Chemistry - BONDING, STRUCTURE, + THE PROPERTIES (C2)

Ionic Bonding -

What is ionic bonding, + how does it occur?

Ionic bonding occurs when a metal transfers electrons to a non-metal. The metal loses electrons to form a positively charged ion (cation), + the non-metal gains electrons to form a negatively charged ion (anion). These oppositely charged ions - held together by strong electrostatic forces.

Ionic Bonding -

Why do ionic compounds have high melting + boiling points?

Ionic compounds have high melting + boiling points because they consist of a giant ionic lattice w/ strong electrostatic forces between oppositely charged ions that require a lot of energy to overcome.

Ionic Bonding -

Why can ionic compounds conduct electricity when molten / dissolved in water but not when solid?

In solid form, the ions - fixed in place + can’t move. When molten / dissolved in water, the ions - free to move + carry an electrict current.

Covalent Bonding -

What is covalent bonding, + which types of elements form covalent bonds?

Covalent bonding occurs when two non-metal atoms share pairs of electrons to achieve a full outer shell. Non-metals form covalent bonds.

Covalent Bonding -

What are the properties of simple molecular covalent substances?

Simple molecules have low melting + boiling points because they’ve weak intermolecular forces, even though the covalent bonds w/in the molecules are strong. They don’t conduct electricity because they’ve no free electrons / ions.

Covalent Bonding -

Why do substances made of small molecules have low melting + boiling points?

They’ve weak intermolecular forces between the molecules, which require little energy to break.

Covalent Bonding -

What is the difference between simple molecular substances + giant covalent structures?

Simple molecular substances consist of small molecules w/ weak intermolecular forces. Giant covalent structures consist of a vast number of atoms bonded by strong covalent bonds throughout the structure, resulting in very high melting + boiling points.

Giant Covalent Structures -

Describe the structure + properties of diamond.

Diamond’s made of carbon atoms, each bonded to four other in a tetrahedral structure. It has a very hard structure, high melting point, + doesn’t conduct electricity because there are no free electrons.

Giant Covalent Structures -

Describe the structure + properties of graphite.

Graphite’s made of carbon atoms bonded in layers, w/ each atom bonded to three others in hexagonal sheets. One electrons per atom is delocalised, allowing it to conduct electricity. Layers can slide over eachother, making graphite soft + slippery.

Giant Covalent Structures -

What is graphene + what are its key properties?

Graphene is a single layer of carbon atoms arranged in a hexagonal lattice. It’s strong, lightweight, + an excellent conductor of heat + electricity due to delocalised electrons.

Metallic Bonding -

What is metallic bonding + which elements form metallic bonds?

Metallic bonding occurs in metals where positive metal ions - surrounded by a sea of delocalised electrons. The electrostatic attraction between the ions + electrons holds the structure together.

Metallic Bonding -

Why’re metals good conductors of electricity + heat?

Metals have delocalised electrons that can move freely throughout the structure, transferring energy + electrical current.

Metallic Bonding -

Why are metals malleable + ductile?

The layers of atoms in a metal can slide over eachother w/out breaking the metallic bonds, allowing metals to be hammered / drawn into wires.

Metallic Bonding -

Why are alloys harder than pure metals?

Alloys contain atoms of different sizes, which distort the regular layers in a metal structure. This make it more difficult for layers to slide over eachother, increasing hardness.

States of Matter & Particle Models -

What are the limitations of the particle model in representing solids, liquids, + gases?

The particle model assumes particles - solid, inelastic spheres w/ no forces between them, which isn’t accurate. Real particles can be atoms, ions, / molecules + can interact through forces.

States of Matter & Particle Models -

Describe the particle arrangement in solids, liquids, + gases.

Solids - Tightly packed in a fixed, regular arrangement; particles vibrate.

Liquids - Close together but can move past one another; irregular arrangement.

Gases - Far apart, move randomly + freely in all directions.

Polymers -

What is a polynmer, + how is it formed?

A polymer - a long chain molecule made by joining many small molecules (monomers) through covalent bonds in a process called polymerisation.

Polymers -

How do the properties of polymers compare to simple molecular + giant covalent substances?

Polymers generally have higher melting points than simple molecular substances due to stronger intermolecular forces, but lower melting points than giant covalent substances.

Nanoparticles -

What is the size range of nanoparticles?

Between 1 - 100 nanometres (nm) in size, consisting of a few hundred atoms.

Nanoparticles -

Why do nanoparticles have different properties from the same substance in bulk form?

Nanoparticles have high surface area : volume ratio, which enhances their reactivity + allows for unqiue physical + chemical properties.

Nanoparticles -

What are some uses of nanoparticles?

Used in medicine (drug delivery), electronics, sun creams, cosmetics, catalysts, + deodorabts due to their enhanced properties.

Nanoparticles -

What are some potential risks of using nanoparticles?

The effects of nanoparticles on human health + the environment aren’t full understoof. They may be toxic / cause unintended interactions in the body / ecosystems.