Matter: Properties, States, Changes, and Atomic Theory

Posted on Mar 11, 2025 in Chemistry

Matter: Properties, States, and Transformations

Matter is anything that occupies space and has mass. Matter exhibits both general and characteristic properties.

General and Characteristic Properties of Matter

  • General properties are those whose values do not identify a specific substance.
  • Characteristic properties are those that have a unique and characteristic value for each substance.

The magnitude of any feature of matter, or the changes it can undergo, can be measured; that is, it can be expressed with a number and a unit.

The Scientific Method

The scientific method is a procedure followed by those working in science to study problems and reach conclusions that explain and predict observed phenomena and new facts. The scientific method follows a series of steps:

  1. Observation.
  2. Hypothesis development.
  3. Experimentation.
  4. Analysis of results.
  5. Definition and establishment of laws and theories.
  6. Publication of results.

Gas Laws

  • Boyle’s Law: When a gas undergoes a transformation at a constant temperature, the product of the pressure exerted by the gas and the volume it occupies (P * V) remains constant.
  • Gay-Lussac’s Law: When a gas undergoes transformations at a constant volume, the ratio between the pressure and the absolute temperature (P / T) remains constant.
  • Charles’s Law: When a gas undergoes transformations at constant pressure, the ratio of the gas volume and the absolute temperature (V / T) remains constant.

States of Matter and Their Properties

  • Solid state (properties): Constant shape, constant volume, does not expand, does not compress (examples: ice, sugar).
  • Liquid state (properties): Variable shape, constant volume, does not expand, compresses with difficulty (examples: water, oil).
  • Gaseous state (properties): Variable shape, variable volume, expands, compresses (examples: steam, air).

Kinetic Theory of Matter

The kinetic theory states that:

  • Matter is formed by particles that are held together more or less depending on their state of aggregation.
  • The particles move more or less freely, depending on the state. The faster they move, the higher the temperature of the substance.

Changes of state are an example of a physical phenomenon, because they do not alter the nature of matter, but only the state in which it is presented.

Phase Transitions

  • Melting point: The temperature at which the change from solid to liquid occurs throughout the entire mass of the solid. The melting point coincides with the solidification point.
  • Boiling point: The temperature at which the change from liquid state to gaseous state occurs throughout the entire mass of the liquid. The boiling point coincides with the condensation point.
  • Evaporation: The change from liquid state to gas that occurs only at the surface of the liquid.
  • Boiling: The change from liquid state to gas that takes place throughout the entire mass of the liquid.

Separation of Mixtures

  • Sieving: Separation of mixtures of various solid particles with different sizes.
  • Filtration: Separation of a solid and a liquid when the solid is insoluble in the liquid.
  • Crystallization: Separation of a solid dissolved in a liquid by evaporation of the liquid.
  • Magnetic separation: Separation of two components when one is ferromagnetic.
  • Decantation: Separation of two immiscible liquids.
  • Distillation: Separation of two miscible liquids or a liquid in which a solid is dissolved.
  • Chromatography: Separation of mixtures whose components have different affinities for a solvent.

Solutions

A solution is a homogeneous mixture of two or more components: the solvent, which is the component present in the greater proportion, and the solute, which is the component present in a lower proportion.

Dalton’s Atomic Theory

  • Matter is made up of atoms, which are indivisible and indestructible particles.
  • All atoms of the same chemical element are equal in mass and other properties, and different from the atoms of any other element.
  • Compounds are formed by combinations of atoms of different elements.

Composition of Matter

Matter is made up of pure substances (elements and compounds) and mixtures (heterogeneous and homogeneous).

Concentration of Solutions

  • Dilute: Small ratio of solute to solvent.
  • Concentrated: Large ratio of solute to solvent.
  • Saturated: Does not support a greater amount of solute.

States Changes

States: Solid (melting) → Liquid (vaporization) → Gas (reverse sublimation) → Solid (sublimation) → Gas (condensation) → Liquid (solidification) → Solid

Calculations with Moles

  • Mole-amount: Atomic mass in grams.
  • Molecules: Result of the previous step multiplied by 6.022 x 1023.
  • Atoms: Number of molecules multiplied by the number of atoms in the molecule.
  • %: (Solute / Solution) * 100.
  • Molecular weight: Not directly addressed here.