Lesson 1.1: Particulate Nature of Matter

Lesson 1.1: Particulate Nature of Matter

• Matter is anything that has mass and volume
• Matter exists in various states: solid, liquid, or gas
• Different states of matter have varying characteristics, but all are made up of tiny moving particles
• These tiny particles determine the characteristics of the matter
• Dust, produced when wood is cut, is an example of matter exhibiting particulate nature
• The particles have unique arrangement and motion

Ancient Views on Matter

• Ancient Greek philosophers first speculated about the nature of matter
• They attempted to explain the nature of materials but lacked the ability to conduct experiments to validate their assumptions
• Thales proposed water as the basic element
• Anaximenes proposed air as the basic element
• Heraclitus proposed fire as the basic element
• Empedocles proposed four fundamental elements: water, air, fire, and earth

How do Ancient Philosophers View Matter?

• Greek philosophers agreed that all matter was made up of a single primal element
• Thales believed water was the primal element
• Anaximenes believed air was the primal element
• Heraclitus believed fire was the primal element
• Empedocles combined previous ideas, proposing that matter is made up of four elements (water, air, fire, and earth)

Particulate Nature of Matter (continued)

• Democritus proposed the concept of atom, the smallest indivisible particle of matter
• The idea of Democritus led to the understanding of matter being made up of tiny particles
• There are four key ideas
  • Matter is composed of discrete particles
  • There is empty space between the particles
  • The particles are in constant motion
  • There are forces acting between the particles

Discrete Particles of Matter

• Atoms are the building blocks of matter
• Atoms can be neutral, positively charged (cation), or negatively charged (anion)
• Molecules are formed when two or more atoms bond chemically
• Ions are charged atoms or groups of atoms

Macroscopic Level View of Matter

• Matter can be easily described at macroscopic level
• For instance, a table is made up of wood with nails attached to it
• However, the individual particles that make up a wood are hard to see at this level

Empty Space Between Particles

• The particulate nature of matter disproves that there is no empty space between particles
• Particles in matter have space between them, which varies in size depending on the type of matter
• An example: adding food coloring to water shows the empty spaces between water molecules

Motion of Particles

• Particles in matter are in constant motion
• The speed and direction of particle movement vary depending on the type of matter
• The space between particles also influences the movement, with more space allowing for faster and more random movement

Effect of Temperature on Particle Movement

• Increasing the temperature of matter causes particles to gain kinetic energy
• This leads to a faster movement
• The diagram shows the increase in kinetic energy when the temperature increases

Forces Between Particles

• Particles in matter are held together by intermolecular forces
• These forces can be attractive or repulsive
• Attractive forces maintain the shape of matter, like water droplets on a cold drink glass
• Repulsive forces exist between water molecules and glass particles

Arrangement of Particles in Solid, Liquid, and Gases

• Solids have closely packed particles arranged in an orderly manner
• Liquids have particles close together but are less orderly than solids
• Gases have particles far apart from one another and are randomly arranged

Intermolecular Forces

• The limited space in the particles of solids is due to strong attractive forces between them
• These forces keep the particles closely packed, resulting in solids maintaining shape and volume with low compressibility and fluidity
• Liquids have moderate attractive forces, thus allowing them to flow
• Gases have weak attractive forces, having minimal forces between particles. Consequently, they are compressible and flow easily

General Properties of Matter

• Mass: the amount of matter in an object
• Volume: the amount of space matter occupies
• Weight: the force of gravity acting upon an object;
• Density: the amount of mass per unit volume
• Specific Gravity: compares the density of a substance to the density of water

Weight

• Mass and weight are distinct but often confused
• Mass remains constant regardless of location or gravity
• Weight is the force of gravity acting on an object and changes with location and gravitational force

Volume

• Volume is the amount of space an object occupies
• Volume can be measured using instruments or calculating the dimensions of objects

Density

• Density is the ratio of mass to volume
• Higher density means more mass in a smaller volume
• Common substances have varying densities

Chemical Properties of Matter

• Chemical properties can only be observed when a substance undergoes a chemical change.
• Biodegradability: the capacity of a substance to decompose through microorganisms
• Combustibility / Flammability: the ability of a substance to burn when exposed to a certain amount of heat and oxygen

Flammability and Combustibility

• Flammability and combustibility describe the ability of a substance to burn
• Combustion is the rapid reaction of a substance with oxygen producing heat and light
• Combustibility is the ability of a substance to combust given appropriate conditions
• Flammability is the ability of a substance to ignite given a source of ignition

Pure Substances and Mixtures

• Matter can be classified as pure substances or mixtures based on its composition
• Pure substances have a fixed composition
• Mixtures are combinations of two or more substances

Elements

• Elements are the simplest substances
• They are made up of only one kind of atom
• Various elements have distinct properties

Compounds

• Compounds are substances formed by the chemical combination of two or more elements
• They have properties different from the elements they are composed of

Homogeneous Mixtures

• Have components evenly distributed throughout
• Examples: solutions (solid dissolved in liquid, gases in gases, liquids in liquids)

Heterogeneous Mixtures

• Have components unevenly distributed throughout
• Examples: suspensions, colloids (colloidal mixtures)

Separation of Mixtures

• Various techniques separate mixtures based on differences in physical and chemical properties
• Evaporation, crystallization, distillation, chromatography, and filtration are common techniques
• Manual separation methods include picking, sieving, and using magnets
• Centrifugation is used to separate materials based on density