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The Periodic Table. A brief introduction. The 1 st periodic table…. Devised by Dmitri Mendeleev Published in 1869 Compiled on the basis of arranging the 65 elements Arranged in ascending order of atomic weight Grouped them by similarity of properties. The 1 st periodic table….
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The Periodic Table A brief introduction
The 1st periodic table… Devised by Dmitri Mendeleev Published in 1869 Compiled on the basis of arranging the 65 elements Arranged in ascending order of atomic weight Grouped them by similarity of properties.
The 1st periodic table… Was arranged in such a way that : 1) A higher atomic weight than the one on its left. 2) Similar chemical properties to other elements in the same column.
The Periodic Table… Ubiquitous within the academic discipline of chemistry Provides a useful framework to classify, systematize, and compare all of the many different forms of chemical behaviour Contains 118 elements to date.
Classifications… There are nine classifications on the Periodic Table. They are: 1) Metalloids 2) Alkali Metals 3) Alkaline Earth Metals 4) Transition Metals 5) Other Metals 6) Non-metals 7) Halogens 8) Noble Gases 9) Rare Earth Elements
Metalloids Have properties of both metals and non-metals: Solids, shiny or dull, ductile, malleable Conduct heat and electricity better than non-metals but not as well as metals. Chemical reactions are typical of both metals and non-metals.
Alkali Metals Homologous Highly reactive due to only one electron in their outer shell Malleable, ductile, good conductors of heat and electricity Soft, tarnish easily, low melting points and densities Can explode if they are exposed to water
Alkaline Earth Metals Homologous Highly reactive due to two electrons in their outer shell, though not as alkali metals Silvery colored, soft, low-density
Transition Metals Located in Groups 3 to 12 of the periodic table Ductile, malleable, and conduct electricity and heat Very hard, with high melting points and boiling points May have multiple stable oxidation states which allow them to form many different ionic compounds
Other Metals More electronegative than the transition metals Melting and boiling points are generally lower than those of the transition metals Softer Distinguished from the metalloids by their significantly-greater boiling points in the same row
Non-metals Insulators or semiconductors and poor conductors of heat Usually not reactive Can be either solid, liquid or gas Solid forms are more commonly brittle and not ductile like metals Usually have lower densities and melting points than metals
Halogens Require one more electron to fill their outer electron shells Highly reactive Can be harmful or lethal to biological organisms in sufficient quantities Fluorine is the most reactive element in existence, even attacking glass, and forming compounds with the heavier noble gases Halogen reactions produce salts known as halides
Noble Gases Most stable due to having the maximum number of valence electrons their outer shell can hold Rarely react with other elements Conduct electricity, odourless, colourless Used in many conditions when a stable element is needed to maintain a safe and constant environment.
Rare Earth Elements Most of the actinides are trans-uraniums. Never occur free in nature. Are similar because their atomic structures are similar All form compounds with the most common oxidation state 3. Are metals, with high lustre and electrical conductivity. In colour, they are typically silver, silvery-white or grey. At elevated temperatures many ignite and burn vigorously. Are used in petroleum and electronics industries, manufacture of super conductors, permanent magnets, ceramics, glass, and metal alloys.
Bibliography http://www.chemistry.co.nz/mendeleev.htm http://www.chemicool.com/ http://en.wikipedia.org/wiki/Periodic_table http://www.periodic-table.org.uk/ http://www.chemistry.patent-invent.com/chemistry/ www.mpcfaculty.net/mark_bishop/Common_Elements.htm
Thank you ! Hope you have a bit of insight on the Periodic Table !