Modern periodic table
- Created by: Georgia
- Created on: 18-04-13 17:51
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- The modern Periodic Table
- not all scientists thought periodic table was important
- when the periodic table first came out, scientists thought it was just a bit of fun
- wasn't much evidence to suggest elements did fit together like that
- after Mendeleev released work, newly discovered elements fitted in gaps
- this was convincing evidence in favour of the table
- once there was more evidence scientists realised periodic table was useful
- useful for predicting properties of elements
- in late 19th century, scientists discovered protons, neutrons and electrons
- table matched up well with what had been discovered about the atom
- scientists now accept it's importance and useful summary of structure of atoms.
- table matched up well with what had been discovered about the atom
- when the periodic table first came out, scientists thought it was just a bit of fun
- modern periodic table is based on electronic structure
- elements in periodic table can be seen as being arranged by their electronic structure
- using electron arrangement,can predict chemical properties
- electron in atoms are set out in shells which each correspond to an energy level
- apart from transition metals, elements in same group have the same number of electrons in their outer shell
- positive charge of nucleus attracts electrons and holds them in place
- the further from the nucleus the electron is, the less the attraction
- the attraction of the nucleus is even less when there are a lot of inner electrons
- inner electrons 'get in the way' of the nucleus charge, reducing attraction
- this is known as shielding
- inner electrons 'get in the way' of the nucleus charge, reducing attraction
- the combination of increased distance and increased shielding means that an electron in a higher energy level is more easily lost
- as there's less attraction from nucleus holding it in place
- this is why group 1 metals get more reactive as you go down group
- as there's less attraction from nucleus holding it in place
- increased distance and shielding means higher energy level is less likely to gain an electron
- that's why group 7 elements are less reactive as you go down group
- elements in periodic table can be seen as being arranged by their electronic structure
- not all scientists thought periodic table was important
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