Chapter 1 – The Periodic Table



8763001181101Element is a substance that cannot be broken down into a simpler substance (is only made up of one type of atom)00Element is a substance that cannot be broken down into a simpler substance (is only made up of one type of atom)Section A: History of the ElementsAncient Greeks – There are only four elements: Earth , water, fire and airRobert Boyle – An element is a substance that cannot be broken down into a simpler substance by chemical meansHumprey Davy – Discovered elements by passing electricity through a molten solution of their compoundsSection B: History of the Periodic TableDobereiner Triads: a group of 3 elements which had similar physical & chemical properties with the atomic weight of the middle element being halfway between the other two.Example of a triad: lithium, sodium and potassiumNewlands Law of octaves : When all of the known elements where listed in order of atomic weight ( mass) every 8th element had similar chemical and physical properties.MendeleevWhen all elements listed in order of increasing atomic weight (mass) the properties repeated themselves at regular intervalsArranged elements in a table called the Periodic TableLeft gaps for undiscovered elementsUsed it to predict properties of undiscovered elementsReversed the order of some elements so that the elements would fit into groups with other elements that shared similar chemical and physical propertiesDifferences between Mendeleev’s Table and the Modern Periodic tableMendeleev’s tableModern Periodic tableHad gaps for elements that were not discovered at the timeHas no gapsElements were placed in order of atomic weightElements placed in order of atomic numberThere were no noble gases includedThere are noble gases includedMoseley – 8382006477000Atomic number the number of protons that an atom of an element has in its nucleus00Atomic number the number of protons that an atom of an element has in its nucleusArranged the elements according to their atomic number. Section C: Case study of a group in the Periodic tableGroup 1 (Alkali metals)All have one electron in their outer shell which they lose readily so they are all very reactive.Properties: Shiny , easy to cut with a knife, reactive with air and water, can float on waterBalanced equations showing reactions with waterThe reactivity increases as you go down the group Why?The outermost electron is further away from the nucleus ( the atomic radii increase) which makes it easier to remove Although the nuclear charge increases as you go down a group the number of shells also increase, this screening effect of the extra shells effectively cancel out the increasing nuclear chargeSelf assessment of your learning of THE PERIODIC TABLEGreen = I have learnt thisOrange = I am not sure – have to revise thisRed = I don’t know this yet – have to learnCan you..GreenOrangeRedDefine an Element?Write the symbols of elements 1–36.Tell briefly the contribution of the Greeks to the History of the idea of elements,Tell briefly the contribution of the Boyle to the History of the idea of elements,Tell briefly the contribution of the Davy to the History of the idea of elements,HL Only:Explain Dobereiner’s contribution to the development of the Periodic tableHL Only:Explain Newland’s contribution to the development of the Periodic tableExplain Mendeleev’s contribution to the development of the Periodic tableGive three differences between Mendeleev's table with the modern periodic table.HL Only:Explain Moseley’s contribution to the development of the Periodic tableDefine atomic numberGive a brief statement of the main similarities of elements within each main group, in particular :alkali metals, alkaline earth metalshalogensnoble gasesExplanations in terms of atomic radius, screening effect and nuclear charge for general trends in properties of elementsin group I. ................
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