Subatomic Particles Overview

Subatomic Particles Overview

• Subatomic particles are smaller than atoms, comprising protons, neutrons, and electrons.
• Atoms serve as the fundamental units of matter retaining element properties.

Protons

• Discovered by Ernest Rutherford in 1919 through alpha particle deflection experiments.
• Protons carry a positive charge and reside in the atom's nucleus.
• The atomic number equals the number of protons and determines an element’s identity.

Neutrons

• Discovered by James Chadwick in 1932, neutrons are neutral particles located in the nucleus with protons.
• Together, protons and neutrons account for nearly all atomic mass.
• Mass number equals the total number of protons and neutrons.

Electrons

• Electrons, negatively charged particles, orbit the nucleus at high speeds.
• Discovered by J.J. Thomson in 1897, they have a mass significantly smaller than protons and neutrons.
• The number of electrons is equal to the number of protons in a neutral atom.

Atomic Structure

• Nucleus: Comprises protons and neutrons; represents a small volume of the atom.
• Electrons occupy the space surrounding the nucleus, creating most of an atom's volume.
• Conceptual analogy: If an atom is a stadium, the nucleus is the size of a grain of sand.

Atomic Number and Mass Number

• Atomic number: Number of protons in the nucleus; equals the number of electrons in a neutral atom.
• Mass number: Sum of protons and neutrons; provides an estimate of atomic mass.

Isotopes

• Isotopes have the same atomic number (protons) but different mass numbers (neutrons).
• The existence of isotopes was confirmed through mass spectroscopy, identifying varied atom types per element.

Everyday Uses of Isotopes

• Cobalt-60: Used in cancer treatment.
• Iodine-131: Utilized for thyroid cancer therapy.
• Carbon-11: Employed in PET scans for medical imaging.
• Technetium-99: Commonly used in medical diagnostics.

Calculation Examples

• For 7 protons and 8 neutrons: Atomic symbol is represented as (^{15}_{7}\text{N}).
• For 11 protons and 13 neutrons: Atomic symbol can be expressed as (^{24}_{11}\text{Na}).
• For an atomic number of 14 with 15 neutrons: Atomic symbol is (^{29}_{14}\text{Si}).
• For 9 protons and mass number of 10: Atomic symbol is written as (^{10}_{9}\text{F}).