Jaza

Definition:

• An atom is the smallest particle of an element that retains its chemical properties.

Structure:

• Atoms are made up of three main subatomic particles:

  • Protons - positively charged (+1)

  • Neutrons - no charge (neutral)

  • Electrons - negatively charged (–1)

Nucleus:

• The nucleus is the central part of the atom containing protons and neutrons.

• It carries a positive charge and contains most of the atom’s mass.

Atomic Number (Z):

• The number of protons in an atom.

• It determines the identity of the element.

Mass Number (A):

• The total number of protons and neutrons in the nucleus.

• Formula: Mass Number = Protons + Neutrons

  
  

• Number of electrons = number of protons in a neutral atom

Isotopes:

• Atoms of the same element having the same number of protons but different number of neutrons.

  
  

• Matter is made of tiny indivisible particles called atoms.

• Atoms of the same element are identical.

• Atoms combine in whole numbers to form compounds.

• Atoms are divisible (they contain smaller particles).

• Atoms of the same element may have different masses (isotopes).