Basic Unit of Matter: Atoms are the fundamental building blocks of matter.

• Composition: An atom consists of three primary subatomic particles:

Protons: Positively charged particles located in the nucleus.

Neutrons: Neutrally charged particles found in the nucleus.

• Electrons: Negatively charged particles that orbit the nucleus in electron shells.

• Atomic Number: The number of protons in the nucleus, which defines the element.

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

• Element Identity: The type of element is determined by the number of protons (atomic number).

• Isotopes: Atoms of the same element with different numbers of neutrons, leading to different mass numbers.

• Electron Configuration: Electrons are arranged in energy levels (shells) around the nucleus, influencing chemical

  properties and reactivity

• Chemical Bonding: Atoms bond with other atoms to form molecules, either through ionic bonds (electron transfer) or covalent bonds (electron sharing).

• Stability: An atom is most stable when its outer electron shell is full, leading to the concept of the octet rule.

• Atomic Theory: The modern atomic model is based on quantum mechanics, where electrons exist in probability.

• rather than fixed orbits.