1. When Mendeléev started his work, 63 elements were known. 2. He examined the relationship between the atomic masses of the elements and their physical and chemical properties.
1. When Mendeléev started his work, 63 elements were known.
2. He examined the relationship between the atomic masses of the elements and their physical and chemical properties.
Name two elements that have two electrons in their outermost shells.
Be and Ca
Be and Ca
See lessName three elements that have a single electron in their outermost shells.
All first group elements like Li, Na, K, etc.
All first group elements like Li, Na, K, etc.
See lessName two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice?
Be and Ca Same group Same chemical property Two electron in outmost shell.
Be and Ca
- Same group
- Same chemical property
- Two electron in outmost shell.
See lessHow could the Modern Periodic Table remove various anomalies of Mendeléev’s Periodic Table?
Isotopes problem is solved. Noble gases which are discovered later placed separately. Atomic numbers are now increasing in regular way.
- Isotopes problem is solved.
- Noble gases which are discovered later placed separately.
- Atomic numbers are now increasing in regular way.
See lessName the elements that separated the metals and non-metals in periodic table.
Metalloids separates metals and non-metals.
Metalloids separates metals and non-metals.
See lessFill in the blanks: The basis of modern Periodic table is _______________
Properties of elements are periodic function of their atomic number.
Properties of elements are periodic function of their atomic number.
See lessFill in the blanks: Group 17 elements are called ______________
Yes it halogen.
Yes it halogen.
See lessWhy do you think the noble gases are placed in a separate group?
These are least reactive gasses.
These are least reactive gasses.
See lessWhat were the criteria used by Mendeleev in creating his Periodic Table?
1. When Mendeléev started his work, 63 elements were known. 2. He examined the relationship between the atomic masses of the elements and their physical and chemical properties.
1. When Mendeléev started his work, 63 elements were known.
See less2. He examined the relationship between the atomic masses of the elements and their physical and chemical properties.
Besides gallium, which other elements have since been discovered that were left by Mendeleev in his Periodic Table? (any two)
In NCERT Gallium, Scandium and Germanium are given but more elements are there which are discovered later.
In NCERT Gallium, Scandium and Germanium are given but more elements are there which are discovered later.
See less