The Periodic Table:
Facts to Note:
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The periodic table is an arrangement of the elements in order of increasing atomic number.
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The periodic table is arranged into vertical columns called groups and horizontal rows called periods.
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Each individual group (vertical column) has a name
Group Names:
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Group 1: Alkaline Earth Metals- Mix with water
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Group 2: Allali metals- Found in the Earth as minerals
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Group 3-6: Transition metals
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Group 7: Halogens- Makes salt
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Group 8: Inert/Noble gases- Very Unreactive
Notes on the Periodic Table:
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All elements in the same group have similiar chemical properties. For example they all have the same number of electrons in their outer orbit
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Elements in the same group tend to react vigoursly with the same sunstances. For example sodium reacts with water, therefore it is presumed potassium does likewise as it is in the same group
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In fact all elements in group 1 react with water to form a soluble base (alakli). For example sodium and water react to give sodium hydroxide (a soluble base)
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The periodic table is seperated into metals and non-metals by a set of "stairs". On the right there are non- metals and on the left there are metals
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These metals have certain properties. For example they are lustrous (shiny), ductile (can be stretched) and malleable (beaten into various shapes)
Electron Configurations:
Sodium reacting with water
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The arrangement of electrons in the electron cloud is known as electron configuration
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The periods or horizontal rows on a periodic table can help us with electron configuration. For example if there an element is in the second period (it would be labelled as n=2) it would mean the elements in that row have 2 outer shells
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If an element is in group 2 it means it has 2 electrons in its outer orbit
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Electrons are arranged into three shells. The first has 2, the second has 8 and the third also has 8.
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You may be asked to draw an electron configuration for an element in an exam. Here are the steps you must take:
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Find out how many electrons the atom of the element has
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Draw the necessary amount of orbits
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Place the electrons in the correct order-2,8,8
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Label each orbit n=1, n=2, n=3 depending on how many shells there are
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In the centre of the electron configuration place the nuclear formula i.e atomic number, mass number and element name.
An electron configuration of potassium
Isotopes:
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Isotopes are atoms of the same element that have different mass numbers due to the difference in the number of electrons
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For example carbon has three isotopes-Carbon 12, 13 and 14
