C2 Periodic Table Flashcards
How were atoms described in the earth 19th Centery
Solid spheres
What did JJ Thomas discover? When?
1897
Plum pudding model. The atom is a positivly charged ball with electrons fixed inside it’s mass
What did Rutherfod discover? When?
1909.
Rutherdford and his student Marsden conducted the alpha particle scattering experiment and discovered that:
There are tiny positivly charged protons at the center of an atom (nucleus) where the mass is concentrated. And a “cloud” of electrons around it.
What was the alpha scaytering experiment?
Rutherfod and his student Marden fired positivly charged alpha particles at an extreamly thin sheet of gold.
They thought most would go through and a couple may deflect slightly at the most.
Once they did the experiment most of the particles went through but some were deflected by a lot and some even deflected back. This ment that the plum pudding model couldn’t be right.
What did Bohr discover?
The Nuclear Model
The atoms are in fixed shells and are orbiting around an atom. This was supported by many experiments and it helped scientists a lot to understand the atom.
Who discovered the proton?
Rutherd and other scientists did experiments that proved that the nucleas could be split into smaller partices with the same charge as an hydrogen atom
They called this a proton
What did James Chadwick discover? When?
1932
There were nutrons in the atom
How many electrons are allowed in the first 3 shells?
2
8
8
What happens to an atom which doesn’t have a complete outer shell?
They try and react with something so that it can complete it’s outer shell. This is becasue having a full outer shell makes the electrons more stable
How was the original periodic table organised?
Atomic weight
Why were early periodic tables not correct?
They ordered them by atomic weight and they didn’t think about there phycical properties.
What made Mendeleev’s periodic table better?
Although he did order the elements in order of atomic weight he switched some around so that there phycical properties would match
He left gaps in the periodic table for elements which hadn’t been discovered pr where no element had similar phycical properties
About how many elements are there?
100ish
How is the morden periodic table organised?
Increasing atomic number (amount of protons)
This means that there are reccuring patterns and properties in the elements
What is a column?
A verticle group of column of elements which have similar properties
