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94
How many elements are naturally occurring?
Metals and non metals
What was the result of the earliest attempt of classification?
Groups having three elements each
What are triads?
Calcium
Till where is the Newlands law of octaves applicable
Assume that only 56 elements existed in nature and no more elements would be discovered.
Name a limitation of the Newlands law of octaves
Omitry Ivanvich Mendeleev
Who does the main credit for classifying elements go to?
63 elements
When Mendeleev started his work how many elements were known?
Oxygen and hydrogen
Which elements did Mendeleev select?
Vertical columns
What are groups?
Gallium
Which element was known as ek a-aluminium before
Hydrogen
Give a limitation of Mendeleev's classification.
The relationship between atomic weight of an element and its chemical property
What 's the achievement of dobereiner' s law of triad?
Lithium, sodium, potassium
What is the similarity in their property?
Berrilium, magnesium, calcium and stromium
Name 4 alkaline earth metals
7
What is the total number of periods in the periodic table?
Every 8 element repeats its property
According to which periodic table every 8 element repeats its property
18
How many groups are there in the modern periodic table?
Systematic study of the known element based on certain similarity
State the main aim of classifying elements
Boron, silicon, germanium, arsenic
Name any four metalloids