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Isotopes
- Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
- As a result, isotopes have the same atomic number but different mass numbers.
- Examples of isotopes include:
- Hydrogen: Protium (¹H), Deuterium (²H), Tritium (³H).
- Carbon: Carbon-12 (¹²C), Carbon-13 (¹³C), Carbon-14 (¹⁴C).
- Isotopes exhibit identical chemical properties but different
Quantum Numbers
- Quantum numbers describe the state and position of an electron in an atom.
- There are four quantum numbers:
- Principal Quantum Number (n): Indicates the main energy level or shell of the electron.
- Azimuthal Quantum Number (l): Defines the subshell and shape of the orbital (0 for s, 1 for p, 2 for d, 3 for f).
- Magnetic Quantum Number (ml): Specifies the orientation of the orbital in space.
- S
Bohr's Model of the Atom
- Proposed by Niels Bohr in 1913.
- Based on Rutherford’s model and Planck's quantum theory.
- Electrons revolve around the nucleus in fixed circular paths called orbits or energy levels.
- These energy levels are represented as n = 1, 2, 3, ... (principal quantum numbers).
- Each orbit has a fixed amount of energy, and electrons do not radiate energy while in a stable orbit.
- Electrons can transition betwee
Dalton's Atomic Theory
- Proposed by John Dalton in 1803.
- It was the first scientific theory to describe the nature of matter in terms of atoms.
- Matter is made up of small, indivisible particles called atoms.
- Atoms of a given element are identical in size, mass, and other properties.
- Atoms of different elements differ in size, mass, and other properties.
- Atoms cannot be created, divided, or destroyed during chemical reactions.
- Atoms combine in simple whole-number ratios to form
Protons
- The proton is a positively charged particle with a relative charge of +1.
- The atomic number is determined by the number of protons in the nucleus.
- Protons were discovered by Ernest Rutherford in 1917.
- The charge of a proton is +1.6 × 10⁻¹⁹ coulombs.
- Protons are part of the nucleus and contribute to the atom's mass.
Neutrons
- The neutron has no charge, making it neutral