How were element catergorized back then?
- By their physical and chemial properties
- By their relative atomic mass
In the past, what were they not aware of in terms of elements?
Atomic structures (there was no atomic number as they didnt know about protons or electrons)
Back then how were the elements arranged in order of?
Relative atomic mass
How did Newlands arrange the elements?
He notices that every eigth element had similar properties and listed them in rows of seven
Why was Newlands work ignored?
Because he left no gaps
Why was Newlands work criticised? (3
- His groups contained elements that didn't have similar properties eg carbon and titanium
- He mixed up metals and non-metals
- He didn't leave any gaps
How did Mendeleev put the elements into order?
In order of atomic mass (like Newlands) but he found he had to leave gaps in order to keep elements with similar properties in the same vertical columns
At first why did many scientist not think it was that important?
- At the time there wasn't much evidence to suggest that the elements did fit together in that way (things aren't approved without evidence)
What happened that was in favour of the table?
Newly discovered elements fitted into the gaps he had left
→ Also when protons, neutrons and electrons were discovered they fit in very well with the table
When protons, neutrons and electrons were discovered, how was the periodic table arranged?
In order of atomic number
Modern Periodic Table: How are elements arranged?
In order to electronic structure
How can you predict the properties of an element?
Using the electron arangement
Modern Periodic Table: What do elements in the same group have the same of?
EXCEPT TRANSITION METALS
They have the same number of electrons in their outer shell
Modern Periodic Table: What is the group number equal to?
The number of electrons in each elements outer shell
What is shielding?
When inner electrons get in the way of nuclear charge, thus reducing the attraction