Chemical Bonds and Ionic Bonding

Think of atoms as being desperate to achieve the perfect electron setup - a full outer shell. Ionic bonding happens when metals and non-metals team up to sort this out by transferring electrons completely.

When sodium (with one lonely outer electron) meets chlorine (missing just one electron), magic happens. Sodium gives up its electron to chlorine, creating sodium chloride - table salt! The sodium becomes a positive cation $Na+$ because it now has more protons than electrons, whilst chlorine becomes a negative anion $Cl-$ for the opposite reason.

These oppositely charged ions are like magnets - they're strongly attracted to each other through electrostatic attraction. This creates an ionic bond, and thousands of these ions arrange themselves into a giant lattice structure that's incredibly organised and stable.

Top Tip: Remember that metals always lose electrons (becoming positive), whilst non-metals gain electrons (becoming negative) in ionic compounds.

Properties of Ionic Compounds and Covalent Bonding Basics

Ionic compounds like salt have some pretty predictable properties once you understand their structure. They have high melting points because breaking apart all those strong electrostatic attractions requires loads of energy. They dissolve in water because water molecules can surround and attract the ions. Most importantly, they only conduct electricity when melted or dissolved - that's when ions are free to move and carry charge.

Covalent bonding works completely differently from ionic bonding. Instead of transferring electrons, non-metal atoms share electrons to achieve full outer shells. This sharing creates covalent bonds that hold atoms together in molecules.

You'll encounter single bonds (sharing 2 electrons), double bonds (sharing 4 electrons), and triple bonds (sharing 6 electrons). Some molecules like oxygen (O₂) and chlorine (Cl₂) are called diatomic molecules because they contain two identical atoms bonded together.

Remember: Covalent bonding = sharing electrons between non-metals, whilst ionic bonding = transferring electrons from metals to non-metals.

Molecular vs Giant Covalent Structures

Covalent compounds come in two completely different forms, and this makes all the difference to their properties. Molecular covalent structures are small molecules held together by strong covalent bonds within each molecule, but only weak van der Waals' forces between different molecules.

These molecular compounds have low melting points because you only need to overcome the weak forces between molecules, not the strong covalent bonds within them. They don't conduct electricity because there are no charged particles free to move around. Think water, carbon dioxide, or iodine.

Giant covalent structures are completely different beasts. Diamond is the perfect example - every carbon atom bonds to four others in a strong, three-dimensional network. This creates an incredibly hard material with a very high melting point because you'd need to break loads of strong covalent bonds to melt it.

Allotropes like diamond are different physical forms of the same element. Carbon has several allotropes, each with unique properties despite being made of identical atoms.

Key Point: Small molecules = weak forces between molecules = low melting points. Giant structures = strong bonds throughout = high melting points.

Carbon Allotropes and Metallic Bonding

Graphite and graphene show how structure determines properties brilliantly. In graphite, carbon atoms arrange in hexagonal layers with strong covalent bonds within layers but weak forces between them. This makes graphite soft (layers slide over each other) but also conductive because each carbon has one delocalised electron free to move and carry charge.

Graphene is essentially a single layer of graphite - just one atom thick! It's incredibly strong (100 times stronger than steel) yet super light, making it perfect for future technologies like flexible electronics and solar cells.

Metallic bonding creates a "sea of delocalised electrons" surrounding positive metal ions arranged in regular rows. This unique structure explains why metals conduct electricity brilliantly - electrons move freely throughout the structure. It also explains why metals are malleable and ductile - the layers of atoms can slide past each other without breaking bonds.

Alloys are mixtures containing at least one metal, designed to improve properties like strength or corrosion resistance.

Think About This: The same element (carbon) can be super hard (diamond), slippery (graphite), or incredibly strong yet flexible (graphene) - it's all about arrangement!

Properties Summary and Real-World Applications

Understanding bonding types helps predict material properties perfectly. Metals like copper and aluminium have high melting points, conduct electricity, and can be shaped easily - that's why copper works brilliantly for electrical wiring and aluminium for aircraft construction.

The summary table shows clear patterns: ionic compounds conduct only when molten or dissolved, molecular covalent compounds generally have low melting points and don't conduct, whilst giant covalent and metallic structures have high melting points with varying electrical properties.

Giant covalent structures like diamond don't conduct electricity (except graphite and graphene), making diamond perfect for cutting tools. Metallic bonding creates materials that are both strong and conductive, explaining why metals dominate construction and electronics.

Alloys combine different elements to create materials with improved properties - think steel $iron + carbon$ for stronger construction materials.

Exam Success: Learn the property patterns for each bonding type - they're predictable once you understand the underlying structure!