Development of period table Flashcards
Elements arranged mendeleev vs modern
M- atomic mass but some swapped around
Mo-atomic number
Why did mendeleev leave gaps
Left gaps for undiscovered elements
How were elements grouped
Mendeleev vs modern
M- chemical properties
Mo- number of electrons on outer shell
Metals and non metals placed
Mendeleev vs modern
M-no clear distinction
Mo-metals to left and non metals to the left
What were faults in mendeleevs periodic table
Incomplete and some elements swapped to fit into appropriate groups with no explanation to back it
Discovery of protons
Allowed scientist to order elements by their atomic number
Discovery of neutrons
Led scientist to discovering isotopes which explained why some elements didn’t seem to fit when the periodic table was organised by atomic mass (iodine)
What are noble gases properties
They have full outer shell so done need to lose or gain electrons
Very unreactive (inert) so exposes as single atoms as don’t bond to form molecules
Boiling points increase down the group
What does group one react with
Oxygen , chlorine and water and when reacting with water form alkalis
Group one structure
All have one electron on their outside shells. They are very reactive because of this as they only need to lose one electron to react
Why does reactivity decrease as you go down the group
The atoms increase in size
The outer electron is further away from the nucleus and more shells shielding outer electron from the nucleus
The electrostatic attraction between the nucleus and the outer electron is weaker
So easier to lose the one outer electron
Melting and boiling decrease as you go down group one
What state is fluorine and chlorine in at room temp
Gas
What state is bromine in at room temperature
Liquid
What state is iodine at room temperature
Solid -the melting and boiling points increase as you go down the group
How does reactivity work in group 7
It decreases
