Chemical Periodicity

James Lamming
Mind Map by James Lamming, updated more than 1 year ago
James Lamming
Created by James Lamming almost 7 years ago


GCSE Chemistry Mind Map on Chemical Periodicity, created by James Lamming on 05/12/2013.

Resource summary

Chemical Periodicity
1 Periodicity is the repeating pattern of properties in elements.
1.1 This regularity allows elements to be placed in groups
1.1.1 Each element has similar, though gradually varying, properties These properties are both chemical and physical
2 Electron structure
2.1 Electrons orbit the nucleus at certain fixed distances- SHELLS
2.1.1 Each shell can hold up a certain number of electrons Shell 1- 2 Electrons Shell 4- 2 Electrons Shell 3- 8 Electrons Shell 2- 8 Electrons Electrons fill up the nearest shells first Number of electrons in the outer shell= group number
2.2 All chemical reactions are the result of changes in the outer shell of electrons
2.2.1 All elements in a group have the same number of electrons in the outer shell Therefore elements in any group have similar characteristics However, as groups descends, more shells are added More shells means more distance from the positively charged nucleus Therefore it is harder to gain electrons but easier to lose them
3.1 Highly unreactive
3.1.1 Do not form compounds Full outer shell of electrons
3.2 Colourless gases
3.3 Down the group they become
3.3.1 Denser
3.3.2 Gain a higher boiling point
3.4 USES
3.4.1 Helium Airships Party balloons
3.4.2 Neon Filling gas discharge tubes for neon signs Cryogenic refrigeration
3.4.3 Argon Inside lightbulbs to stop filament oxidation Food packaging to stop rotting
3.4.4 Krypton Lasers Killing Superman
3.4.5 Xenon Flash camera bulbs Strobe lights
4.1 Relatively low density
4.1.1 Potassium, Sodium and Lithium float on water
4.2 Shiny when first cut
4.2.1 Tarnish rapidly upon oxidation
4.3 Soft- can be cut by a knife
4.4 Low melting points
4.5 Silvery metals
4.5.1 Caesium is pale-gold colour
4.6 Very reactive- most reactive metal group
4.6.1 Stored under oil or under Argon atmosphere
4.6.2 They react with water to give Oxides
4.6.3 They react with water to give Hydroxides AND Hydrogen These reactions are very vigorous Lithium fizzes around on the surface of the water and seems to dissolve Sodium fizzes around in a molten ball, appearing to dissolve This is because Sodium has a lower boiling point than Lithium AND the reaction is more exothermic Potassium fizzes around in a molten ball, igniting the Hydrogen from the reaction and producing a purple flame The presence of Hydroxide products can be shown using an indicator Hydroxides are alkaline, thus why the metals are also known as the 'alkali metals'
4.7 As the group descends...
4.7.1 The metals become more reactive Become softer Increase in density
4.7.2 The metals want to lose an electron to have a full outer shell The further they are from the protons, the easier they can lose the electron The more shells they have, the further they are from the protons. As they descend the group, the become MORE reactive
5.1 Halogens are reactive non-metals
5.1.1 They are diatomic molecules They have poisonous vapours
5.2 Halogens and their properties
5.2.1 Fluorine Pale yellow Highly toxic Very reactive GAS
5.2.2 Chlorine, Cl2 Pale green gas Dense Toxic GAS
5.2.3 Bromine, Br2 Dense Dark red LIQUID Gives off red/brown vapour Toxic and Corrosive
5.2.4 Iodine Dark grey SOLID Sublimes to give a purple vapour Forms a brown solution in water and a purple one in Hexane
5.2.5 Astatine is radioactive and very unstable
5.2.6 They are ALL poor conductors of heat and electricity
5.3 On descending the group...
5.3.1 They become less reactive They are trying to ATTRACT electrons, unlike the Alkali metals This means they want to be nearer the protons and the nucleus Therefore they want fewer shells between them and the nucleus
5.3.2 Their colour becomes darker
5.3.3 Their melting and boiling points INCREASE
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