The Modern Peridoic Table Unit 3

The Modern Periodic Table;

• Not ALL scientists thought the periodic table was important.
• At the time of the release of the periodic table there was not a lot of evidence that supported that the elements did fit togther in the way that Mendeleev had constructed. Many scientists thought it was just a bit of fun.
• After is was released new elements were discovered that fitted into the gaps he had left.
• Mendeleevs periodic table also matched up when protons, neutrons and electrons were discovered.
• Scientist now accepted that the periodic table is very important and useful SUMMARY OF THE STRUCTURE OF ATOMS.

Electronic Structures;

• The elements in the periodic table are arranged by electronic structure. This can help predict the elements chemical properties.
• Each atom in the element contains electrons. These electron are organised into electromagnetic shells and show the energy levels of the atom within the element.
• Apart from the transition metals, each element in the same group has the same number of electrons on their outer most shell. The group number indicated the number of electrons in that oouter shell.

Chrages within an Electron

• The posistive charge of the nucleus attracts the electron, because they are negatively charged.
• This means that the further away from the nucleus the outer most shell is the less of the attraction is has to the nucleus.
• The attraction between the nucleus and the outer most shell is also decreased by the number of elctrons between the nucleus and the outer shell. The more electrons between the nucleus and the outer shell the less the force of attraction is. This is called SHEILDING.
• The increased distance and the increased sheilding means that an electron in a higher energy level is more easily lost because the force of attraction is lower.
• Increased distance and sheilding also means that the higher enrgy electrons (ones in the further shell) are more likley to gain an electron because there is less attraction from the nucleus of the atom.