general chemistry_lec.1.pdf

GENERAL CHEMISTRY Lec.1 ASST.LECTURE.AYAD J. DHULKEFL Chemistry: Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Matter: Is as anything that has both mass and volume.Matter is anything made of ato...

GENERAL CHEMISTRY Lec.1 ASST.LECTURE.AYAD J. DHULKEFL Chemistry: Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Matter: Is as anything that has both mass and volume.Matter is anything made of atoms and molecules. Ex.Trees, air. States of matter: Chemists classify matter into four different states; 1 solid : has a definite volume, a definite shape, and is rigid. 2 liquid : has a definite volume but no definite shape. 3 gas : has no distinct volume. 4 plasma: like a gas, plasma does not have definite shape or volume. Properties of matter 1- chemical property: properties that do change the chemical nature matter and describes a substance and its ability to change into a new substance with different properties such as flammability and ph. 2- physical properties :properties that do no change the chemical nature of matter and categorized as either intensive or extensive. *intensive : properties that do not depend on the amount of the matter present such as color, odor,conductivity, hardness melting,freezing,boiling and density. *extensive : properties that do depend on the amount of matter present such as mass ,weight ,volume and length. Composition of Matter: 1. elements : a matter that is made up of the same kind of atoms. 2. compounds : is composed of two or more combined elements of different kinds that are combined. 3. mixture : material that is made up of 2 or more substances that can be separated physically. Atom: the smallest unit of an element having the chemical properties of the element, and consisting of a dense, central, positively charged nucleus surrounded by a system of electrons. an atom itself is composed of three types of subatomic particles: the proton, neutron, and electron. The protons and the neutrons make up the center of the atom called the nucleus; this small nucleus is surrounded by orbiting electrons. the electrons carry a negative charge and the protons carry a positive charge, while neutrons have no charge. in a normal (neutral) atom the number of protons and the number of electrons are equal. often, but not always. Atomic number (z) (also known as the proton number) is the number of protons found in the nucleus of an atom, in an atom of neutral charge, the atomic number is also equal to the number of electrons. atomic number= number of proton=number of electron Mass number (a) also called atomic mass number or nucleon number, is the total number of protons and neutrons in an atomic nucleus. the mass number is different for each different isotope of a chemical element. Chemical bond: is an attraction between atoms that enables the formation of chemical substances that contain two or more atoms or the forces that hold atom together in compounds. 1- ionic bond: bond in which one or more electrons from one atom are removed and attached to another atom.force between metals and non metals, resulting in positive and negative ions which attract each other. 2- covalent bond: bond in which one or more of electrons are shared by atoms. covalent chemical bondsinvolve the sharing of a pair of valence electrons by two atoms. 3-coordinate covalent bond: (also called a dative bond) is formed when one atom atom shares a pair of electrons with another atom lacking such a pairto form a single covalent bond. 4-hydrogen bonding: it is a force of attraction between a hydrogen atom in one molecule and atom of high electronegativity having a free electron pair in another molecule (f,n,cl). METALLIC BOND is is a type of chemical bonding that rises from the electrostatic attractive force between conduction electrons and positively charged metal ions.  Periodic table: The periodic table lists all of the elements in order of their atomic numbers. Groups or families: the modern periodic table of the elements contains 18 groups groups in the periodic table of elements: 1-S orbital groups: 1_alkali metals (li, na, k, cs, fr). *one loosely bound valence electron *less dense than other metals *highly reactive *low ionization energy *low electronegativity 2-alkaline earth metals ( be, mg, ca, sr, ba, ra). *two electrons in the valence shell *readily form divalent cations *low electron affinity 2-P Orbital Groups: *metalloids or semimetals (b ,si, ge ,as, sb ,te , po) *electronegativity and ionization energy intermediate between that of metals and nonmetals hardness, conductivity. 3-D and f Groups: transition metals the lanthanides (rare earth) and actinides are also transition metals. *very hard, usually shiny. *high melting and boiling points *high thermal and electrical conductivity. The Halogens And Noble Gases Are Nonmetals, Although They Have Their Own Groups, Too. 1-halogens :-(F, Cl, Br, I, At) *The Halogens Exhibit Different Physical Properties From Each Other But Do Share Chemical Properties. *Very Reactive. *High Electronegativity. 2-noble Gases( He, Ne, Ar, Kr, Xe, Rn( The Noble Gasses Have Complete Valence Electron Shells, So They Act Differently. *Unreactive. *Very Low Electronegativity. Methods of analysis: Is the study of separation, identification and quantification of the chemical components in a sample of matters. It is divided into two parts: 1- Qualitative analysis: gives an indication for the identification of elements or grouping of elements present in a sample. 2- Quantitative analysis: determines the amount or percentage of one or more of constituents of a sample Solution: A homogeneous mixture of two or more substances, which may be solids, liquids, gases. The particles of one or more substances (the solute) are distributed uniformly throughout another substance called (the solvent(. Saturated Solution: Is a solution in which the solvent cannot dissolve any more solute to increase the concentration of the solution. Any more solute added will sit as crystals on the bottom of the container. Concentrated solution: Is one which contains a large amount of solute per unit volume of solution. Dilute solution: Is one which contains a small amount of solute per unit volume of solution. THE END