Summary Structure of an atom and its nucleus

Structure of an Atom and its nucleus

🧬 Structure of an Atom
⚛️Basic Atom Model

An atom has two main parts:

1. Nucleus – center of the atom
2. Electron cloud – space around the nucleus where electrons are found



🧠 I. Subatomic Particles

Particle Symbol Charge Mass (amu) Location
Proton p+p^+ +1 1.0 Nucleus
Neutron n0n^0 0 1.0 Nucleus
Electron e−e^- –1 ~0.0005 Electron cloud

Note: The mass of electrons is so small it's often considered negligible in atomic mass
calculations.




🧲 II. Nucleus of the Atom
 Made of protons and neutrons
 Positively charged due to protons
 Most of the mass of the atom is here
 Very small and dense



🔢 III. Atomic Number (Z)

 The number of protons in the nucleus
 Determines the identity of the element
 Equal to number of electrons in a neutral atom

⚖️IV. Mass Number (A)

 The total number of protons + neutrons
 A=Z+NA = Z + N