Atomic Structure
1. Basic Concepts of Atomic Structure
Atom: The smallest unit of matter retaining the properties of an element.
Subatomic Particles:
Proton (p⁺): Positively charged, located in the nucleus, mass = 1 atomic mass unit (amu).
Neutron (n⁰): Neutral, located in the nucleus, mass ≈ 1 amu.
Electron (e⁻): Negatively charged, orbits the nucleus, mass ≈ 1/1836 of a proton.
2. Atomic Number, Mass Number, and Isotopes
Atomic Number (Z): Number of protons in the nucleus; defines the element.
Mass Number (A): Total number of protons and neutrons in the nucleus.
A = Z + N, where N is the number of neutrons.
Isotopes: Atoms of the same element with the same number of protons but different
numbers of neutrons.
Example: Hydrogen isotopes (Protium, Deuterium, Tritium).
3. Atomic Models
a. Dalton’s Atomic Theory (1803):
Atoms are indivisible and indestructible.
Atoms of the same element are identical.
Compounds are formed by combinations of different atoms.
b. Thomson’s Model (1897):
Discovered electrons.
Proposed the "plum pudding model": Electrons embedded in a positively charged sphere.
.c Rutherford’s Model (1911):
Discovered the nucleus through the gold foil experiment.
1. Basic Concepts of Atomic Structure
Atom: The smallest unit of matter retaining the properties of an element.
Subatomic Particles:
Proton (p⁺): Positively charged, located in the nucleus, mass = 1 atomic mass unit (amu).
Neutron (n⁰): Neutral, located in the nucleus, mass ≈ 1 amu.
Electron (e⁻): Negatively charged, orbits the nucleus, mass ≈ 1/1836 of a proton.
2. Atomic Number, Mass Number, and Isotopes
Atomic Number (Z): Number of protons in the nucleus; defines the element.
Mass Number (A): Total number of protons and neutrons in the nucleus.
A = Z + N, where N is the number of neutrons.
Isotopes: Atoms of the same element with the same number of protons but different
numbers of neutrons.
Example: Hydrogen isotopes (Protium, Deuterium, Tritium).
3. Atomic Models
a. Dalton’s Atomic Theory (1803):
Atoms are indivisible and indestructible.
Atoms of the same element are identical.
Compounds are formed by combinations of different atoms.
b. Thomson’s Model (1897):
Discovered electrons.
Proposed the "plum pudding model": Electrons embedded in a positively charged sphere.
.c Rutherford’s Model (1911):
Discovered the nucleus through the gold foil experiment.
