Atomic Structure and the Periodic table: Development of the Periodic Table (DONE) Flashcards
Why is the periodic table called the periodic table?
The word periodic means occurring at regular intervals and in the periodic table elements with similar properties occur at regular intervals.
Why do all the elements in a group react in a similar way?
All elements in a group react in a similar way because they have the same number of electrons in their outer energy level.
What did the scientist Dobereiner discover?
The scientist Dobereiner noticed that elements with similar chemical properties often occurred in three’s. He called these “triads”
eg. Lithium, sodium, potassium which are all metals that react rapidly with water. Another eg. chlorine, bromine, iodine which are all reactive non-metals.
What did the scientist John Newlands discover?
John Newlands noticed that if you arrange the elements in order of increasing atomic weight. Every eighth element react in a similar way.
This is called the law of octaves.
What is the name of John Newlands discovery?
The name of John Newlands discovery is the law of octaves.
What was a problem with John Newlands law of octaves? (1)
One problem with John Newlands law of octaves is by sticking to the exact order of atomic weight, sometimes elements with completely different properties were grouped together.
How did Dimitri Mendeleev develop the first modern periodic table? (3)
Dimitri Mendeleev developed the first modern periodic table by arranging all the elements in order of increasing atomic weight. Mendeleev if he needed to, he would then switch the order of specific elements so they fitted the patterns of other elements in the same group. He also realised that some elements had not been discovered so he simply left gaps in his periodic table where he thought an element was missing. Several years later the elements Mendeleev predicted were missing were discovered so scientists accepted his table was correct.
What separates the periodic table we have today and Dimitri Mendeleev’s? (2)
Dimitri Mendeleev’s periodic table and the periodic table we have today is a bit different because (1) in the modern periodic table the elements are arranged in order of atomic number. When we order by atomic number every element is in the right group. (2) The modern periodic table has group 0: the noble gases.
Why were a lot of the older versions of the periodic table arranged by atomic weight?
A lot of the older versions of the periodic table were arranged by atomic weight because protons (atomic number) had not yet been discovered.
What is the problem with arranging the periodic table by atomic weight?
The problem with arranging the periodic table by atomic weight is elements can appear in the wrong order due to the presence of isotopes.
Mendeleev addressed this problem by switching the order of elements when he needed to.
When Dimitri Mendeleev created his version of the periodic table had the noble gases: group 0 been discovered?
When Dimitri Mendeleev created his version of the periodic table the noble gases: group 0 had not been fully discovered.
