Shortcut Methods

Typical Numerical Values for Structure of Atom-B Topic in neet and CBSE Board Exams#

1. Atomic Number (Z):

• Hydrogen (H): Z = 1
• Helium (He): Z = 2
• Carbon (C): Z = 6
• Sodium (Na): Z = 11
• Oxygen (O): Z = 8
• Aluminum (Al): Z = 13

2. Mass Number (A):

• Carbon-12 (C-12): A = 12
• Nitrogen-14 (N-14): A = 14
• Oxygen-16 (O-16): A = 16
• Sodium-23 (Na-23): A = 23
• Aluminum-27 (Al-27): A = 27
• Uranium-238 (U-238): A = 238

3. Number of Neutrons (N):

• Carbon-12 (C-12): N = 6
• Nitrogen-14 (N-14): N = 7
• Oxygen-16 (O-16): N = 8
• Sodium-23 (Na-23): N = 12
• Aluminum-27 (Al-27): N = 14

4. Isotopes:

• Carbon-12 (C-12), Carbon-13 (C-13), and Carbon-14 (C-14) are isotopes of carbon.
• Nitrogen-14 (N-14), Nitrogen-15 (N-15), and Nitrogen-16 (N-16) are isotopes of nitrogen.

5. Electron Configurations:

• Hydrogen: 1s¹
• Helium: 1s²
• Carbon: 1s², 2s², 2p²
• Sodium: 1s², 2s², 2p⁶, 3s¹
• Oxygen: 1s², 2s², 2p⁴
• Aluminum: 1s², 2s², 2p⁶, 3s², 3p¹

6. Quantum Numbers:

• For a 2s electron: n = 2, l = 0, ml = 0, ms = +1/2 or -1/2
• For a 3d electron: n = 3, l = 2, ml = -2, -1, 0, 1, or 2, ms = +1/2 or -1/2

7. Atomic Radii:

• Hydrogen: 53 pm
• Helium: 31 pm
• Carbon: 77 pm
• Nitrogen: 74 pm
• Oxygen: 66 pm
• Aluminum: 143 pm

8. Ionization Energy:

• Hydrogen: 1312 kJ/mol
• Helium: 2372 kJ/mol
• Carbon: 1086 kJ/mol
• Nitrogen: 1402 kJ/mol
• Oxygen: 1314 kJ/mol
• Aluminum: 579 kJ/mol

9. Electron Affinity:

• Hydrogen: -72.8 kJ/mol
• Helium: 0 kJ/mol (No electron affinity)
• Carbon: -122 kJ/mol
• Nitrogen: -4 kJ/mol
• Oxygen: -141 kJ/mol
• Aluminum: 43.9 kJ/mol

10. Nuclear Structure:

• Proton mass: ~1.6726 x 10⁻²⁷ kg (1 atomic mass unit)
• Neutron mass: ~1.6749 x 10⁻²⁷ kg
• Strong force: Mediated by gluons, holds protons and neutrons together in the nucleus
• Weak force: Responsible for certain types of radioactive decay and neutrino interactions
• Radioactive decay: Processes such as alpha, beta, and gamma decay that transform unstable nuclei