The longest wavelength of light that can be used for the ionisation of lithium atom (Li) in its ground state is \(x × 10^{–8}\ m\). The value of \(x\) is ______. (Nearest Integer)
(Given : Energy of the electron in the first shell of the hydrogen atom is \(2.2 \times 10^{–18} J\);
\(h = 6.63 × 10^{–34}Js\) and \(c = 3 × 10^8 ms^{–1}\))
(Given : Energy of the electron in the first shell of the hydrogen atom is \(2.2 \times 10^{–18} J\);
\(h = 6.63 × 10^{–34}Js\) and \(c = 3 × 10^8 ms^{–1}\))
Correct Answer: 4
Solution and Explanation
Energy required for ionisation of Li atom,
\(= 2.2 × 10^{–18}×\frac 94\)
J [Assume this formula is True for Li atom]
\(∵ E = \frac {hc}{λ}\)
\(2.2 \times 10^{-18} \times \frac 94 = \frac {6.63 \times 10-34 \times3 \times 10^8}{λ}\)
\(λ = 4 \times 10^{-8} m\)
So, the answer is \(4\).
Top Questions on Structure of atom
- The energy associated with electron in first orbit of hydrogen atom is \(-2.18 \times 10^{-18}\) J. The frequency of the light required (in Hz) to excite the electron to fifth orbit is (\(h=6.6 \times 10^{-34}\) Js)
- TS EAMCET - 2025
- Chemistry
- Structure of atom
- Isotopes of an element have a different number of
- UPCATET - 2025
- Physics
- Structure of atom
- The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom is –
- UPCATET - 2025
- Physics
- Structure of atom
- An element 'M' has 25% of the electrons filled in the third shell as in the second shell. The element 'M' is :
- CBSE Class X - 2025
- Science
- Structure of atom
- Which of the following is correct about the stability of half-filled and completely filled subshells?
(i) Relatively small shielding
(ii) Larger coulombic repulsion energy
(iii) Smaller exchange energy
(iv) Smaller coulombic repulsion energy
(v) Larger exchange energy- KEAM - 2025
- Chemistry
- Structure of atom
Questions Asked in JEE Main exam
In the first configuration (1) as shown in the figure, four identical charges \( q_0 \) are kept at the corners A, B, C and D of square of side length \( a \). In the second configuration (2), the same charges are shifted to mid points C, E, H, and F of the square. If \( K = \frac{1}{4\pi \epsilon_0} \), the difference between the potential energies of configuration (2) and (1) is given by:
- JEE Main - 2025
- Electromagnetic Field (EMF)
Given below are two statements:
Statement I:
will undergo alkaline hydrolysis at a faster rate than 
Statement II:
In
intramolecular substitution takes place first by involving lone pair of electrons on nitrogen.
- JEE Main - 2025
- Organic Chemistry
The effect of temperature on the spontaneity of reactions are represented as: Which of the following is correct?
- JEE Main - 2025
- Thermodynamics and Work Done
- Let \( \vec{a} = \hat{i} + 2\hat{j} + \hat{k} \) and \( \vec{b} = 2\hat{i} + 7\hat{j} + 3\hat{k} \). Let \( L_1 : \vec{r} = (-\hat{i} + 2\hat{j} + \hat{k}) + \lambda \vec{a}, \lambda \in {R} \) and \( L_2 : \vec{r} = (\hat{j} + \hat{k}) + \mu \vec{b}, \mu \in \mathbb{R} \) be two lines. If the line \( L_3 \) passes through the point of intersection of \( L_1 \) and \( L_2 \), and is parallel to \( \vec{a} + \vec{b} \), then \( L_3 \) passes through the point:
- JEE Main - 2025
- Vectors
If all the words with or without meaning made using all the letters of the word "KANPUR" are arranged as in a dictionary, then the word at 440th position in this arrangement is:
- JEE Main - 2025
- permutations and combinations
Concepts Used:
Structure of Atom
Atomic Structure:
The atomic structure of an element refers to the constitution of its nucleus and the arrangement of the electrons around it. Primarily, the atomic structure of matter is made up of protons, electrons and neutrons.
Dalton’s Atomic Theory
Dalton proposed that every matter is composed of atoms that are indivisible and indestructible.
The following are the postulates of his theory:
- Every matter is made up of atoms.
- Atoms are indivisible.
- Specific elements have only one type of atoms in them.
- Each atom has its own constant mass that varies from element to element.
- Atoms undergo rearrangement during a chemical reaction.
- Atoms can neither be created nor be destroyed but can be transformed from one form to another.
Cons of Dalton’s Atomic Theory
- The theory was unable to explain the existence of isotopes.
- Nothing about the structure of atom was appropriately explained.
- Later, the scientists discovered particles inside the atom that proved, the atoms are divisible.
Subatomic Particles
- Protons - are positively charged subatomic particles.
- Electron - are negatively charged subatomic particles.
- Neutrons - are electrically neutral particles and carry no charge
Atomic Structure of Isotopes
Several atomic structures of an element can exist, which differ in the total number of nucleons.These variants of elements having a different nucleon number (also known as the mass number) are called isotopes of the element. Therefore, the isotopes of an element have the same number of protons but differ in the number of neutrons. For example, there exist three known naturally occurring isotopes of hydrogen, namely, protium, deuterium, and tritium.