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 […]
Posts in the 1st Year category:
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 1d: Periodic table of elements
The table of Mendeleev is also called the periodic table of the elements. More than a simple list of the existing atoms. Mendeleev sorted the elements with regard to their oxidation/reduction by O/H R20 R0 […]
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 […]
Chapter 9 : Replication
1) Definition The DNA replication is one of the key mechanisms of cell cycle. It is a highly regulated biological process in which new synthesis and repair mechanisms ensure the integrity of the genome. S phase or replication phase follows the G1 phase during which the cell synthesizes all the elements necessary for this replication. […]
Chapter 3d: Reactions in organic chemistry: Nucleophilic reactions
We will now discuss the types of reactions that can be performed on organic compounds. In this first year lessons, we will only focus on one of the most used reactions: the nucleophilic substitution (SN). A substitution reaction is indeed the base of the organic chemistry: its goal is to substitute one group of a […]
Chapter 3e: Functional groups
Other than alkanes, alkenes, alkynes and halogenoalkanes, there is a large number of functional groups that can be found in organic chemistry. In this first year, we will only take a look on the richness of possibilities that organic chemistry allows through the functional groups a carbohydrate chain can wear, and of some of their […]
Chapter 3b: cycloalkanes
Cycloalkanes A cycloalkane is, as it name shows, a cyclic alkane chain. Each carbon of the chain is bound to (at least) two carbons and two hydrogen’s. The general formula is thus CnH2n and the name of the compound is the same name as the corresponding alkane with the prefix cyclo. Cyclopropane The smallest cycle, […]
Chapter 3c: alkenes and alkynes
Alkenes Alkenes are organic compounds made of carbons and hydrogens. Opposite to alkanes, which have the same components, the general formula of alkenes is not CnH2n+2. Into an alkene, two carbons are bound by a pi liaison (also called double liaison). The smaller alkene is the ethene CH2=CH2. To make this liaison, each carbon shares […]