Atoms

• What are the tiny and indestructible particles that matter is composed of according to Dalton's Atomic Theory?


  Atoms
• According to Dalton's Atomic Theory, how do atoms of a given element compare to each other?

  All atoms of a given element are identical
• What does Dalton's Atomic Theory state about how atoms combine?

  Atoms can combine with other atoms in simple specific ratios
• What is the implication of Dalton's Atomic Theory regarding chemical reactions?

  Chemical reactions only involve separation, combination, or rearrangement of atoms; no atoms are created nor destroyed
• What is the Law of Definite Proportions as proposed by Joseph Louis Proust?

  Any sample of a specific compound will always have the same proportion of elements by mass, regardless of its source or size
• What does the Law of Multiple Proportions state?

  When two elements form more than one compound, the ratios of the masses of the second element that combine with a fixed mass of the first element are in small whole numbers
• What are atoms described as in the context of matter?

  Atoms are the fundamental building blocks of matter, capable of forming compounds when bonded together
• What is the origin of the word "atom"?

  The word "atom" is derived from the Greek word "atomos," meaning indivisible
• What is the smallest unit of an element that can engage in chemical reactions?

  Atoms
• How is a water molecule (H₂O) formed?

  A water molecule is made by chemically bonding two hydrogen atoms to one oxygen atom
• What is the charge of a proton?

  Positively charged (+)
• What is the charge of a neutron?

  No charge (neutral)
• What is the charge of an electron?

  Negatively charged (-)
• What is an isotope?

  Atoms with the same number of protons but different numbers of neutrons
• What is an isotone?

  Atoms with the same number of neutrons
• What is an isobar?

  Atoms with the same mass number but different atomic numbers
• Democritus: Introduced the concept of "atomos," meaning indivisible.
• Dalton: Proposed the "Billiard Ball Model," where atoms are solid, indivisible spheres.
• Thomson: Developed the "Raisin Bread Model," where electrons are embedded within a positively charged atom.
• Rutherford: Discovered the nucleus with the "Gold Foil Experiment," identifying that protons reside in the nucleus.
• James Chadwick: Discovered the neutron, a neutral particle within the nucleus.
• Bohr: Proposed the "Planetary Model," where electrons orbit the nucleus in defined paths.
• Schrödinger: Developed the "Quantum Mechanical Model," which describes electron positions in a 3D probabilistic space rather than fixed orbits.
• Principal Quantum Number (n) - describes the MAIN ELECTRON SHELL and the SIZE of the electron cloud.

  Angular / Azimuthal Quantum Number (l) - describes the SUBSHELL  & the SHAPE of the electron cloud

  Magnetic Quantum Number (Ml) - describes the ORBITAL or ORIENTATION in space

  Spin (Ms or s) - describes the angular momentum of an electron.

  1. Aufbau’s Principle: Electrons occupy the lowest energy orbitals first.
  2. Pauli Exclusion Principle: No two electrons in an atom can have the same set of four quantum numbers.
  3. Hund’s Rule: Electrons will fill degenerate orbitals singly before pairing up.