Advertisements
Advertisements
प्रश्न
Helium atom has 2 electrons in its valence shell but its valency is not 2, Explain
Advertisements
उत्तर
Helium has only one shell (K – shell) and the maximum number of electrons within K shell can be 2. Hence the valency is zero.
APPEARS IN
संबंधित प्रश्न
If the number of electrons in an ion Z3– is 10, the atomic number of element Z will be :
The atomic number of an element E is 16. The number of electrons in its ion E2– will be :
The atom of an element X contains 17 protons, 17 electrons and 18 neutrons whereas the atom of an element Y contains 11 protons, 11 electrons and 12 neutrons.
- What type of ion will be formed by an atom of element X ? Write the symbol of ion formed.
- What will be the number of (i) protons (ii) electrons, and (iii) neutrons, in the ion formed from X ?
- What type of ion will be formed by an atom of element Y ? Write the symbol of ion formed.
- What will be the number of (i) protons (ii) electrons, and (iii) neutrons, in the ion formed from Y ?
- What is the atomic mass of (i) X, and (ii) Y ?
- What could the elements X and Y be ?
What name is given to this number ?
What is the number of molecules in 1.5 moles of ammonia ?
Calculate the number of molecules in 4 g of oxygen.
If 32 g of sulphur has x atoms, then the number of atoms in 32 g of oxygen will be :
What mass of nitrogen, N2, will contain the same number of molecules as 1.8 g of water, H2O ?
(Atomic masses : N = 14 u ; H = 1 u ; O = 16 u)
The mass of one atom of an element X is 2.0 × 10–23 g.
Calculate the atomic mass of element X.
What could element X be ?
Classify each of the following on the basis of their atomicity.
- F2
- NO2
- N2O
- C2H6
- P4
- H2O2
- P4O10
- O3
- HCl
- CH4
- He
- Ag
Which has more number of atoms?
100g of N2 or 100 g of NH3
Compute the difference in masses of one mole each of aluminium atoms and one mole of its ions. (Mass of an electron is 9.1×10–28 g). Which one is heavier?
A silver ornament of mass ‘m’ gram is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.
In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting requisite number of electrons, then what would be the charge on the ion so formed?
Match the names of the Scientists given in column A with their contributions towards the understanding of the atomic structure as given in column B
| (A) | (B) | ||
| (a) | Ernest Rutherford | (i) | Indivisibility of atoms |
| (b) | J.J.Thomson | (ii) | Stationary orbits |
| (c) | Dalton | (iii) | Concept of nucleus |
| (d) | Neils Bohr | (iv) | Discovery of electrons |
| (e) | James Chadwick | (v) | Atomic number |
| (f) | E. Goldstein | (vi) | Neutron |
| (g) | Mosley | (vii) | Canal rays |
An element X has a mass number 4 and atomic number 2. Write the valency of this element?
