Atomic numbers of elements A, B, C and D are 3, 9, 11 and 17 respectively. Identify two pairs amongst the elements which have similar chemical properties. Which pair is likely to be metallic in character?
Atomic numbers of elements A, B, C and D are 3, 9, 11 and 17 respectively. Identify two pairs amongst the elements which have similar chemical properties. Which pair is likely to be metallic in character?
In order to identify two pairs amongst the elements which have similar chemical properties and identify metallic character, number of electrons present in the outermost shell (valence electrons) should be known.
- The elements which have the same number of valence electrons exhibit similar chemical properties. This is because only valence electrons participate in the chemical reactions and influence chemical properties of any substance.
To find out the valence electrons, electronic configuration should be written first.
- Electronic configuration: The distribution of electrons in the orbits around the nucleus in an atom.
Step-1: Write electronic configuration
Atomic number= Number of protons
Also, Number of protons= Number of electrons for an atom
- Begin to fill electrons from the innermost shell (or K shell) to outermost shell
- The maximum number of electrons that can be accommodated in first, second and third shells are 2, 8, 18 respectively.
- The electrons are filled in shells in a sequential manner.
- The maximum number of electrons in a valence shell can be 8.
Step-2: Find out the valence shell and its electrons
- The outermost shell is the valence shell and the electrons in it are the valence electrons.
Metallic/ Non-metallic character:
- If the number of valence electrons is less than 4, the element is a metal.
- If the number of valence electrons is 4 or more than 4, the element is a non-metal.
Elements Number of electrons Electronic configuration Valence electrons Metallic/ Non-metallic A 3 2, 1 1 Metallic B 9 2, 7 7 Non-metallic C 11 2, 8, 1 1 Metallic D 17 2, 8, 7 7 Non-metallic
Therefore, pair wise results are as follows:
Pair Pair
constituents
Chemical properties Nature of
Pair
1 A and C (1 valence electron) A and C have similar chemical properties Metallic pair 2 B and D (7 valence electrons) B and D have similar chemical properties Non-metallic pair
In order to identify two pairs amongst the elements which have similar chemical properties and identify metallic character, number of electrons present in the outermost shell (valence electrons) should be known.
- The elements which have the same number of valence electrons exhibit similar chemical properties. This is because only valence electrons participate in the chemical reactions and influence chemical properties of any substance.
To find out the valence electrons, electronic configuration should be written first.
- Electronic configuration: The distribution of electrons in the orbits around the nucleus in an atom.
Step-1: Write electronic configuration
Atomic number= Number of protons
Also, Number of protons= Number of electrons for an atom
- Begin to fill electrons from the innermost shell (or K shell) to outermost shell
- The maximum number of electrons that can be accommodated in first, second and third shells are 2, 8, 18 respectively.
- The electrons are filled in shells in a sequential manner.
- The maximum number of electrons in a valence shell can be 8.
Step-2: Find out the valence shell and its electrons
- The outermost shell is the valence shell and the electrons in it are the valence electrons.
Metallic/ Non-metallic character:
- If the number of valence electrons is less than 4, the element is a metal.
- If the number of valence electrons is 4 or more than 4, the element is a non-metal.
| Elements | Number of electrons | Electronic configuration | Valence electrons | Metallic/ Non-metallic |
| A | 3 | 2, 1 | 1 | Metallic |
| B | 9 | 2, 7 | 7 | Non-metallic |
| C | 11 | 2, 8, 1 | 1 | Metallic |
| D | 17 | 2, 8, 7 | 7 | Non-metallic |
Therefore, pair wise results are as follows:
| Pair | Pair constituents | Chemical properties | Nature of Pair |
| 1 | A and C (1 valence electron) | A and C have similar chemical properties | Metallic pair |
| 2 | B and D (7 valence electrons) | B and D have similar chemical properties | Non-metallic pair |
