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Periodic Table. The First Periodic Tables. Dmitri Mendeleev is known as the father of the periodic table, the work of many scientist contributed to its present form e lements such as Gold (Au), Silver (Ag), Tin ( Sn ) , Copper (Cu) and Mercury (Hg) have been known of for ages
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The First Periodic Tables • Dmitri Mendeleev is known as the father of the periodic table, • the work of many scientist contributed to its present form elements such as Gold (Au), Silver (Ag), Tin (Sn), Copper (Cu) and Mercury (Hg) have been known of for ages • The first discovery of an element occurred in 1649 by Henning Brand with his discovery of Phosphorous (P) • In 1869 a total of 63 elements had been discovered
The First Periodic Tables • A.E. Beguyer de Chancourtois – French Geologist transcribed a list of elements positioned on a cylinder in terms of increasing atomic weight • the cylinder was constructed so that 16 mass units could be written on the cylinder per turn closely related elements were lined up vertically • which led De Chancourtois proposed that the properties of the elements are the properties of numbers • first to recognize that elemental properties reoccur every seven elements ~ allowing him to predict the stoichiometry
Who is the Father of the Periodic Table? • Lothar Meyer (German) • Meyer’s textbook included a rather abbreviated version of a periodic table used to classify elements in order of their atomic weight and demonstrated periodic valence charges as a function of atomic weight • Unfortunately, his periodic table did not appear until 1870
Who is the Father of the Periodic Table? • Dmitri Mendeleev (Russian) • Became a teacher of science, then became a professor of chemistry • While writing a textbook, he organized his materials in terms of families of the known elements which displayed similar properties
More on Mendeleev… • He created a card for each of the 63 known elements • Each card contained the element’s symbol, atomic weight, and its characteristic chemical & physical properties • Advantage was that in previous attempts was that it exhibited similarities in an entire network of vertical, horizontal and diagonal relationships
Mendeleev continued… • His periodic table was a work in progress, the atomic masses were not always accurate • He found that 17 elements had to be moved to new positions by atomic weight for the properties to correlate with other elements • He predicted the existence and properties of unknown elements (Al, B, Si) and other elements found later fit his predictions • Even though his Mendeleev’s table was published before Meyer, his work was more extensive
The Periods • The rows, that go from left to right • All the elements in the same row, or period, have something in common • They have the same number of orbitals (or shells) • The maximum number of shells is seven
The Groups • Also called the families • Alkali Metals, Alkaline Earth Metals, Transition Metals, Halogen Gases, Nobel Gases • Physical Properties: density, boiling point, melting point, conductivity, heat capacity • Chemical Properties: valence, reactivity, radiioactivity
The Groups • The columns go from top to bottom • They have the same number of electrons in their outer most orbital or shell • Those electrons in the outer shell are called valence electrons • They are the electrons involved in chemical bonds with other elements
Hydrogen & Helium • Hydrogen & Helium are special elements • Hydrogen can have the talents and electrons of two groups, 1 & 7 • Hydrogen will give away its one electron but also will only need one electron to makes its outer most shell full, with two
Hydrogen & Helium • Hydrogen & Helium are special elements • Helium is different than all the other elements • It is grouped with the noble gases because it is happy… like the other noble gases because its outer shell is full and happy…
Let’s Get to Know the Metals • Almost 75% of all elements are classified as metals • There are four traits that help you identify whether an element is a metal or not • Conduction ~ conduct electricity • Reactivity ~ they react easily, forming compounds easily • Chemical~ usually make positive ions when the compounds are dissolved in solution • Alloys ~ easily combined
Alkali Metals • The first column on the left side of the periodic table • These elements are very reactive, a desire to bond • They only have one electron in the outer most shell, meaning they will give up their electron to be happy • When you put some of these pure elements in water (H2O) they can cause huge explosions • Shinny and light in weight • They are malleable (bendable)
Alkaline Earth Metals • Second column on the left • Second most reactive • Most likely to form solutions with a pH greater than 7 • They form ionic bonds • Often with halogen atoms and sometimes form double bonds • Towards the bottom of the list you will find radioactive elements, such as radium… the stuff in glow-in-the-dark paints • Also the lighter alkaline earth metals are used in animal and plant physicology
Transitional Metals • Many elements are considered transition metals • What makes them so special? It has to do with their orbitals/shells • They distribute their electrons differently • Able to put up to 32 electrons in their second-to-last shell
Metalloids • Found along the stair-step line (or zig-zag) that distinguishes metals from non-metals • A cross between metals and nonmetals • Some are semi-conductors (carrying electrical charge under special conditions • Useful in computers and calculators • Aluminum is classified under “other metals”
Halogens • The second column from the right • Have seven electrons in the outer shell • All are one shy of having a full shell • Very reactive, but decreases in reactivity as you move down the column • When they combine with another element they are called halides
Noble Gases • Used to be called inert gases, but other elements fall into that classification (N2) • Found on the far right column of the periodic table • The are the happiest of all elements ~ because their outer most shell is “happy, happy, happy!” • Using Bohr Model we see this • They do not need to react with other elements • The non-reactivity is why they are called inert
Lanthanide Series of Metals • Sometimes call them the rare-earth metals • Others call them the inner-transition elements • Can only be found naturally on Earth • These elements are found in superconductors, glass production or lasers
Actinide Series of Metals • ALL radioactive • Some are not found in nature • Those with high atomic numbers have only been made in labs • Plutonium (Pu) is the element that makes up atomic bombs • Americium (Am) is the element found in metal detectors