atomic struc and periodic table

JJ thompson

plum pudding model : ball of positive charge with negative electrons embedded in it

Rutherford

gold foil experiment : file alpha particles at a thin gold foil. most went thru bcz most are empty space. some deflected bcz of the nucleus. Some reflected bcz of the concentration of mass in the tiny nucleus

bohr

nuclear model : electrons orbit the nucleus at a specific distance.

chadwick

provided evidence for neutrons in the nucleus

filtration

seperate insoluble solids from a liquid

crystallisation

seperate soluble solids from a solvent

simple distillation

seperate the solvent from the solution

fractional distillation

seperate liquids with their different boiling points

chromatography

seperate substances based on their solubility

mendeleev

arranged the elements by their atomic mass no. switched orders if properties didn’t match. Left gaps for undiscovered elements

todays periodic table

arranged by atomic no.

group 0

noble gases.

unreactive bcz they have a full outer shell and are stable.

boiling point increases as u go down

group 1

alkali metals.

reactivity increases as u go down bcz atoms get bigger so the outer shell is further away from nucleus decreasing the intermolecular forces, so electron is lost more easily.

react with water to form hydrogen and alkali solution.

react with oxygen to form an oxide.

group 7

halogens.

reactivity decreases as u go down bcz atoms get bigger and outer shell further away from nucleus, so electron is harder to gain bcz there’s less attraction.

react w metals to form an ionic compound.

react w non metals to form covalent bonds

reactivity in halogens

more reactive halogen will replace a less reactive halogen in an aq solution of its salt

relative atomic mass (Ar)

(mass of iso 1 x abundance of iso 1) + (mass of iso 2 x abundance of iso 2)

divided by 100

lithium with oxygen

burns with red flame.

forms lithium oxide.

lithium with water