Alkali Metals: Group Trend in Properties

As you go down the group:

• their melting points decrease
• their densities increase
• the number of electron shells increases, and by using the density formula, mass/volume, you 'll realise that by increasing the number of electron shells, you are increasing the number of electrons, protons and neutrons as well, which obviously have masses, and thus it will increase the density as it will definitely surpass the increase in volume.
• they become softer
• they become more reactive

"The alkali metals - trends in reactivity."BBC GCSE Bitesize. N.p., n.d. Web. 2 May 2013. <http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/patterns/groupsrev2.shtml>

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