Comprehensive Guide to Matter: Properties, Classifications, and States

Definition of Chemistry: Chemistry is defined as the study of matter and the changes it undergoes.
Definition of Matter: Matter is anything that occupies space and has mass.
Scope of Study: Almost anything imaginable is composed of matter, making it a subject of study within the field of chemistry.

Introduction: All matter possesses distinct physical and chemical properties.
Physical Properties: - Defined as properties that can be measured or observed without altering the chemical composition of the matter. - Physical properties are categorized into two subgroups: extensive and intensive properties.
Extensive Properties: - These properties depend on the specific amount of matter being measured. - Examples: - Mass - Volume - Number of moles. - Practical Application: Reducing the amount of matter being weighed will directly decrease the measured mass.
Intensive Properties: - These properties are independent of the amount of matter present. - Examples: - Color - Melting point - Boiling point - Density. - The Case of Density: The density of water remains constant regardless of volume; whether measuring $1\,mL$ or $1\,L$ , the density stays the same at a specific temperature.
Chemical Properties: - These describe the characteristic ability of a substance to undergo reactions to form entirely new substances. - Examples: - Flammability - Susceptibility to corrosion.

Matter is generally classified into two main categories: pure substances and mixtures.
Pure Substances: - Defined as forms of matter with a definite composition and distinct properties. - Pure substances are further divided into elements and compounds.
Elements: - A substance that cannot be broken down into simpler substances through chemical means. - There are currently $118$ known elements following the synthesis of Oganesson ( $Og$ ). - Oganesson ( $Og$ ): - Its synthesis completed the modern periodic table. - Scientists are currently working on ways to further extend the periodic table. - It is the heaviest element in the periodic table. - It is the $2^{nd}$ element ever named after a living person (the first being Seaborgium). - It is named after Yuri Tsolakovich Oganessian, a Russian nuclear physicist and lead researcher in superheavy elements.
Compounds: - Formed when two or more types of elements are combined in a fixed proportion to create a single substance.

Mixtures: - A combination of two or more substances where each substance retains its own distinct identity. - Mixtures are subdivided into homogeneous and heterogeneous categories.
Homogeneous Mixtures: - The composition is uniform throughout the mixture. - Individual components cannot be recognized or distinguished. - Example: Dissolving table salt in a glass of water creates a solution.
Components of a Solution: - Solvent: The component present in the greatest amount. - Solute(s): The component or components existing in minor amounts. - Aqueous Solutions: This term signifies that water acts as the solvent in the solution.

Heterogeneous Mixtures: - The individual components of the mixture can be differentiated. - These are subdivided into suspensions and colloids.
Suspensions: - Example: Adding a scoop of sand to a glass of water. Because water cannot dissolve sand, the sand is distinguishable from the water. - Characteristics: The particles in a suspension are large enough that they eventually settle to the bottom.
Colloids: - Colloids can be deceptive because they often appear as solutions at first glance. - Example: Fresh Milk: Milk appears to be a single liquid phase, but under a microscope, it reveals globules suspended in a liquid matrix. This is because milk is made of fats and water, which do not mix completely. - Particle Size: Colloid particles are small enough to remain dispersed within their matrix, typically ranging from $1$ to $1000\,nm$ .

Terminology in Colloid Chemistry: - Dispersed Phase: The component(s) being dispersed. - Continuous Phase (Dispersion Medium): The component in which the particles are dispersed. - Hydrocolloid: A specific colloidal system where water is the dispersion medium.
The Tyndall Effect: - A simple method to differentiate a colloid from a solution using a flashlight. - In a colloid, the dispersed phase scatters the beam of light. - In a solution, the light is cleanly transmitted without scattering.
Table of Colloid Types:
1. Solid sol: Dispersed phase: Solid; Continuous phase: Solid (Examples: steel, opal).
2. Solid emulsion or Gel: Dispersed phase: Liquid; Continuous phase: Solid (Examples: butter, cheese).
3. Solid foam: Dispersed phase: Gas; Continuous phase: Solid (Examples: plastic foam, lava).
4. Sol: Dispersed phase: Solid; Continuous phase: Liquid (Examples: milk of magnesia, paint).
5. Emulsion: Dispersed phase: Liquid; Continuous phase: Liquid (Examples: mayonnaise, milk).
6. Foam: Dispersed phase: Gas; Continuous phase: Liquid (Examples: whipped cream, soap suds).
7. Solid Aerosol: Dispersed phase: Solid; Continuous phase: Gas (Examples: smoke). 8. Liquid Aerosol: Dispersed phase: Liquid; Continuous phase: Gas (Examples: fog, mist).

Modern Classification: While science has advanced to identify a total of $22$ known states of matter, study usually focuses on four basic states.
Solids: - Molecules or atoms are arranged in a regular, repeating manner and are fixed in position. - They maintain their own shape and do not conform to the shape of their container.
Liquids: - Molecules can move freely, though they are compact and movement is restricted. - They lack a fixed shape and copy the shape of their container.
Gases: - Molecules move freely and are made up of neutral atoms or molecules. - Like liquids, they copy the shape of their container.
Plasma: - Described as a "charged gas." - Unlike standard gas, which is neutral, plasma consists of charged molecules or atoms. - Occurrence: Requires extremely harsh conditions (extremely hot environments). - Observation: Found on the surface of stars. - Note on Education: Historically, plasma was not always taught as a standard state of matter alongside solid, liquid, and gas in elementary or high school curriculums.