Atomic Structure: A Chemistry Short Notes
Atom: The smallest particle of an element that can exist independently.
Components of an Atom:
- Nucleus:
- Contains protons and neutrons.
- Protons: Positively charged particles.
- Neutrons: Neutral particles.
- Electrons:
- Negatively charged particles.
- Revolve around the nucleus in specific energy levels or shells.
- Negatively charged particles.
Atomic Number and Mass Number:
- Atomic Number:
- The number of protons in the nucleus.
- Determines the identity of an element.
- Mass Number:
- The sum of protons and neutrons in the nucleus.
Isotopes:
- Atoms of the same element with different numbers of neutrons.
- Have the same atomic number but different mass numbers.
Electronic Configuration:
- The arrangement of electrons in the energy levels or shells around the nucleus.
- Follows specific rules (e.g., Aufbau principle, Hund's rule, Pauli exclusion principle).
Bohr's Model:
- A simplified model of the atom.
- Electrons move in fixed orbits around the nucleus.
- Each orbit corresponds to a specific energy level.
Quantum Mechanical Model:
- A more accurate model of the atom.
- Electrons exist as wave-particles.
- Their exact location cannot be determined, but their probability of being found in a certain region can be calculated.
Orbitals:
- Regions of space around the nucleus where there is a high probability of finding an electron.
- Types of orbitals: s, p, d, f.
Periodic Table:
- A tabular arrangement of elements based on their atomic number and electronic configuration.
- Groups (vertical columns): Elements with similar chemical properties.
- Periods (horizontal rows): Elements with the same number of electron shells.
Key Points to Remember:
- Atoms are composed of protons, neutrons, and electrons.
- The number of protons determines the identity of an element.
- Electrons occupy specific energy levels or shells around the nucleus.
- The periodic table organizes elements based on their atomic number and electronic configuration.
