C2.1: The Periodic Table
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What is the atomic number?
The number of protons and electrons
What is the mass number?
The number pf protons + number of neutrons.
Is the mass number at the top or bottom?
Top
Is the atomic number at the top or bottom?
Bottom
When did Dalton publish his table of elements book?(called a new system of chemical philosophy)
1808
In Daltons table what had he arranged the elements in order of?
Atomic weights, witch had been measured in various chemical reactions.
What was the name of the book published in 1809 by Dalton
A new system of chemical philosophy
In what year did John New,ands build on Dalton’s idea?
1864
What was the name of te table produced by John Newlands showing his _________
Law of octaves
What did John Newlands notice about the elements?
Every 8th seemed similar. He also (like Dalton arranged it in order of mass).
What was wrong with Newlands table?
He did not take into account that scientists were still discovering new elements. He filled his octaves even though some of the elements were not similar at all. It only really worked up till Calcium then his pattern broke down.
When did russian chemist Dmitri Mandeleev crack the problem?
1869
How did Mendeleev crack the problem?
• He put them in order of atomic weights • He arranged them so a regular occurring pattern of properties could be seen. • He left gaps for elements that had not been discovered yet • He used his table to predict what their properties would be. • A few years later, new elements were discovered with properties that closely matched his Mandeleev’s predictions causing the majority to view it as correct and a breakthrough in scientific understanding.
Do all elements fit the pattern?
No
Were noble gasses discovered when mandeleev made the table?
No
What caused this problem
Isotopes accounted for the oddly heavy weight of some elements. It kind of messed up the pattern a little bit
Why was the problem able to be fixed?
When scientists discovered more about the atom (neutrons)