Tiêu đề Material - General Chemistry.docx ✅

SPECIAL TOPICS III GENERAL CHEMISTRY Chemistry – branch of science which deals with the study of matter and the changes it undergoes (Chemistry is also known as the central science) Branches of Chemistry:  Organic Chemistry – Study of compounds with carbon elements in it  Inorganic Chemistry – Study of compounds with non-organic elements  Physical Chemistry – Study of theoretical aspects of structures and changes in matter  Analytical Chemistry – Study with the analysis of different substances  Biochemistry – Study of biologically important elements of chemistry Matter – Anything that occupies space and has mass. States of Matter: Solid – Particles that are tightly packed and have regular arrangement Liquid – Particles are tending to hold and usually hold the shape of its container Gas – Particles are dispersed and loosely packed Has Definite Shape Has Definite Volume Solid ס ס Liquid X ס Gas X X Plasma – Ionized gas whose energy is sufficient to release atoms Bose-Einstein Condensate – Occurs at very low temperature in which particles tend to stop from moving Properties of Matter: (Property – Characteristics that differentiates a substance from other substances) Intrinsic/Intensive Property – Property that is independent (not affected) to its size or mass Examples: Temperature, Pressure, Density Extrinsic/Extensive Property – Property that is dependent (affected) to its size or mass Examples: Length, Mass, Volume Physical Properties – Property that is measured without being changed/destroyed/lose identity Examples: Length, Density, Boiling Point Chemical Properties – Property that is changed/destroyed/lose identity when measured Examples: Corrosiveness, Oxidation Level Heat Changes of Matter: Exothermic Change – Change that releases heat/energy during the process Endothermic Change – Change that absorbs heat/energy during the process Phase Changes in Matter To Solid To Liquid To Gas To Plasma From Solid Melting or Fusion Sublimation (Not Possible) From Liquid Solidification or Freezing Evaporation or Vaporization (Not Possible) From Gas Deposition Condensation Ionization From Plasma (Not Possible) (Not Possible) Recombination
Property Change: Physical Change – Change that retains its form/identity Chemical Change – Change that transforms the identity/composition Classifications of Matter: Pure Substance – Matter with definite composition Types of Pure Substances:  Element – Substance that only contains one type of atom  Compound – Substance that contains two or more elements that are chemically combined Properties of Pure Substances:  Has a definite/fixed boiling point and freezing point  Has a uniform and constant structure Mixture – A combination of two or more substances Types of Mixtures  Homogeneous – properties are uniform throughout the material  Heterogeneous – compositions are identifiable or visible Classification of Mixtures  Solutions – A homogeneous mixture. Contains a solute and solvent.  Colloid – A heterogeneous mixture with very fine particles incorporated  Suspensions – A heterogeneous mixture with larger particles incorporated Quantitative Laws of Matter: Law of Definite Proportion  states that the different samples of the same compound contain its constituent element in the same proportion by mass Law of Multiple Proportion  states that if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in the ratios of small whole numbers Law of Conservation of Mass  states that matter can neither be created nor destroyed. Law of Conservation of Energy  states that energy can neither be created nor destroyed. It can be only transformed from one form to another Particle – The small, localized part of Matter Atom – The smallest particle of an element Molecule – The smallest particle in a compound Substance Particle Uses the terms Element and Compound Uses the terms Atom and Molecule The SI unit for mass is kilogram The unit for mass is atomic mass unit (amu) Macroscopic in nature Microscopic in nature Uses Mole as the amount of substance Uses Molecule as the amount of substance According to Democritus, all matter consists of very small, indivisible particle called ATOMOS Ions are atoms with given electron charge A cation is a positively charged ion. It gives electron/s in the process An anion is a negatively charged ion. It receives electron/s in the process Electrodes – solid conductors that establishes an electrical connection to non-conductive materials Anode – the positively charged electrode by which electrons enter Cathode – the negatively charged electrode by which electrons enter
Dalton’s Atomic Theory (John Dalton, 1803) 1. Elements are composed of extremely small particles called atoms. 2. All atoms of a given element are identical, having the same size, mass, and chemical properties. The atom of one element is different from the atoms of all other elements. 3. Compounds are composed of atoms of more than one element. In any compound, the ratio of the number of atoms of any two elements present is either an integer or a fraction. 4. A chemical reaction involves the separation, combination, or rearrangement of atoms. It does not result in their creation or destruction. Electron  It is the negatively charged particle that dictates the charge of the atom and was discovered by Joseph John Thomson. It has a relative charge of -1  [Thomson model of the atom] An atom consists of a (positively charge) jelly like mass with (negative charge) electrons scattered through it known as plum-pudding model.  Robert Millikan found the charge of an electron to be –1.6022 x 10 -19 C (coulombs) from his oil drop experiment. Proton  It is a positive charge particle of an atom that describes what the atom is and was discovered by Ernest Rutherford. His research resulted in a nuclear reaction which led to the first 'splitting' of the atom. It has a relative charge of -1  [Rutherford model of the atom] Also known as the planetary model, which introduces a nucleus known as a Nucleon, which the electrons orbiting  Later after this discovery, it is also found that the charge of a proton to be 1.6022 x 10 -19 C (coulombs) Neutron  It is neutrally charged particle that helps dictates the total mass of an atom and was discovered by James Chadwick. It has no charge  It is also James Chadwick who retrospect the masses of each subatomic particle using his Berrylium Bombardment Experiment Atomic Values of Elements  Atomic number (Z) – The number of protons determines an element’s atomic number. In a neutral atom the number of protons is equal to the number of electron.  Mass number (A) – The total number of neutrons and protons present in the nucleus of an atom of an element.  Atomic Mass – The sum of the masses of its isotopes, each multiplied by its natural abundance Terms in Atoms  Isotopes – are atoms of the same element with different numbers of neutrons in their nuclei  Isomer – are molecules of the same elements but different structure  Isobar – are atoms of different element but same atomic weight
Periodic Table Periodic table is a chart in which elements having similar chemical and physical properties are grouped together. It was developed by Dmitri Mendeleev and Lothar Meyer. The elements are arranged by increasing atomic number in horizontal rows called period and in vertical column known as groups or families. The elements can be divided into three categories: 1. A metal is a good conductor of heat and electricity 2. A nonmetal is usually a poor conductor of heat and electricity. 3. A metalloid has properties that intermediate between those metals and nonmetals. Periodic law - states that when the elements are arranged in the order of increasing atomic number, elements with similar properties appear at periodic interval. This law gives the rules for periodic trends. Elements are often referred to collectively by their periodic table group number. The following are their common names: - Group IA (Alkali metals) - Group IIA (Alkaline Earth metals) - Group IIIA (Triels/Icosagens) - Group IVA (Tetrels/Crystallogens) - Group VA (Pentels/Pnictogens) - Group VIA (Chalcogens) - Group VIIA (Halogens) - Group VIIIA (Noble gases/Aerogens) - Group IB to XB (Transition metals) - Elements along Lanthanum (Lanthanides) - Elements along Actinium (Actinides) Periodic Trends  Atomic radius (atomic size) which is one-half the distance between the two nuclei in two adjacent atoms  Ionic radius which is the radius of an ion of a given element. It has the same periodic trends as the atomic radius  Ionization energy refers to the amount of energy needed to remove an electron from an atom  Electron affinity is a measure of the tendency of an atom to gain electron