O-Level Chemistry Video: Writing Chemical Formulae of Ionic Compounds and Covalent Substances


It is very important for Chemistry students to master the skills of writing the correct chemical formulae for ionic compounds and covalent substances (elements or compounds) because almost every other Chemistry topics are related to it.

For students in Singapore, they will learn them in Sec 3 (some as early as Sec 2) whether they are based in GCE O-Level Pure Chemistry syllabus, or IGCSE and IP programs.

I observed that students who join my weekly O-Level Pure Chemistry tuition classes are generally not confident about writing the correct formula of a substance when they first came in. So i will usually work with them promptly to beef up these fundamentals first. You should do so likewise.

Before we even start, do take a look at the recent blog post about the different types of bonding: Ionic, Covalent and Metallic, and the structures associated with it first.

At the end of the two videos, you will learn the different skills and strategies to write the chemical formulae for both ionic compounds and covalent substances quickly, which are different.

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Feel free to share these videos with your friends who needs help in mastering Chemistry.

1st Video: Writing Chemical Formulae of Ionic Compounds

Length of video: 5.08 mins

Direct link: https://youtu.be/3hyUy6DQWhU

Key points of the video to deduce the formula of ionic compounds:

  1. Write down the respective ions with their charges, e,g, Xm+Yn-
  2. Move the values m and n diagonally but without the charges
  3. Use ( ) when it involves more than 1 unit of polyatomic ion

2nd Video: Writing Chemical Formulae of Covalent Substances

Length of video: 12.13 mins

Direct link: https://youtu.be/w_Y6rIlIkb4

Key points of the video to deduce the formula of covalent substances:

  1. Non-metal atoms share valence electrons to achieve noble/full electronic configuration
  2. Duplet (2 valence electrons) or Octet (8 valence electrons) configuration after bonding
  3. Count the atoms involved to determine the chemical formula

I hope you find the content easy for your understanding and if you have any questions, leave me a comment below.

PS: Under related articles below, there are several blog post discussions and questions related to Chemical Bonding. You can also do a keyword search using the sidebar at the top right hand corner.

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Many people talked about teaching Chemistry, I simply LOVE it. I am a passionate Chemistry Coach based in Singapore, Southeast-Asia and aspire to be one of the most dynamic, powerful and humorous speakers in Asia. My 18+ years of coaching experience has equipped me to understand the true reasons why students are not able to perform well in Chemistry, and allow me to structure my teaching methodology to cater to different levels of learners. If you have found this post useful, please share it with your friends. I would really appreciate it! Sean Chua

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