Daniel Iyamuremye

Before we leave this 1st section, let me ask you a question. You have certainly encountered in textbooks or newspapers the following two expressions: Chemical substances and chemical species, do these express the same reality or not? Justify your answer and if necessary illustrate

We see or use many substances on a daily basis, but rarely those substances are pure substances (chemically).  Most of the time, we rather have mixtures; natural or man-made. Questions: Explain what a mixture is, in comparison with a pure substance, and illustrate by

As a Chemist, how do you define a pure substance? How many categories of pure substances exist? Name them and explain the differences between those categories. Do those categories have sub-categories? Explain Given the following pure substances: He, Na2O, Cl2, Au, NaCl, H2CO3. Classify

Explain the Relative Atomic Mass (ram), symbol Ar, and the Relative Molecular Mass? Solution: a) The relative atomic mass or weight is defined as the ratio of the average mass of the naturally occurring isotopes of a chemical element to 1/12 of the

Write the chemical formulas of the following compounds, given the valences and the oxidation states (between brackets) of their component elements, and name them. Compounds made of: Boron (3) and Hydrogen (1) Phosphorus (5) and Chlorine (1) Hydrogen (1) and Sulfur (2) Carbon (4)

Notice: The following problems 11 to 14 are direct application of the notions and principles developed in problem 10. I would advise you to do them, by yourself or with colleagues, in order to evaluate how deep your understanding of those notions and principles

Metallic Bond Contrary to the covalent bond where there is sharing of pairs of electrons between 2 atom nuclei, in metallic bonding, all atoms in the whole body of the metal put together their valence electrons. The metallic bond then results from the attraction

Ionic Bond Ionic bond is formed between two atoms with very big difference in electronegativity. Generally,  it is agreed that a bond is ionic when the difference of electronegativity between the two atom is ΔEN >1.7. This occurs for example when a

Intermolecular Forces Up to now we have discussed about chemical bond or the force that binds atoms together within a molecule, that force is also called intramolecular force. The force that holds molecules together in a covalent pure substance or compound is called intermolecular

Covalent Bond A. G.N. Lewis, an American physical chemistry is known for his discovery, in 1902, of the covalent bond. He introduced the idea known as the octet rule, where he stated that: “A molecular structure is most stable when each atom in

Develop an explanation on how substances are formed. In that development, explain and use examples to illustrate: Why and how atoms combine? The concept of molecular orbitals The concept of hybridization of atomic orbitals and why? The origin of different properties of substances: gas,

Questions: Explain what is the Ionization Energy (IE) and the Electron Affinity (EA) of an atom? Given the following grouping of chemical elements, compare their first IE and justify: i. Na, Cl, S, Ar ii. Be, Ca, Ba Given the value of first IE

Questions: 1. In a brief historical development, explain the origin or reasons that led to the creation of the periodic table of chemical elements. 2. Explain which principle(s) or criteria the modern periodic table of chemical elements is built on, and its subdivisions.

Dear Users, Visitors, Teachers and Students, I thank you for using and visiting this blog, Chemistry Basics. I would like to talk briefly about Curiosity. As explained in the first post, Learning Chemistry, A Practical Approach, I explained the methodology adopted, that consists of

You are a teacher or a student in chemistry; you are talking to a student or a friend about Quantum Mechanics, trying to explain to him/her the concept of quantization of energy /orbits and orbitals. Question: What example(s) or analogy in real