What is the chemical formula of water? If you’re in lower secondary, you might simply answer H2O, which is correct. However, as upper secondary students, it’s essential to delve deeper and ask: How did it become H2O? Today, we’ll explore this further.

The chemical formula of water, H2O, is derived from the process of covalent bonding. Hydrogen atoms and oxygen atoms engage in covalent bonding, resulting in the formation of the compound H2O, commonly known as water. But let’s not stop there; let’s keep questioning.

What exactly happens during chemical bonding? Let’s uncover the answer together!

Chemical Bonding

A chemical bond occurs when atoms join together to form chemical compounds, aiming to achieve greater stability in the resulting product. This involves atoms sharing or transferring electrons from their outermost shell to create a new, homogeneous substance.

Before we proceed, it’s important to understand the classification of matter. Matter is generally classified into three categories: Elements, Compounds, and Mixtures.

Elements, Compounds & Mixtures

Atoms of elements seek to achieve a stable electronic configuration, often referred to as a noble gas configuration, by either gaining or losing electrons.

• Non-metals typically gain electrons to achieve a stable electronic configuration, forming negative ions.
• On the other hand, metals typically lose electrons to attain a stable electronic configuration, resulting in the formation of positive ions.

Different Types of Chemical Bonding

In upper secondary education, students typically learn about three primary types of chemical bonding: ionic bonding, covalent bonding, and metallic bonding. These concepts are fundamental to understanding the ways in which atoms interact and form chemical compounds.

Ionic Bonding

Let’s attempt a simple question on ionic bonding.

Q1: What type of bonding is found in aluminium oxide?

Look at your periodic table and determine the type of bonding in aluminium oxide. The answer is Ionic bonding.

This is because aluminium is a metal and oxygen are a non-metal. When aluminium reacts with oxygen to form aluminium oxide, the aluminium atoms lose electrons to become positively charged ions, and oxygen atoms gain electrons to become negatively charged ions. The electrostatic attraction between the positively charged aluminium ions and the negatively charged oxygen ions results in the formation of ionic bonds in aluminium oxide.

Did you answer correctly? It’s a straightforward question that should earn you full marks. Now, let’s delve into a more intricate concept.

Covalent Bonding

Let’s try a question on covalent bonding.

Q2: A student drew the following diagram to show the bonding in sodium chloride.

1. What type of bonding is shown in the student’s diagram of sodium chloride?

2. Does the bonding in (a) exist in sodium chloride? Give your reasons.

The answer is covalent bonding. Does the diagram seem weird to you? This is because covalent bonding DOES NOT exist in sodium chloride. It was a trick question!

Reason is because sodium is a metal and chlorine are a non-metal. One electron is transferred from a sodium atom to a chlorine atom for both to achieve stable octet structures.

We trust this question isn’t overly challenging for you, as we’re about to transition to an even more intricate concept.

Metallic Bonding

Here comes the most challenging question.

Q3: Lead has a typical metallic structure which is a lattice of lead ions surrounded by a ‘sea’ of mobile electrons. This structure is held together by attractive forces called a metallic bond. Explain why there are attractive forces in a metallic structure.

Did you arrive at an answer? We hope so, as leaving the question unanswered could result in significant loss of marks! The answer is:

The attractive forces in a metallic bond occur because the positively charged lead ions are attracted to the negatively charged electrons. This attraction between the ions and the electrons holds the metallic lattice together.

Did you get it right?!

Understanding chemical bonding is a substantial and complex undertaking, necessitating a strong grasp of fundamental concepts like those found in the periodic table. Regular review of elemental properties is essential for enhancing comprehension in this area. By consistently revisiting these principles, you can sharpen your understanding of chemical bonding, enabling your brain to respond more rapidly and accurately when faced with questions.

Here’s a food for thought:

Bonus Question: The diagram shows the electronic structure of a hydrogen atom.

(ai) Write the formula of the ion formed when the hydrogen atom loses its electrons.

(aii) Write the formula of the ion formed when the hydrogen atom gains an electron.

(b) Hydrogen combines with lithium to form lithium hydride. Draw a ‘dot and cross’ diagram to show the electronic structure of lithium hyride.

(c) Hydrogen combines with fluorine to form hydrogen fluoride. Draw a ‘dot and cross’ diagram to show the electronic structure of hydrogen fluoride.