8303237-69-Trends-in-Physical-Props-Revised - Chem...

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Revision Summary: Trends in the Periodic Table 1 Number 69 1 C hem F actsheet www.curriculum-press.co.uk Before working through this Factsheet you should: Be familiar with the organisation, layout and information available from the Periodic Table; Have studied the AS and A2 work on periodic trends. After working through this Factsheet you will have revised: The layout of the Periodic Table; Trends in physical properties and their explanation. This Factsheet provides a revision summary of periodic table work. If you would like more explanations on any aspect, these can be found in Factsheets 12, 13, 14, 19 and 20. Factsheet 68 also looks at periodic trends in a different context. Questions on trends in the Periodic Table are popular at AS and A2 level. Such questions often require two styles of preparation: Factual recall – statement of a trend and evidence of it, e.g. the recall of particular chemical equations. Application and understanding – answers require a description of why there is a particular trend. First, revision of the Periodic Table itself. The elements are placed in order of increasing atomic number. Period: Horizontal row of elements. Group: Vertical column of elements. You need to learn the following group names: Group Number Group Name 1 Alkali Metals 2 Alkaline Earth Metals 7 Halogens 0 Noble Gases Properties of an element are a periodic function of their atomic numbers. Properties repeat regularly, so that elements in the same group tend to display similar chemical and physical properties . s, p, d and f blocks The Periodic Table is divided up into 4 blocks (s, p, d and f) which show which is the outer electron sub-shell for the elements in that block. s-block elements : - the metals in group 1 and 2, so called because their outer shell contains s electrons. e.g. Sodium (Na): Atomic no. 11. Elec. config. 1s 2 2s 2 2p 6 3s 1 p-block elements : - the elements from groups 3 to 7, as they have outer electrons which are p-electrons. e.g. Carbon (C): Atomic no. 6. Elec. config. 1s 2 2s 2 2p 2 d-block elements : - the metals in the block between groups 2 and 3, known as the transition metals . d-block elements have incomplete d-sub shells. e.g. Titanium (Ti): Atomic no. 22. Elec. config. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2 f-block elements : - a block of elements within the transition metals, so called because electrons are being added into the f-subshell in these elements. e.g. Cerium (Ce) Atomic no. 58. Elec. config. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4s 6 5s 2 4d 10 5p 6 6s 2 4f 2 Metals, Metalloids and Non-metals These can also be shown to be grouped on the Periodic Table: 234 234 23 23 23456 23456 23456 123456 123456 123456 345670 f d s BC NOF N e Al Si PSC lA r Ga Ge As Se Br Kr In Sn Sb Te IX e Tl Pb Bi Po At Rn metals non-metals metalloids To categorise the elements into one of these three types, the following criteria can be used: Metals Good conductors of electricity Form basic oxides (a few form amphoteric oxides) Metalloids Poor conductors of electricity (except graphite) Form amphoteric oxides Non-metals
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This note was uploaded on 03/08/2011 for the course CHEM 101 taught by Professor Hard during the Spring '11 term at UT Arlington.

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8303237-69-Trends-in-Physical-Props-Revised - Chem...

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