Suppose a gaseous mixture of He,Ne,Ar and Kr is irradiated with photons of the frequency appropriate to ionize Ar,What ion(s) will be present in the mixture?
- Ar+
- Kr+
- He+
- Both A and B
The Correct Option is B
Solution and Explanation
The correct answer is option (B): Kr+
Explanation:
When a gaseous mixture of He, Ne, Ar, and Kr is irradiated with photons that have just enough energy to ionize argon (Ar), the following points are important:
- Ionization energy is the energy required to remove an electron from an atom.
- If a photon has energy equal to the ionization energy of Ar, then it has enough energy to ionize atoms with lower ionization energy than Ar, but not those with higher ionization energy.
Ionization energies (approximate values):
- He: 24.6 eV
- Ne: 21.6 eV
- Ar: 15.8 eV
- Kr: 14.0 eV
Since the photon energy is just enough to ionize Ar (15.8 eV), it cannot ionize He or Ne (which require more energy), but it can ionize Kr (which requires less).
Hence, only Kr will be ionized, forming Kr+.
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Concepts Used:
Chemical Bonding and Molecular Structure
Such a group of atoms is called a molecule. Obviously, there must be some force that holds these constituent atoms together in the molecules. The attractive force which holds various constituents (atoms, ions, etc.) together in different chemical species is called a chemical bond.
Types of Chemical Bonds:
There are 4 types of chemical bonds which are formed by atoms or molecules to yield compounds.
- Ionic Bonds - Ionic bonding is a type of chemical bonding which involves a transfer of electrons from one atom or molecule to another.
- Covalent Bonds - Compounds that contain carbon commonly exhibit this type of chemical bonding.
- Hydrogen Bonds - It is a type of polar covalent bonding between oxygen and hydrogen wherein the hydrogen develops a partial positive charge
- Polar Bonds - In Polar Covalent chemical bonding, electrons are shared unequally since the more electronegative atom pulls the electron pair closer to itself and away from the less electronegative atom.
Factors Affecting Bond Enthalpy in Chemical Bonding:
- Size of the Atom
- Multiplicity of Bonds
- Number of Lone Pair of Electrons Present
- Bond Angle