composed of only carbon or hydrogen will have non-polar bonds and still have covalent bonds.
An ionic bond would be salt or known as NaCl.
Na → Sodium. Sodium has an electronegativity of 0.9.
Cl → Chlorine. Chlorine has an electronegativity of 3.0.
You would subtract the highest number of electronegativity from the smaller number of electronegativity. So 3.0 minus 0.9 = 2.1 difference in electronegativity! This means that this is an ionic bond, and an electron from sodium has been stolen to fill up the outer electron shell of chlorine.
Notice how sodium is the metal, and chlorine is the nonmetal in this chemical reaction. This is what allows us to create the ionic bonds to stabilize.
Closing Thoughts! 💭
You still confused about what I said, reader?
Ok, perfect! Now you understand how to tell the difference in a polar, nonpolar, covalent, and ionic bond for electronegativity!
See you tomorrow for clarity and understanding of reading an element on the periodic table! ✌🏽
Vocabulary! 📓
Polar molecules → The electrical charges of the molecule are not evenly distributed. This leads to electronegativity. But in aerogels, you can find OH groups attached to the surface of the aerogel. Anything that is directly attached to hydrogen (hydrogen-bonding) is a polar molecule.
Non-polar molecules → The electrical charges of the molecule are evenly distributed. No positive or negative charges are formed in the molecule. There is still electronegativity, but the electronegativity is low enough for them to repel water or have hydrophobicity. Anything that is an alkane (CH4), alkene (CH2 = CH2), or alkyne (H-C ≡ C-H)is non-polar because of its electronegativity.
Covalent bonds → They are chemically bonded because the electrons are being shared evenly! Covalent bonds form between two nonmetals! Sharing is caring! 😄
Ionic bonds → Giving away an electron to another atom to stabilize their outer electron shell. Ionic bonds form between a metal and a nonmetal. So you could say that ionic bonds give away/steal their electrons! 😂
Electronegativity → The chance that a pair of elections will be attached to a certain atom. If the difference between the electronegativity is greater or equal to 0.5, the molecule is polar. If the difference in electronegativity in the molecule is less than 0.5, the molecule is non-polar. Covalent bonds occur at an electronegativity below around 1.7, and ionic bonds occur at an electronegativity equal to or greater around 1.7.
Hydrophobic Aerogel → Non-Polar molecules are attached to the surface of the aerogel. Hydrophobic Aerogels will repel water.
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