Bonding + Properties

Properties of metals

High MP/BP, low ionisation energy, electrical + thermal conductivity, dense, hard, lustrous, malleable, ductile.

Properties of transition metals

Harder, higher density, higher melting point, some strong magnetic properties, often silver.

Describe the metallic bonding model

Cations arranged in regular 3D lattice with a sea of delocalised electrons holding them together through electrostatic attraction.

Why do transition metals have different properties compared to metals?

Smaller atomic radius due to their increased core charge, allowing them to be more tightly packed with stronger bonds

Why are metals malleable?

When force is applied, the rows of cations shift against each other but are still held together by the sea of delocalised electrons.

Why are metals lustrous?

The delocalised electrons reflect all wavelengths of light

Metal + oxygen —> ?

Metal oxide

Metal + acid —> ?

Hydrogen gas + metal salt

How does ionic bonding work?

One atom donates valence electrons to another atom, forming a cation and anion. They are bonded by the electrostatic attraction, creating a 3D crystal lattice structure.

Properties of ionic compounds

High MP, hard + brittle, conductive in liquid form, sometimes soluble.

Give 2 examples of ionic compounds and their uses.

Magnesium oxide is used for lining furnaces. Sodium hydrogen carbonate is used as a raising agent in baking.

What are covalent molecules?

Discrete clusters of non-metals atoms of the same element bonded together by sharing valence electrons.

Properties of simple covalent structures

Low MP/BP, non-conductive, soft.

Properties of giant covalent structures

Strong, high MP/BP, non-conductive

What are giant covalent structures?

Huge numbers of non-metal atoms covalently bonded together, generally arranged in regular repeating lattices.

3 examples of covalent network structures

Diamond, graphite, silicon dioxide.

Why do covalent molecular substances have low MP/BP?

Weak intermolecular forces don’t require lots of heat energy to break.

Why do covalent network substances have high MP/BP?

Strong intermolecular forces require lots of heat energy to break.

Why are covalent molecular substances soft?

Weak intermolecular forces allow molecules to be easily separated.

Why are covalent substances generally non-conductive?

They lack free particles to carry electrical charge.

What is a covalent bond?

A chemical bond that forms between two non-metal atoms when they share one or more pairs of electrons in order to achieve an octet.

What atoms do covalent bonds form from?

2 or more non-metal atoms with similar electronegativities.

Why do ionic substances have high melting points?

The strong electrostatic attraction between the cations and anions requires lots of energy to overcome.

Why are ionic compounds brittle?

When force is applied, ions with the same charges align and repel.

What are allotropes?

Different forms of elements made up of the same atoms in different structures.

Describe diamond and its properties

A covalent network lattice of carbon atoms held together by strong covalent bonds. It is brittle because its compact structure doesn’t allow much movement, and non-conductive due to the lack of free electrons.

Describe graphite and its properties.

Layers of carbon atoms arranged in a 2D hexagonal structure joined together by weak intermolecular forces. Hard in one direction but soft in the other due to strong covalent bonds and weak dispersion forces. Conductor of electricity due to each atom forming 3 bonds, leaving one valence electron that is free to carry charge.

Describe the structure of fullerenes.

An allotrope of carbon made up of hexagonal/pentagonal rings of carbon bonded together to form spheres/tubes. Each carbon bonds with three other carbons, leaving one delocalised electron.

Properties of fullerenes.

Highly stable, can withstand extreme temperatures and pressures, reactive.

Applications of fullerenes

Used in medicine as their cage-like structure allows them to trap and transport drugs or radioactive isotopes through the bloodstream, and are also used as contrast agents in medical imaging. Used in organic solar cells because they easily accept and transport electrons.