AQA GCSE combined science (trilogy) chemistry

  • Created by: Bobbycar
  • Created on: 02-10-19 13:21

history of the periodic table

In the 1800s, atoms were arranged in atomic mass, as protons, neutrons and electrons had not been discovered.

but, some elements had not been discovered.

Newlands used the Law of octaves. elements were in groups of eight, so some non metals ended up with metals.

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the modern periodic table

elements are in atomic number

there are over 100 elements

groups have the same number of outer electrons

periods represent shells, eg period 1 has 1 shell

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group 1- alkali metals

the elements are: Li, Na, K, Rb, Cs, Fr

these are VERY reactive, with Francium being radiated.

as you go down: 

reactivity increases

melting and boiling point get lower

atomic mass goes up

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group 7- halogens

the elements: F, Cl, Br, I, At

as you go down:

they become less reactive,

they have higher melting and boiling points

higher atomic masses

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