SC4b Flashcards
How did Moseley show that atomic number was a physical property?
He fired high-energy electrons at different elements causing them to give off X-rays and for every step increase in atomic number there was a stem change in the X-rays energy
What did Moseley realise atomic number was equal to?
The number of positive charges in the nucleus of an atom (protons)
What is the difference between Mendeleev’s atomic number and Moseley’s modern atomic number?
Mendeleev’s was just a position in the periodic table but Moseley’s was a physical property of the element
How are elements in a row (period) organised?
In order of increasing atomic number
How are columns (groups) organised?
Elements with similar properties
What kind of elements are on the right of the table?
The non-metals (the rest are metals)
Why was iodine and tellurium reversed?
As tellurium has several different isotopes causing its relative atomic mass to be greater that that of iodine
What do all group 6 elements have in common?
They all react with oxygen (except oxygen itself), none of them react with water and they all form compounds containing hydrogen
What do all group 7 elements have in common?
None of them react with oxygen, they all react with water and they all form compounds containing hydrogen
What was the first element with an atomic number above 92 and when was it discovered?
Neptunium in 1940
