The Periodic Table Flashcards
What are columns (going down) on the periodic table called ?
Groups.
What are the rows (going across) on the periodic table called ?
Periods.
What do elements in the same group have in common ?
Number of electrons on their outer shell, similar chemical properties.
What do elements in the same period have in common ?
Number of shells in their atom.
What is the definition of a metal ?
An element that reacts to form a positive ion.
Are the majority of the elements metals or non-metals ?
Metals.
Where in the periodic table are non-metals found ?
Non-metals are found in the top right of the periodic table.
How did scientists attempt to classify the elements before the discovery of the proton ?
They arranged the elements in order of atomic wheight.
What was the problem with this ?
The early periodic table was incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
How did Mendeleev overcome this problem ?
Mendeleev left gaps for elements he thought had not been discovered yet. He also changed the order of atomic weights in some cases.
What evidence was later found to support mendeleeve’s periodic table ?
Elements with properties predicted by Mendeleev were discovered and filled the gaps. The discovery of isotopes explained why arranging by atomic weight did not always work.
