periodic table of the elements-元素周期律

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,Periodic Table of the elements,2015.12.21,What is the Periodic Table of The Elements?,Dmitri Mendeleev,was the first scientist to create a periodic table of the elements similar to the one we use today. You can see,Mendeleevs original table,(1869). This table showed that when the elements were ordered by increasing,atomic weight, a pattern appeared where properties of the elements repeated,periodically,. This periodic table is a chart that groups the elements according to their similar properties.,The history of the development of the periodic table of elements,1.The Beginnings of the Periodic Table,Before written history, people were aware of some of the elements in the periodic table. Elements such as gold (Au), silver (Ag), copper (Cu), lead (Pb), tin (Sn), and mercury (Hg).,It wasnt until 1649, however, until the first element was discovered through scientific inquiry by,Hennig Brand,. That element was phosphorous (P).,By 1869, 63 elements had been discovered.,Between 1817-1829,Johann Dobereiner,began to group elements with similar properties in to groups of three or triads.,The history of the development of the periodic table of elements,2.Precursors to the Periodic Table,In 1862,A.E.Beguyer de Chancourtois,was the first person to make use of atomic weights to reveal that the elements were arranged according to their atomic weights with similar elements occurring at regular intervals.,In 1863, John Newlands, an English chemist, proposed the Law of Octaves which stated that elements repeated their chemical properties every eighth element.,The history of the development of the periodic table of elements,The Fathers of the Periodic Table,Lothar Meyer,and,Dmitri Ivanovich Mendeleev,independently produced remarkably similar versions of the periodic table of elements at the essentially the same time.,Mendeleev,periodic table appeared in his work,On the Relationship of the Properties of the Elements to their Atomic Weights,in 1869.,The thinking of giant,when elements are listed according to,the atomic mass, some properties occur periodically,Actual version: listed according to,the atomic number,Intuition: some element were still to be discovered!,The thinking of giant,Valence,: old definition, replaced by others like oxidation number,Here: the number of H atoms linked to the element:,H = 1 (H2); He = 0; Li = 1 (LiH); Be = 2 (BeH2); B = 3 (BH3); C = 4 (CH4); N = 3 (NH3); O = 2 (H2O); F = 1 (HF), etc.,The history of the development of the periodic table of elements,3. The Modern Periodic Table,Glenn Seaborg,discovered the transuranium elements, atomic numbers 94 to 102.,Dr. Seaborg and his colleagues are also responsible for the identification of more than 100 isotopes of elements.,The history of the development of the periodic table of elements,List the elements horizontally, go to a new line when a noble (rare) gas is found, place elements with similar behaviour in columns!,The history of the development of the periodic table of elements,Blocks have dimension L,L = 2, 6, 10, 14 = 2 x (2 l + 1),l = 0, 1, 2, 3 ,Why?,Quantum Mechanics explain this fundamental finding,The factor 2 arises from two possible orientations of,the electron spin,(duplicity),The term 2 l + 1 arises from the multiplicity of,the angular quantum number,l, going from l to +l (,Magnetic quantum number,),the basic,trends of the Periodic,Table,atomic radius of the isolated atom,metallic/non-metallic character of the element,tendency to give molecules in the elemental state,electron affinity of the isolated atom,ionization potential of the isolated atom,electronegativity (defined for an atom in abond: see below),chemical reactivity of the element,What is on the Element Key?,Each square on the periodic table gives information about an element. On many printed periodic tables you can find an elements,symbol,atomic number, and,atomic weight,.,Periods and Groups,Elements in the periodic table arranged in periods (rows) and,groups,(columns). Atomic number increases as you move across a row or period.,Rows of elements are called periods. The period number of an element signifies the highest unexcited energy level for an electron in that element. The number of elements in a period increases as you move down the periodic table because there are more sublevels per level as the energy level of the atom increases.,Periods,Groups,Columns of elements help define element groups. Elements within a group share several common properties. Groups are elements have the same outer electron arrangement. The outer electrons are called valence electrons. Because they have the same number of valence electrons, elements in a group share similar chemical properties. The Roman numerals listed above each group are the usual number of valence electrons. For example, a group VA element will have 5 valence electrons.,The,atomic radius is defined for the isolated atom,(not always easy toisolate!),describes the size of the spherical electronic cloud around the nucleus,depends on Z,Also defined for ions,(ionic radii),Decrease for loss of electrons, increase for gain,First ionization energy (I.E.),is the energy required to extract one electron from the isolated atom. Successive ionization energies are also possible.Measures the tendency of an isolated atom to loose electrons,I.E. decreases with increasing Z,Variation of the first ionization energy along groups and periods of the periodictable,Electron affinity A,is the energy released when an isolated atom captures one electron (so measuring the tendency the isolated atom has to attract electrons),Variation of the electronic affinity along the groups and periods of the periodic table,Electronegativity:,propertyof an atom in a molecule to attract electrons of an other atom it binds to A typical atomic property!,Is a measure possible?,Mulliken,definition: the average between first I.P. and Electron Affinity. Compromise between tendency to donate and tendency to acquire electrons!,Pauling,definition: considering two atoms X and Y, the difference in bond energy between X-Y and the average of X-X and Y-Y gives an other estimate of electronegativity.The two scales mostly COINCIDE! Remarkable fact!,EN can be considered as a measurable quantity, of the potential type(one reference value must be fixed).,Electronegativity and periodic table,Regular trend of EN along the table:,-most electronegative: F (fluorine),-next most: O, N, Cl,-least electronegative: Cs,Rb,Consider,a diatomic molecule X-Y,: bond electrons will be displaced towards the more electronegative atom.,If the difference in EN is large(say 2), the molecule is very polar and becomes unstable(ionic infinite structures are preferred!): solid NaF is constituted by Na,+,cations and F,-,anions.,Electronegativity is fundamental to define oxidation numbers!,Entirely ionic structures are helpful for determining oxidation numbers, very useful in balancing equations and indicative of redox processes,Oxidation number,is the charge (real or apparent) given to an atom in a totally ionic structure,Simple ions have ON equal to the charge they carry: e.g. Cl,-, Ca,2+,In compounds, ON is the charge each element would assume if electrons were on the more electronegative atom in a bond.,Arrow indicates the more electronegative atom,Rules for ON,1.,Elements have ON = 0,2.,Fluorine, the most electronegative elements has always ON = - 1 (if not element),3.,In most compounds Oxygen (the second most electronegative element) has ON = -2. Exceptions: i) peroxides, where Oxygen has ON = -1; ii) OF,2, where Oxygen has ON +2.,4.,In most compounds, Hydrogen has ON = +1. Exception: metal hydrides where Hydrogen has ON = -1,5.,In compounds, alkali metals have always ON = +1,6.,In compounds, alkali-earth metals (metallialcalino-terrosi) have always ON = +2,7.,The algebraic sum of ONs: i) in an ion is equal to the total charge of the ion; ii) in a molecule is zero.,Fundamental compounds in inorganic chemistry,Periodic Table,Non metals,Transitional,metals,Metalloids,Rare Earth,Halogens,Other metals,Alkaline Earth,Nobel Gasses,Alkaline earth Metals,H,hydrogen,Li,lithium,Na,sodium,K,potassium,Rb,rubidium,Cs,caesium,Fr,francium,Be,beryllium,Mg,magnesium,Ca,calcium,Sr,strontium,Ba,barium,Ra,radium,Sc,scandium,Y,yttrium,Ti,titanium,Zr,zirconium,Hf,hafnium,V,vanadium,Nb,niobium,C,r,chromium,Mo,molybdenum,Mn,manganese,Tc,technetium,Fe,iron,Ru,ruthenium,Co,cobalt,Rh,rhodium,Ni,nickel,Pd,palladium,Cu,copper,Ag,silver,Zn,zinc,Cd,cadminium,Ta,tantalum,W,tungsten,Re,rhenium,Os,osminium,Ir,iridium,Pt,platinum,Au,gold,Hg,mercury,B,boron,Si,silicon,Ge,geramanium,As,arsenic,Sb,antimoney,Te,tellurium,Po,polonium,C,carbon,P,phosphorous,N,nitrogen,O,oxygen,S,sulphur,Se,selenium,Al,aluminium,Ga,galium,In,indium,Tl,thallium,Sn,tin,Pb,lead,Bi,bismuth,F,fluorine,Cl,chlorine,Br,bromine,I,iodine,At,astatine,He,helium,Ne,neon,Ar,argon,Kr,krypton,Xe,xenon,Rn,radon,Lanthanide,Series,(rare earth),Actinium,Series,1,2,3,11,19,37,55,La,Lanthanum,Ce,cerium,Pr,praseodymium,Pm,promethium,Sm,samarium,Eu,europium,Gd,gadolinium,Tb,terbium,Dy,dysprosium,Ho,holmium,Re,erbium,Tm,thulium,Yb,ytterbium,Lu,lutetium,Nd,neodymium,Ac,actinium,Pa,protactinium,U,uranium,Np,neptunium,Pu,plutonium,Am,americium,Cm,curium,Bk,berkelium,Cf,californium,Es,einsteinium,Fm,fermium,Md,mendelevium,Th,thorium,No,nobelium,Lr,lawrencium,87,4,12,20,38,56,88,39,22,21,40,72,23,41,73,24,42,74,25,43,74,26,44,76,27,45,77,28,46,78,29,47,79,30,48,80,31,49,81,5,13,32,50,82,6,14,33,51,83,7,15,34,52,84,8,16,35,53,85,9,17,36,54,86,10,18,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,Representative vs. Transition Elements,There are two sets of groups. The group A elements are called the representative elements. The group B elements are the nonrepresentative elements.,Classifying Elements,Nonmetals,The nonmetals are poor conductors of heat and electricity. Solid nonmetals are brittle and lack metallic luster. Most nonmetals gain electrons easily. The nonmetals are located on the upper right side of the periodic table, separated from metals by a line that cuts diagonally through the periodic table. The nonmetals can be divided into classes of elements that have similar properties. The halogens and the noble gases are two groups of nonmetals.,Metalloids,Most elements are metals. There are so many metals, they are divided into groups: alkali metals, alkaline earth metals, and transition metals. The transition metals can be divided into smaller groups, such as the lanthanides and actinides.,What are the Properties of the Metalloids?,Elements that have some properties of metals and some properties of nonmetals are called metalloids. Silicon and germanium are examples of metalloids. The boiling points, melting points, and densities of the metalloids vary. The metalloids make good semiconductors. The metalloids are located along the diagonal line between the metals and nonmetals in the periodic table.,Common Trends in Mixed Groups,Remember that even in mixed groups of elements, the trends in the periodic table still hold true. Atom size, ease of removing electrons, and ability to form bonds can be predicted as you move across and down the table.,The functions,of the Periodic,Table,Very Great Tool,reveal atomic structure,The gradient law of elements nature,The inner relationship among elements,Seek for new elements and compounds,Lifelong labor, then become a,genius-,Mendeleev,Thank you!,