Module 3 Section 1 - The Periodic Table Flashcards
How were elements categorised in the early 1800s?
1) physical and chemical properties
2) relative atomic mass
They did not know about protons or electrons yet so the only thing they could measure was relative atomic mass.
History of the periodic table before Mendeleev?
1) in 1817, Johann Döbereiner attempted to group similar elements. These groups were called dobereiner’s triads. He saw that chlorine, bromine and iodine had similar characteristics. He also found that bromine’s atomic weight was halfway between chlorine and iodine.
2) John newlands made the first periodic table in 1863. He noticed if he arranged the elements in order of mass, similar elements appeared at regular intervals- every eight was similar. He called this the law of octaves.
When did Mendeleev produce his periodic table?
1869
How did Mendeleev arrange his periodic table?
He arranged all the known elements by atomic mass, but left gaps in the table where the next element did not seem to fit. This was elements with the same chemical properties were in the same group.
He also predicted properties of undiscovered elements that would go in the gaps.
Who created the modern periodic table?
Henry Moseley
When was the modern periodic table created?
1914
How are elements arranged in the modern periodic table?
They are arranged in increasing atomic number rather than mass.
What is the Structure of the periodic table ?
1) It is arranged into periods (rows) and groups (columns)
2) all the elements within a period have the same number of electron shells.
3) all the elements within a group have the same number of electrons in their outer shell.
What is periodicity?
The repeating trends in the physical and chemical properties of the elements in a group or period.
What are the blocks in the periodic table?
S block, d-block, p-block and f-block
What are s block elements?
Group 1 and 2. They have s1 and s2 in their outer shell electron configuration.
What are d block elements?
The transition elements . These elements have electron configurations in which d sub shells are being filled.
What are p block elements
Groups 3-8. They have an outer shell configuration of s2p1 to s2p6.
