Chapter 4d: Solids – lattice energy

In gases, the heat capacity was a resultant of translation, vibration and rotation. In a solid, there is no translation and no rotation. The atoms may vibe around their equilibrium position. The vibration involves a potential energy and a kinetic energy, each term participating for ½R. As a solid has 3 dimensions, Cv=3R However, this […]

Chapter 4c: Solids – crystallography

A characteristic of the solids is that they have their own shape. Liquids are taking the shape of their recipient and gases take all the available space. So solids have their own shape but some are malleable, can be cut, be creased or smashed or can be very rigid. As explained at the beginning of […]

Chapter 4a: The states of matter: Gas

The states of the matter We can consider 3 different states –gas, liquid and solid– and a melange of them. One important difference between the three states of the matter is the volume they occupy. A gaz takes all the available space, a liquid takes the form of its recipient and a solid has its […]

Chapter 1f: Redox reactions

Oxido-reductions, or redox, are reactions involving a transfer of charge between molecules.  During such reactions, some chemical energy is transformed into electrical energy. An oxidation reaction is a reaction during which a substrate (molecule, atom or ion) loses electrons. A reduction reaction is a reaction during which a substrate gains electrons. An oxidant is a […]

Chapter 1e: Liaisons and molecular orbitals

Atoms make liaisons because they get more stability. A proof is that to break a liaison, we need to give energy to the molecule. Atoms in a molecule are at a given distance, and oscillate slightly from this position depending on the energy they receive. The atoms cannot oscillate at any frequency. There are authorized […]

Chapter 1c: Electronic structure of atoms

Let’s resume what we know from the atoms: atoms can be broken and are composed of charged species – protons and electrons – and neutral particles – the neutrons. Atoms are different for each element (or isotope) by the number of those three species. A nucleus is at the centre of the atom and is […]

Chapter 1b: Atomic theory and nuclear reactions

Atomic theory At the end of the XIX, it was known that the elements were made of one atom, unbreakable and different for each element. The masses of the atoms were known for several elements but their composition was still a mystery. Michaël Faraday discovered that atoms were in fact composed of charged species, even if […]