Lecture1-General+Chemistry+Prof.+OUCHBANI_2022-2023.pdf

GENERAL CHEMISTRY Lecture1 Module: Chemistry/Biochemistry Academic Year : 2022-2023 www.um6ss.ma Prof. Tarik OUCHBANI 1  PLAN Chapter I:...

GENERAL CHEMISTRY Lecture1 Module: Chemistry/Biochemistry Academic Year : 2022-2023 www.um6ss.ma Prof. Tarik OUCHBANI 1  PLAN Chapter I: Structure of Matter Chapter II: Model of the atom Chapter III: Chemical bonds Chapter IV: Chemistry in solutions Chapter V: Oxidation/Reduction (redox) reactions  Chapter I Structure of Matter On Earth, matter appears in three clearly defined forms—solid, liquid, and gas— whose visible and perceptible structure is a function of behavior that takes place at the molecular level. Though these are often referred to as "states" of matter, it is also useful to think of them as phases of matter. This terminology serves as a reminder that any one substance can exist in any of the three phases. Water, for instance, can be ice, liquid, or steam; given the proper temperature and pressure, it may be solid, liquid, and gas all at once. matter is made up of atoms that combine into molecules and crystals. To understand how molecules and crystals form and the properties of macroscopic matter, we need to go more deeply into atomic structure. The key ideas we will need to know are as follows: Atoms are made up of electrons and nuclei; The sizes of atoms are determined by the distribution of the atom's electrons; The nuclei are small but contain almost all of the mass of the atom; The bonding between atoms that builds molecules and crystals arises from the electrical forces between the electrons and nuclei and the sharing of electrons between different atoms. The electron is a stable particle, negatively charged, characterized by: ü Charge : qe= -1.602.10-19 Coulomb üMasse : me= 9.109. 10-31Kg (Coulomb is the unit of electric charge) The nucleus The nucleus is made up of stable elementary particles called nucleons which can occur in two forms in the free state: the proton and the neutron. a) The proton is a positively charged particle. It is characterized by a: Charge : qp =1.602.10-19 Coulomb Masse : mp = 1.673.10-27 Kg = 1836 me b) The neutron is an electrically neutral particle with a mass roughly equal to that of the proton. Charge : qn = 0.00 Coulomb Masse : mn = 1.675.10-27 Kg = 1839 me A: the mass number. It designates the number of nucleons which is the sum of the number of protons and the number of neutrons. Z: is called the atomic number or charge number (protons or electrons), it characterizes a given atom, that is to say a determined element.  IDENTIFICATION OF CHEMICAL ELEMENTS Exemple : THE ISOTOPES  ATOMIC MASS The atomic mass of a chemical element is: ü the mass of one mole of an atom ü the mass of a gram atom ü the atomic molar mass ü the mass of ƝA atoms ƝA being the number of AVOGADRO equal to 6,023.1023 mol-1 Application : We calculated the real mass of the Carbon atom MC= 20.088 10-27 Kg The atomic Molar mass of the Carbon is : ƝA x MC = 12.09 g/mol  ATOMIC MASS There are two scales: ü The scale of atomic mass expressed in units of atomic mass (a.m.u). ü The atomic molar mass scale expressed in grams. The reference term being carbon 12. By definition : The atomic mass unit (a.m.u) is the twelfth the mass of the carbon 12 atom (i.e. whose nucleus has 6 protons and 6 neutrons). 1u.m.a = (1/12).mc  ATOMIC MASS ü The molar mass of the Carbon atom is 12 a.m.u The atomic mass of carbon corresponds to the mass of 6,023.1023 carbon atoms. ü One mole of carbon atom weighs 12g. 12g = ƝA atoms 12g = 6,023.1023.12 1 a.m.u =12g /6,023.1023.12 =1/6,023.1023 g = 1,663.10-24g 1 a.m.u. = (1/ Ɲ) g The relative abundances of the stable isotopes of elements commonly used ATOMIC MASS DEFECT  ATOMIC MASS DEFECT Mass of protons mp= 1836 me Mass of neutron mn= 1839 me, Mass of electron (me) = 9.109. 10-31Kg Mass of protons (mp)= 1,673 10-27Kg Mass of neutron(mn)= 1,675 10-27Kg mNucleus is always