The periodic table & periodic law

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Unit 5

Transcript of The periodic table & periodic law

  • 1.The Periodic Table & PeriodicLaw

2. Objective: Trace the development of the periodic table Identify key features of the periodic table 3. Sheldon & The Element Song 4. Development of the periodic table - John Newlands - Meyer and Meedeleev 5. John Newlands 1864 English chemist -Proposed a scheme for the elements -He noticed that when elements where arrangedbased on atomic mass their properties repeatedevery 8th element. 6. John Newlands -Newlands named the periodic relationship Lawof octaves. (after a musical, a name which wasfrowned upon because it was unscientific) -Although not accepted Newlands correct in theaspect that elements do repeat each other. 7. Meyer & Mendeleev Meyer-Russian chemist-1869 Dmitri Mendeleev- 1869 Demonstrated a connection between atomic mass and elemental properties. 8. Meyer Demonstrated a connection between atomic mass and elemental properties Arranged the elements in order of increasing atomic mass 9. Mendeleev Demonstrated a connection between atomic mass and elemental properties Arranged the elements in order of increasing atomic mass Predicted the existence of properties of undiscovered elements. 10. Mendeleev Mendeleev is given more credit. History of the Periodic Table 11. Periodic Table Activity Recognizing patterns 12. What did Mendeleev miss? New elements were discovered, it became evident that the periodic table was not in the correct order. Henry Moseley (1887-1915), arrange elements by atomic number. 13. Moseley Discovered that atoms contain a unique number of protons called the atomic number Arranged element in order of increasing atomic number, which resulted in a periodic pattern of properties. 14. The Periodic Law Atoms with similar properties appear in groupsor families (vertical columns) on the periodictable. They are similar because they all have the samenumber of valence (outer shell) electrons, whichgoverns their chemical behavior. 15. The Periodic Table & PeriodicLawElements & Modern periodic table 16. Element Song 17. Modern Periodic Table Groups= columns Vertical Periods= rows horizontal Periodic properties Periods have similar characteristics. 18. Metals, Nonmetals, Metalloids How can you identify a metal? What are its properties? What about the less common nonmetals? What are their properties? And what the heck is a metalloid? 19. Alkali Metals Li Na K Rb Cs Fr 20. Alkali Metals 1 valance electron very reactive Alkali metals with water 21. Alkali metals Very reactive, often exists as compounds with other elements Two familiar alkali metals are..Na- used in table saltLi- Used in batteries 22. Alkaline Earth 2 valanceelectron Reactive-formsoxides Important inliving things Found onplanet in rawforms 23. Halogens Not super stable 7 valance electrons Need 1 more 24. Halogens Cl- HalogenUsed as a gasin WWI 25. Noble Gases Most un-reactive Why? 8 valance electrons 26. Inert gases Is a gas which does not undergo chemical reactions under a set of given conditions Mig welder- uses argon 27. CHNOPSS-nonmetals important to life Carbon- thats what we are made of Hydrogen-your body is mostly H2O Nitrogen amino acids Oxygen-energy out of food Phosphorous-DNA Sulfur-Protein Selenium micro amounts/ a deficiencyis thought to cause cancer 28. Nonmetals Nonmetals are theopposite. They are dull,brittle,nonconductors(insulators). Some are solid, butmany are gases, andBromine is a liquid. 29. Transition Metals weird number of electrons Cu-copper Au-Gold Ag-Silver 30. Titanium Strong and light it is often used to make frames for bicycles and eyeglasses. 31. Poor metals Al- Aluminum Ga- Gallium In Indium Sn-Tin Ti- thallium Pb- lead Bi- Bismuth 32. inner transition metals Actinide series Lanthanide series used extensively as phosphors, substances that emit light when struck by electrons 33. Metals Malleable & ductile, meaning they can be pounded into thin sheets & drawn into wire Metals met the nonmetals, forming a stair step onthe right hand side of the periodic table. 34. Metals Metals are lustrous (shiny), malleable, ductile, and are good conductors of heat and electricity. They are mostly solids at room temp. What is one exception? 35. The disappearing Spoon Disappearing Spoon Gallium Low melting point Highly radioactive= good bye hand 36. Metalloids B-Boron Si-Silicon Ge-Germanium As-Arsenic Sb-Antimony Te-Tellurium Po-Polonium At-Astatine 37. Metalloids Metalloids, aka semi- metals are just that. They have characteristics of both metals and nonmetals. They are shiny but brittle. And they are semiconductors. What is our most important semiconductor? 38. Metalloids Semiconductors Properties of bothmetals andnonmetals. 39. Metalloids Two importantmetalloids Ge-germanium Si-Silicon Used in computerschips and solar cells 40. Metals, Nonmetals, Metalloids There is a zig-zag orstaircase line thatdivides the table. Metals are on theleft of the line, inblue. Nonmetals are onthe right of the line,in orange. 41. Metals, Nonmetals, Metalloids Elements that borderthe stair case, shownin purple are themetalloids or semi-metals. There is oneimportant exception. Aluminum is moremetallic than not. 42. The Periodic Table & PeriodicLawClassification of Elements 43. Objective: Explain why elements in the same group have similar properties Identify the four block of the periodic table based in their electron configuration 44. Valence Electrons Do you remember how to tell the number ofvalence electrons for elements in the s- and p-blocks? How many valence electrons will the atoms inthe d-block (transition metals) and the f-block(inner transition metals) have? Most have 2 valence e-, some only have 1. 45. Valance electrons 46. Electron configuration 47. s, p, d, and f blocks 48. The Periodic Table & PeriodicLawPeriodic Trends 49. Atomic RadiusDefinition: Half of the distancebetween nuclei in covalentlybonded diatomic molecule Radius decreases across a period Increased effective nuclear chargedue to decreased shielding Radius increases down a group Each row on the periodic tableadds a shell or energy level to theatom 50. Table ofAtomicRadii 51. Explanation Video-Atomic Radii 52. Period Trend:Atomic Radius 53. Ionization EnergyDefinition: the energy required to removean electron from an atom Tends to increase across a period As radius decreases across a period, the electron you are removing is closer to the nucleus and harder to remove Tends to decrease down a group Outer electrons are farther from the nucleus and easier to remove 54. Periodic Trend:Ionization Energy 55. Electronegativity Definition: A measure of the ability of an atom in a chemical compound to attract electronso Electronegativity tends to increaseacross a period o As radius decreases, electrons get closer to the bonding atoms nucleuso Electronegativity tends to decrease downa group or remain the same o As radius increases, electrons are farther from the bonding atoms nucleus 56. Periodic Table of Electronegativities 57. Periodic Trend:Electronegativity 58. Summary ofPeriodic Trends 59. Ionic Radii Positively charged ions formed whenan atom of a metal loses one orCations more electrons Smaller than the correspondingatom Negatively charged ions formedwhen nonmetallic atoms gain one Anions or more electrons Larger than the correspondingatom 60. The Octet Rule The goal of most atoms (except H, Li andBe) is to have an octet or group of 8 electronsin their valence energy level. They may accomplish this by either givingelectrons away or taking them. Metals generally give electrons, nonmetalstake them from other atoms. Atoms that have gained or lost electrons arecalled ions. 61. Ions When an atom gains an electron, it becomesnegatively charged (more electrons than protons) and is called an anion. In the same way that nonmetal atoms can gainelectrons, metal atoms can lose electrons. They become positively charged cations. 62. Ions Here is a simple way to remember which is thecation and which the anion:++This is Ann Ion. This is a cat-ion. Shes unhappy Hes a plussy cat! and negative. 63. Ionic Radius Cations are always smaller than the originalatom. The entire outer PEL is removed duringionization. Conversely, anions are always larger than theoriginal atom. Electrons are added to the outer PEL. 64. Cation FormationNa atom Effective nuclear charge onremaining electrons1 valence electronincreases.11p+ Remaining e- are pulled in closer to the nucleus. Ionic size decreases.Valence e-lost in ionformation Result: a smaller sodium cation, Na+ 65. A chloride ion isAnion Formationproduced. It is larger than the originalChlorine atomatom.with 7 valencee- 17p +One e- is added tothe outer shell. Effective nuclear charge is reduced and the e- cloud expands. 66. Graphic courtesy Wikimedia Commons user Popnose