Chemistry Quiz Grade 8

Atomic Structure

• Atom: The smallest unit of matter that retains the properties of an element.
• Subatomic particles: Protons, neutrons, and electrons.
• Protons: Positively charged particles found in the nucleus.
• Neutrons: Neutrally charged particles found in the nucleus.
• Electrons: Negatively charged particles that orbit the nucleus in electron shells.
• Atomic Number: Represents the number of protons in an atom's nucleus. It determines the atom's identity.
• Atomic Mass: Represents the total number of protons and neutrons in an atom’s nucleus.
• Isotopes: Atoms of the same element with the same number of protons but varying numbers of neutrons.

Fundamental Particles

• Quarks: Fundamental particles that make up protons and neutrons.
• Gluons: Fundamental particles that bind quarks together.
• Leptons: Fundamental particles that include electrons and neutrinos.

Periodic Table

• Atomic Number: The number of protons in an atom's nucleus, which defines the element.
• Atomic Mass: The total mass of an atom, approximately equal to the sum of protons and neutrons.

Density

• Density: A measure of mass per unit volume. It reflects how tightly packed the particles in a substance are.
• Formula: Density = Mass / Volume.

Buoyancy

• Buoyant Force: An upward force exerted by a fluid on an object submerged in it.
• Archimedes' Principle: The buoyant force on an object submerged in fluid is equal to the weight of the fluid displaced by the object.

Kinetic Molecular Theory

• Explains the behavior of gases and liquids at the microscopic level.
• Key points:
  • Molecules are in constant random motion.
  • The average kinetic energy of molecules is proportional to the absolute temperature.
  • Collisions between molecules are perfectly elastic.

Viscosity

• Viscosity: A fluid's resistance to flow. Higher viscosity means a thicker fluid.
• Cohesion: Attractive forces between molecules of the same substance.
• Adhesion: Attractive forces between molecules of different substances.