Atomic Structure and Subatomic Particles

Atom Structure

• Atoms are the fundamental building blocks of all matter
• Matter is anything that occupies space and possesses mass
• Understanding atomic structure is key to comprehending the properties of matter

Subatomic Particles

• Atoms consist of smaller particles termed subatomic particles
• The most crucial subatomic particles for chemistry are electrons, protons, and neutrons

Properties of Subatomic Particles

Atom Neutrality

• Protons' number equals electrons' number in a neutral atom
• Neutrons, with no charge play no role in balancing the charge

Atomic Number

• Defined as the number of protons in an atom
• Uniquely identifies an element
• Example: Hydrogen's atomic number is 1, signifying 1 proton
• The atomic number determines the element, e.g., 2 protons = Helium, 29 protons= Copper

Mass Number

• Calculated by summing protons and neutrons in an atom's nucleus.
• Example: Hydrogen with mass number of 3 has 2 neutrons.
• Number of neutrons = Mass number - Atomic number

Determining Subatomic Particles

• Specific examples of elements (Li, Ne, Cl, K, and C) and their corresponding mass and atomic numbers are given showcasing calculation of the number of subatomic particles.

Bohr's Model

• The atom's center (nucleus) is positively charged
• Nucleus houses most of an atom's mass (protons + neutrons)
• Electrons exist in specific orbits (energy levels) surrounding the nucleus
• Each orbit can hold only a specific maximal number of electrons (2n²)

Electron Cloud Model

• This model depicts electrons as distributed within a region, or orbital, denoting their likelihood of presence, rather than fixed orbits.
• Probability-based unlike the fixed orbits of Bohr's Model
• Derived from mathematical equations

Quantum Numbers

• Scientists use quantum numbers to explain the location and behavior of electrons within an atom
• *Principal quantum number (n) indicates the main energy level
• *Angular momentum quantum number (l) determines the sublevel (s, p, d, f) and shape of orbital
• *Magnetic quantum number (m) identifies the orbital's orientation
• Atoms have a spin quantum number (+1/2, or –1/2)

Sublevel Names

• Corresponding names for the different angular momentum quantum numbers (l values) with their respective shapes (s, p, d, f).

Electron Configuration

• Defines the arrangement of electrons within an atom's energy levels and sublevels
• Energy levels (n = 1, 2, 3...) accommodate a maximal number of electrons (2n²).
• These levels are further divided into sublevels (s, p, d, f...), each holding a certain number of electrons.

Electron Configuration Priciples

• Aufbau principle: Electrons fill orbitals with the lowest energy first
• Pauli exclusion principle: Each subshell can only house a maximum of two electrons with opposite spins.
• Hund's rule: Empty orbitals will have one electron filling each before any orbital has two electrons.

Isotopes

• Atoms with an equal number of protons but varying neutron counts.
• Thus, isotopes have the same atomic number but a different mass number.

Elements

• Matter formed from a specific atom type
• Scientists have identified 90 naturally occurring elements and many artificial ones.
• Elements combine to create various substances in our world.

Explore the fundamental concepts of atomic structure and the properties of subatomic particles in this quiz. Understand how electrons, protons, and neutrons contribute to the overall properties of matter. Test your knowledge on atomic number and the neutrality of atoms.