Matter Flashcards
What is matter in the context of physics?
Matter is anything that has mass and occupies space (volume).
What is the difference between mass and weight?
Mass is the amount of matter in an object (in kilograms). Weight is the force due to gravity acting on that mass (in newtons).
Name the three primary states of matter and give a brief description of each.
- Solid: Particles packed closely in a rigid structure.
- Liquid: Particles relatively free to move; takes shape of its container.
- Gas: Particles move freely, filling the available volume.
Give two examples of changes of state and name the processes.
Melting: Solid to liquid.
Evaporation/Boiling: Liquid to gas.
Condensation: Gas to liquid.
Freezing: Liquid to solid.
Sublimation: Solid to gas.
How is density defined, and what is its formula?
Density is mass per unit volume.
Formula: ρ = m/V.
What is specific gravity?
Specific gravity is the ratio of a substance’s density to the density of a reference substance (usually water).
What is the difference between an atom and a molecule?
Atom: The smallest particle of an element that retains its chemical properties.
Molecule: A group of two or more atoms bonded together, representing the smallest unit of a compound.
Define element and compound.
Element: A substance made of only one type of atom (e.g., O₂, Fe).
Compound: A substance formed by the chemical combination of two or more elements (e.g., H₂O).
How do mixtures differ from pure substances?
Mixtures: Two or more substances blended but not chemically combined; can often be separated by physical means.
Pure Substances: Have a uniform composition (elements or compounds).
What do atomic number and mass number represent?
Atomic number (Z): Number of protons in the nucleus.
Mass number (A): Total number of protons + neutrons in the nucleus.
What are isotopes?
Isotopes are variants of an element with the same number of protons but different numbers of neutrons (thus different mass numbers).
Explain the difference between ionic and covalent bonds.
Ionic Bonds: Formed by the transfer of electrons between atoms (e.g., NaCl).
Covalent Bonds: Formed by sharing electrons between atoms (e.g., H₂O).
State the Law of Conservation of Mass.
Law of Conservation of Mass: In a closed system, mass is neither created nor destroyed during chemical or physical changes.
What does the kinetic molecular theory say about particles in matter?
It states that particles (atoms/molecules) are always in motion; the higher the temperature, the faster they move. This motion underlies changes of state and gas behavior.
Why do most substances expand when heated?
When heated, particles gain kinetic energy and vibrate/move more, increasing the average distance between them, leading to expansion.
What is plasma, often referred to as the “fourth state of matter”?
Plasma is an ionized gas containing free electrons and ions, found in stars and lightning. It is electrically conductive and distinct from solid, liquid, and gas.
Give an example of a physical change and a chemical change.
Physical Change: Changes in state or form without altering composition (e.g., ice melting).
Chemical Change: Substance transforms into one or more new substances (e.g., iron rusting).
Differentiate between elasticity and plasticity.
Elasticity: Ability of a material to return to its original shape after the deforming force is removed.
Plasticity: Tendency to retain a deformed shape once the force is removed.
State Hooke’s Law.
Hooke’s Law: The extension (or compression) of a spring is proportional to the applied force.
Define stress and strain in materials.
Stress: Force per unit area.
Strain: Deformation per unit length.
Give the definitions of hardness and ductility.
Hardness: A material’s resistance to deformation or scratching.
Ductility: A material’s ability to be drawn into a wire without breaking.
What do malleability and brittleness refer to?
Malleability: A material’s ability to be flattened into thin sheets.
Brittleness: Tendency to break or shatter without significant deformation.
How is pressure in a fluid (liquid or gas) defined?
Pressure = Force per unit area. In fluids, pressure acts equally in all directions (Pascal’s Principle).
State Archimedes’ Principle.
A body immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces.
Differentiate between cohesion and adhesion in liquids.
Cohesion: Attraction between like molecules (e.g., water-water).
Adhesion: Attraction between unlike molecules (e.g., water-glass).
What is surface tension?
A property of liquids where the surface acts like an elastic membrane due to cohesive forces among molecules at the surface.
How does vapor pressure relate to boiling?
Boiling occurs when the vapor pressure of a liquid equals the external (atmospheric) pressure, allowing bubbles to form.
What is sublimation, and give one example.
Sublimation is the phase change from solid directly to gas (or vice versa) without passing through the liquid state.
Example: Dry ice turning into gas.
What does thermal conductivity describe?
Thermal conductivity describes how well a material conducts heat; high conductivity (e.g., metals) transfers heat quickly.
What is the difference between crystalline and amorphous solids?
Crystalline Solids: Atoms or molecules arranged in an orderly, repeating pattern.
Amorphous Solids: Atoms or molecules lack a long-range order (e.g., glass).
