Chemistry Lecture Notes PDF

Atoms and atomic theory Democritus -Greek philosopher -name the smallest piece of matter “atomos” mean (not to be cut) -democritus Thatoms were small hard particles that were all made of same material, but we’re different shape and sizes -atoms were infinite in number DALTON ATOMIC THEORY -All...

Atoms and atomic theory Democritus -Greek philosopher -name the smallest piece of matter “atomos” mean (not to be cut) -democritus Thatoms were small hard particles that were all made of same material, but we’re different shape and sizes -atoms were infinite in number DALTON ATOMIC THEORY -All matter is made of atoms -atoms of a given element are identical in mass and properties -atoms have given element are different from those of any other element -Chemical reaction is a rearrangement of atoms HISTORY,THEORIES AND MODEL OF AN ATOM JOHN DALTON(1803) -the word Atoms comes from the greek word “atomos” meaning “indivisible” -his theory stated that atoms are indivisible - elements are identical -compounds are combination of different types of atoms JJ Thompson(1904) - (plum pudding model)-it shows that atoms are composed of electrons scatter throughout the spherical cloud of positive charge - he discovered electrons Ernest rutherford(1911) - (nuclear model) -quantum mechanical model, electrons occupy specific energy levels/shells in an atom. The number of electron in each level is governed by the formula 2n^2 1st shell-2 electrons 2nd shell-8 electron 3rd shell - 18 electrons -realize positive charge was localized in the nucleus of an atom Neil bohr(1913) -(planetary model) - bohr model passively charge protons and neutral neutrons are tightly held in the nucleus or center of the atoms -he modified ratherford model of the atom by stating that electrons move around the nucleus in orbits are fixed sixes and energies Erwin Schrodinger (1926) -he stated that elections do not move in set paths around the nucleus but in waves -his model was the most accurate model of the atom Properties of protons electrons and neutrons Electrons -negatively charge -Located around the nucleus Proton -Positively charge -Located in the nucleus Neutron -no charge -located in the nucleus Isotopes -Atoms with same proton, but different number of neutron Isotopes notation -It includes additional information about an isotope, mass number and atomic number are included Mass number -number of nucleons in nucleus Atomic number -number of protons in a nucleus 3 main isotopes -tritium -deuterium -protium ELECTRONS Valence Electrons-electrons in the outermost ring THE AUFBAU PRINCIPLE -(meaning building up) used to determine the electronic configuration of the atom or ion HUND’S RULE MAXIMUM MULTIPLICITY  PAULI EXCLUSION PRINCIPLE -“ no 2electrons in an atom can have the same set of all four quantum numbers” QUANTUM NUMBERS -specify, the properties of atomic orbitals and their electrons FOUR QUANTUM NUMBERS principal quantum number (n) -indicates main energy levels Orbital quantum number (l) -indicate shape or orbital sub levels S-0 P-1 D-2 F-3 Magnetic quantum number (ml) -indicates the orientation of the orbital in space Ex.- (ml=2 therefore -2,-1,0,1,2) Spin, quantum number (ms) -Indicates the speed of the electron clockwise or counterclockwise values of +1/2 or -1/2 Fundamental chemical laws Antoine Lavoiser -regarded measurement as the essential operation of chemistry Law of conservation of mass -1stablish the basis for the breakthroughs in chemistry -mass is neither created nor destroyed in chemical reaction Law of definite proportions Joseph proust -Showed that a given compound always contains exactly the same proportion of element by mass Law of definite proportion Iven compound always contain exactly the same proportion of element by mass John dalton He believed that since each element was made up of a small number of distinct particles, a particular compound should always contain the same set of atoms Law of multiple proportions -the law of multiple proportion when 2 elements form a series of compounds the ratios of the masses of the second elements that combined with 1 g of the first element can always be reduced to small whole number Properties of matter Matter -anything that occupies space and has mass -The stuff of the universe, air glass planets, students anything that has mass and volume Composition of matter -the types and the amount of simpler substances that make it up Substance -is a type of matter that has defined fixed composition Properties-the characteristics that give each substance its unique identity Physical properties -substance show by itself without changing into or interacting with another substance Physical change-occurs ,when substance alters its physical form, not its composition Chemical properties -Those substance that show as it changes into our interacts with another substance 3 STATES OF MATTER SOLID -has fixed sheep and does not conform to the container shape -particles are close together and organized LIQUID -confirms to the container shape, but fill the container only to the extent of the liquids volume -particles are close together but disorganized GAS -conform to the container shape also but it feels the entire container and thus , does not form a surface -particles are far apart and disorganized Extensive properties -depends on the quantity of matter observed Intensive properties -independent of the amount of matter observed Chemical elements -substance made up of only a single type of atom Chemical compounds -substance in which atoms of two or more different elements are combined with one another Molecules -the smallest entity, having the same proportions of the constituent atoms as does the compound as a whole Mixtures -can be separated into pure substances by physical methods Pure substances -One with constant composition Homogeneous mixture -uniform in composition and properties throughout a given sample, but variable from one sample to another Aqueous Solutions in water Heterogeneous mixture -components, separate into distinct regions Measurement -the comparison of a physical quantity to be measure with the unit of measurement that is with a fixed standard of measurement Physical quantities -those aspect in the universe that can be measured by any desired unit of measurement Mass -describes the quantity of matter in an object Temperature -the degree of hardness and coldness, but necessarily a measure of heat Density -property of matter that is often used by chemist as a identification tag for a substance is density ,the mass of a substance per unit volume of the substance Dimensional analysis -a given result must frequently be converted from one system of units to another Unit factor approach -also known as dimensional analysis or dimensional modeling is the most effective approach for accomplishing this History of the periodic table Johann dobereiner -first chemist recognize pattern -found several groups of three elements that has similar properties John newlands -he suggest that elements should be arranged in octaves based on the idea that certain properties seem to repeat for every eight elements in a way similar to the music scale, which repeats for every eight tone Julius lothar meyer and Dmitri mendeleeve -mendeleeve emphasize how you spell the table could be in predicting the existence and properties of still unknown elements -they created the present form of the periodic table Two categories of elements Metals -Good conductors of heat and electricity -Malleable and ductile -Have moderate to high melting points Non metals -conductors of heat and electricity and our non-malleable solids Metalloids -elements that look like metals and in some ways behave like metals, but also have some non-metallic properties Noble gases -they are considered as the stable elements because of their complete valence shell REPRESENTATIVES ELEMENTS A group -Called representatives elements Group1A- alkali metals GroupIIA- alkaline earth metals GroupIIIA-boron family GroupIVA-carbon family GroupVA-nitrogen family GroupVIA- oxygen family GroupvIIA-halogens D transition metals -elements in the B group in the periodic table are known as the D transition elements or simply as transition metals F transition metals -Sometimes known as inner transition elements, these elements in which elections are being added to F orbitals The modern periodic table law -States that the properties of elements are function of their atomic numbers Core electrons -electrons in inner main energy levels Some atomic properties Atomic size -it is average distance between the nucleus and the outermost election Ionic radius -the average size of the atom when it has lost or electrons Ionitization energy -the energy required to remove an electron from an atom Electonic affinity -the negative of electron gain and therapy Electronegativity -the ability of an atom to attract shared electrons Metallic properties -Metallica characters increases from top to bottom and decreases from left to right with respect to position in the periodic table -non-metallic characters decreased from top to bottom and increase from left to right in the periodic table Isoelecrtric substance -substance having the same number of electrons Chemical bonds -forces that hold atoms together in a compound -atoms bond together to gain stability of a complete valence shell found in a noble gas Type of chemical bonds Ionic bond -solid with high melting points -soluble in polar solvent, such as water -most are insoluble in nonpolar solvent -molten compounds conduct electricity well because they contain mobile charge particles -aqueous Solution conduct electricity well because they contain mobile charge particles -result from the transfer of electrons usually from metal to a nonmetal -electrostatic force of attraction between opposite charge ions -They are often formed between two elements with quite different electron activities usually a metal and a nonmetal Covalent bond -result from the sharing of electron usually between two nonmetal -electrostatic force of attraction between shared electrons and the nuclei sharing the electrons -They are liquids are solid with low melting point -Many are soluble in polar solvent -Most are soluble in a nonpolar solvent -Liquid and molten compound do not conduct electricity -aqueous solutions are usually poor conductors of electricity because most do not contain charge particles -They are often formed between two elements with similar electronegativities usually nonmetals Lewis structure -representation of covalent bonding based on lewis symbol Resonance structure -possible lewis structure of a molecule or a polyatomic ion, but not one of which is fully consistent with the observed properties of the molecule in ion Formal charge -the difference between the number of valence electron that atom has in the free neutral state, and the number of valence electron, and the atoms appeared to possess in the bonded state