The Periodic Table. Antoine LaVoisier - the “father of chemistry” By late 1700’s had compiled list of 23 elements Chemical-based industry in 1800s greatly expanded the use and discovery of elements In 1864, John Newlands : “Law of Octaves”
Moseley: Noticed that the periodic table worked better if ordered by Atomic Number (Protons) rather than Atomic Mass
Law: A predictable repetition of chemical and physical properties of the elements is found when arranged by atomic number.
Francium is one of the rarest elements on Earth. It is the radioactive byproduct of the decay of Uranium and Actinium. It only has a half-life of 22 minutes, so it is very hard to analyze. How can we predict its physical properties?
Atomic number of Alkali Metal
Element’s Atomic Radius determined by
Net Effective Nuclear Charge:
Cats are Positive!
Metals usually form cations.
Non-metals usually form anions
X + e− → X−
The first electron affinities of the group 17 elements
What makes atoms form certain ions?