The History of the Periodic Table Flashcards
What was Newland’s Law of Octaves?
Newland had the first atempt on the Periodic Table. He noticed a pattern - this was that every eighth element had the same properties.
What were the issues with Newland’s Law of Octaves?
Some of his octaves consisted of elements that did not have similar properties. He also had mixed up non-metals and metals.
What were Dmitri Mendeleev’s changes?
- Mendeleev came closest to our Modern Periodic Table.
- He ordered the elements in terms of their properties putting similar elements in the same column. He ordered the table in terms of atomic mass.
Why did Mendeleev leave gaps in his version of the Periodic Table?
- Where there was not an element to match with the pattern of properties, Mendeleev left the space gaps suggesting more elements would be discovered.
- The gaps also meant that Mendeleev could predict the properties of the undiscovered elements.
The Modern Periodic Table
- In the late 19th century scientists discovered neutrons, protons and electrons.
- So the Periodic Table is now ordered by atomic number rather than atomic mass.
How is the Periodic Table sorted?
- Columns are called groups and rows are called periods.
- Elements with the same properties have the same number of electrons in their outer shell.
- Elements in the same period have the same number of electron shells.
Periodic Table in 1800s?
Scientists had no understanding of protons, electrons or the atomic structure. They only knew how to calculate relative atomic mass. So the elements were originally arranged in order of atomic mass
How can you predict reactivity?
Atoms react depending on the number of electrons in their outer shell.
So elements in the same group are likely to react in the same way.
This means if you know the properties in one element, you can predict the properties of the other elements in that group.
