CHEMICAL BONDING

 Hello lovely students. I hope we are all doing well? Today we are going to learn about one of the science topics that students find it difficult to understand. This is Chemical bonding. 

 Imagine atoms as tiny building blocks. They want to be happy and stable. One way they do this is by sticking together with other atoms. This sticking together is called chemical bonding

Why do atoms bond?

• Stability: Atoms want to have a full outer shell of electrons. This makes them feel happy and stable.
• Energy: Bonding can release energy, making the atoms more stable.

Remember the electronic configuration of the first 20 elements as we are going to use this a lot in our studies today. Example the electronic configuration of Oxygen is 2, 6, Calcium is 2,8,8,2 and the others. 

Now lets move on. 

Types of Chemical Bonding

There are three main types of chemical bonding:

Ionic Bonding:

• This happens when one atom gives an electron to another atom.
• The atom that gives the electron becomes a positive ion.
• The atom that receives the electron becomes a negative ion.
• Opposite charges attract, so the ions stick together.

This means that Oxygen has 6 electrons in its valence (outermost) shell. But that shell needs 8 electrons and as such needs two more to become stable. This is why oxygen is an anion (negatively charged). Calcium has 2 electrons on its outermost shell. (this electrons are to be thrown away so its a positively charged ion i.e cation)

When these ions meet, oxygen borrows the two electrons from calcium making them stick together as Calcium oxide(CaO). The name of the positive ion is mentioned in full whilst the anion is simplified with the prefix ide. 

Another example is Aluminum oxide (Al₂O₃). This is formed because Aluminum has three valence electrons and oxygen needs two. So two different aluminum ions can make three oxygens stable. This is done by the figure below

Try forming ionic bonds with the following elements

• Calcium and chlorine
• Magnesium and oxygen
• Lithium and Nitrogen

NB: Ionic bonds are formed by combining a cation and an anion. 

Covalent Bonding:

• This happens when atoms share electrons.
• Both atoms are happy because they both have a full outer shell.

This means that they are formed basically by anions coming together so their outermost shells will become stable. 

Example: Water molecules are formed by covalent bonding. Oxygen shares electrons with two hydrogen atoms.

This is shown in the figure below.

The electrons of oxygen are the dots and hydrogen is x

Other examples of covalent bonds include Hydrogen molecule - H₂, Oxygen molecule - O₂, Chlorine molecule - Cl₂, Carbon dioxide - CO₂, Ammonia gas - NH₃ and Methane gas - CH_4.

NB: Covalent bonds are formed by anions mostly and elements that exist both as cations and anions (such as hydrogen and Carbon)

Metallic Bonding:

• This happens in metals.
• The electrons are free to move around the metal.
• This is why metals are good conductors of electricity.

Metallic bonding is a type of chemical bond that occurs between metal atoms. In this type of bond, the outer electrons of metal atoms are free to move throughout the entire metal structure. Think of it like a pool of electrons that can move freely.

Key Features of Metallic Bonding:

• Sea of Electrons: The outer electrons of metal atoms are loosely held and can move freely throughout the metal lattice, forming a "sea of electrons."
• Positive Ions: The metal atoms, without their outer electrons, become positive ions.
• Attraction: The positive ions are attracted to the negatively charged sea of electrons, holding the metal together.

Properties of Metals:

• Conductivity: Because of the free-moving electrons, metals are good conductors of electricity and heat.
• Malleability: Metals can be hammered into thin sheets because the atoms can slide past each other without breaking the bond.
• Ductility: Metals can be drawn into wires because the atoms can be pulled apart without breaking the bond.
• Luster: Metals often have a shiny appearance due to the interaction of light with the free electrons.

In summary, metallic bonding is a unique type of chemical bond that gives metals their characteristic properties. The free-moving electrons are the key to understanding why metals are good conductors, malleable, ductile, and often shiny.

Here are some examples of metals that exhibit metallic bonding:

• Iron: Used in steel, tools, and machinery.
• Copper: Used in electrical wiring, plumbing, and coins.
• Aluminum: Used in aircraft, cans, and foil.
• Gold: Used in jewelry, electronics, and dentistry.
• Silver: Used in jewelry, photography, and electronics.
• Lead: Used in batteries, plumbing, and ammunition.
• Zinc: Used in batteries, alloys, and coatings.

Essentially, any element that is classified as a metal (such as those found in the periodic table) is likely to exhibit metallic bonding.

Remember: Atoms bond to become more stable. The type of bond depends on the properties of the atoms involved.