L3 - The Periodic Table of Elements Flashcards
When was Dobereiner’s Law of Triads formed?
1817
Describe Dobereiner’s Law of Triads.
Organised elements in groups of three based on physical and chemical properties - found that the atomic masses of the 3 elements formed a pattern.
When was Newlands’ Law of Octaves formed?
1864
Describe Newlands’ Law of Octaves.
Organised elements in increasing order of atomic mass, and noticed that every 8th element exhibited similar properties.
When was Mendeleev’s Periodic Table formed?
1869
Describe Mendeleev’s Periodic Table.
- Arranged elements known at that time in order of relative atomic mass
- Realised that physical and chemical properties of elements were related to their atomic mass in a ‘periodic’ way, and arranged them so that groups of elements with similar properties were in vertical columns in his table
- Left gaps in horizontal rows; assumed it meant that these elements had not yet been discovered
When was Seaborg’s Periodic Table formed?
1940
Describe Seaborg’s Periodic Table.
- Expanded beyond Mendeleev’s initial 63 elements
- Vertical columns = groups
- Horizontal rows = rows
How is the Periodic Table arranged?
- Elements are arranged in order of atomic number, from left to right
- Progression runs from metals to non-metals across each period
Which group are the noble gases found in?
Group 8
State the Periodic Law.
“Properties of elements are periodic functions of their atomic numbers.”
What happens when elements are arranged in order of increasing atomic number?
There is a periodic pattern in their physical and chemical properties.
What are ‘families’ of elements?
Elements that share certain characteristics, not only in terms of observable behaviour, but also atomic structure.
State the common classifications of elements on the Periodic Table.
- Alkali Metals
- Alkaline Earth Metals
- Transition Metals
- Lanthanides
- Actinides
- Noble Gases
- Non-Metals
- Metalloids
Describe Group 1: Alkali Metals.
- Silver coloured
- Soft metals
- Highly reactive
- Rarely found in elemental form in nature