Physics Lesson 1 Exercises

Atomic Theory

• Atoms are the fundamental building blocks of matter, originating from the Greek word "atomos," meaning indivisible.
• Democritus proposed that matter is composed of tiny, indivisible particles around 470 - 400 BC.
• John Dalton, known as the Father of Modern Atomic Theory, published his atomic theory in 1808, emphasizing the existence of atoms, their identical properties within elements, and the conservation of atoms during reactions.

Dalton's Atomic Theory

• Elements comprise very small, indivisible particles called atoms.
• Atoms of the same element have identical properties, differing from those of other elements.
• Atoms cannot be created or destroyed.
• Compounds arise from specific ratios of different atoms.
• The composition of compounds is consistent in relative proportions of atoms.

Relevant Laws

• Law of Definite Proportions (Joseph Proust): Same compound samples contain components in fixed proportions.
• Law of Multiple Proportions: When two elements form multiple compounds, the mass ratios of one combined with a fixed mass of the other are whole numbers.

Fundamental Particles

• Atoms consist of electrons, protons, and neutrons.
• J.J. Thomson discovered electrons in 1897 through cathode ray experiments and proposed the Plum-Pudding Model of the atom.
• Ernest Rutherford's Gold Foil Experiment (1911) revealed that:
  • Atoms are mostly empty space.
  • Most mass is concentrated in a dense, positively charged nucleus.
  • Electrons orbit surrounding the nucleus.

Nuclear Structure

• Protons carry a positive charge; their mass is roughly 1840 times that of electrons.
• Protons remain within the nucleus due to a strong nuclear force, which also binds neutrons and protons together.
• Weak nuclear force governs processes like beta decay.

Atomic Models

• Neils Bohr introduced the Planetary Model in 1913, defining fixed electron orbits with quantized energy levels.
• Erwin Schrödinger developed the Quantum Model, describing electron behavior via wave functions, quantifying electron energy levels through the Schrödinger equation.

Discovery of Neutrons

• James Chadwick discovered neutrons in 1932, showing they are electrically neutral and of similar mass to protons.

Atomic Number and Mass

• Atomic Number: Number of protons in an atom's nucleus.
• Mass Number: Total count of protons and neutrons; in neutral atoms, protons equal electrons.
• Isotopes are variations of elements with the same protons but different neutrons, yielding diverse atomic masses.

Molecules

• Molecules are the smallest units of compounds that retain stable properties.
• Can be diatomic (two atoms) or polyatomic (more than two atoms).

Ions

• Ions are atoms or groups with a net charge.
• Types of Ions:
  • Cations: Positive net charge.
  • Anions: Negative net charge.

Test your knowledge with these exercises from Physics Lesson 1. You'll tackle questions involving temperature conversions, mass calculations, and the definition of power. Improve your understanding of key physics concepts through practical problems.