Matter: Classification, States, Properties, and Temperature

Classification of Matter and its Properties

Introduction to Matter

Definition: Matter is anything that has mass and occupies volume, regardless of its size.
Examples: Water, wood, plastic bags, medicine, aluminum cans.
Classification Basis: Matter can be classified by its composition, physical state, and other parameters.

Classification by Composition

Pure Substances

Definition: Substances that contain only one type of matter or are composed of two or more substances in a definite, fixed composition.
Types of Pure Substances:
- Elements:
 - Definition: Made up of only one type of atoms. (The term "type" is specific and refers to atoms with the same number of protons, allowing for isotopes).
 - Examples: Copper (Cu), Iron (Fe), Aluminum (Al), Magnesium (Mg), Calcium (Ca), Mercury (Hg).
 - Number: There are approximately $101-111$ different elements currently known.
 - Forms: Elements can exist in a dual form (e.g., individual atoms) or in combined forms, often as diatomic or polyatomic molecules (e.g., Hydrogen gas ( $H2$ ), Nitrogen gas ( $N2$ ), Oxygen gas ( $O_2$ )).
- Compounds:
 - Definition: Substances that consist of two or more different elements (or atoms of two or more different elements) chemically combined in a definite and fixed proportion.
 - Examples:
 - Water ( $H2O$ ): Always contains two hydrogen atoms for every one oxygen atom. If the ratio changes (e.g., $H2O_2$ ), it becomes a different substance.
 - Hydrogen Peroxide ( $H2O2$ ): Distinct from water, having a different composition and properties.
 - Table Salt (Sodium Chloride, NaCl): A compound of sodium (Na) and chlorine (Cl).
 - Sugar ( $C{12}H{22}O_{11}$ )
 - Quantity: There are an infinite number of compounds.
 - Types of Compounds:
 - Molecular Compounds: Substances made up of discrete molecules where atoms are present in definite proportions (e.g., Water ( $H2O$ ), Hydrogen gas ( $H2$ ), Carbon Dioxide ( $CO2$ ), Oxygen gas ( $O2$ ), Nitrogen gas ( $N_2$ )).
 - Inorganic Compounds / Salts: Collections of ions arranged in a crystal lattice, not forming definite, independent molecules (e.g., Table Salt (NaCl)). In NaCl, each sodium ion is typically surrounded by six chloride ions, and vice versa. There is a simplest ratio, but not a discrete molecule.
 - Organic Compounds: Compounds primarily based on carbon (e.g., proteins, DNA).
 - Formation/Decomposition: Compounds can be formed by combining elements under controlled conditions (e.g., Sodium metal + Chlorine gas $ ightarrow$ Sodium Chloride), or they can be split into their constituent elements.
 - Graphic Representation (Book Convention):
 - Hydrogen: White, light gray, or cyan.
 - Oxygen: Red.
 - Nitrogen: Blue.
 - Chlorine: Yellow.
 - Metals: Gray.
 - Importance of Arrangement: The arrangement of atoms within a compound (isomerism) can significantly affect its properties, even with the same number of atoms (e.g., different forms of sugar with $C{12}H{22}O_{11}$ ).

Mixtures

Definition: Substances that consist of two or more substances physically mixed but not chemically combined. They can be present in varying ratios and can be separated by physical methods.
Examples: Water and sugar, water and salt.
Types of Mixtures:
- Homogeneous Mixtures:
  - Definition: Mixtures that are thoroughly mixed and have a uniform composition throughout, even at the atomic or molecular scale. You would find the same composition at any point within the mixture.
  - Examples: Milk, soda (without ice cubes), brass (an alloy of copper and zinc, e.g., $10\%$ Copper), scuba breathing gas (oxygen, nitrogen, other gases).
- Heterogeneous Mixtures:
  - Definition: Mixtures where the composition varies from one part to another. There are clear partitions or visibly different components. You would find different substances if you moved from one point to another.
  - Examples: Soda with ice cubes (ice is a different physical state), paint (components may separate over time), oil rising in peanut butter.
Separation Techniques for Mixtures:
- Purpose: To separate components of a mixture, either qualitatively (identifying substances) or quantitatively (determining amounts).
- Filtration: Separates solid particles dispersed in a liquid (e.g., using a filter paper; liquid passes through, solid remains).
- Chromatography: Separates components of a solution based on their differential distribution between a stationary phase and a mobile phase (e.g., separating dyes in ink using paper chromatography, Gas Chromatography (GC), High-Performance Liquid Chromatography (HPLC) in pharmaceuticals).
- Magnetic Separation: Separates magnetic metals from non-magnetic substances (e.g., using a magnet to remove iron particles).
- Evaporation/Distillation: Separates a dissolved solid from a liquid by evaporating the liquid, leaving the solid behind (e.g., evaporating water to recover sodium chloride).

States and Properties of Matter

Physical States of Matter

Matter primarily exists in three physical states: solid, liquid, and gas.
Solids:
- Properties: Have a definite shape and a definite volume.
- Particle Arrangement: Particles (atoms, molecules, or ions) are held together by strong attractive forces in a fixed, rigid arrangement. They can only vibrate slowly in their fixed positions relative to their neighbors.
- Types:
  - Crystalline Solids: Have a regular, repeating, ordered arrangement of atoms (e.g., specific distances between similar atoms).
  - Amorphous Solids: Have an irregular, disordered arrangement of atoms.
Liquids:
- Properties: Have a definite volume but not a definite shape; they acquire the shape of the container they are placed in.
- Particle Arrangement: Particles are closely packed but are free to move around each other (moderate speed) in random directions. They exhibit transient interactions.
- Examples: Water, oil, milk.
Gases:
- Properties: Do not have a definite shape or a definite volume; they expand to fill the entire volume of their container and can be compressed under pressure (e.g., gas in a balloon or cylinder).
- Particle Arrangement: Molecules move rapidly at high speeds in random directions, and they are far apart from each other.
- Interactions: Gas molecules have very little to no interaction with each other due to the large distances between them; their size is often considered negligible compared to the distance to the nearest molecule.
- Pressure: The force generated by gas molecules hitting the walls of their container.

Summary of Physical States:

Property	Solid	Liquid	Gas
Shape	Definite	Indefinite	Indefinite
Volume	Definite	Definite	Indefinite
Particle Arrangement	Fixed, vibrating	Random, close	Random, far apart
Particle Interaction	Strong	Moderate	None/Very little
Particle Movement	Very little	Moderate	Very fast

Physical Properties

Definition: Characteristics of matter that can be observed or measured without changing the identity or chemical composition of the substance.
Examples:
- Physical State: Water as liquid at room temperature; copper as solid; oxygen as gas.
- Melting Point
- Boiling Point
- Odor / Smell
- Shininess / Luster: Some metals shine, some do not.
- Magnetic Properties: Some metals are magnetic, some are not.
- Color: Copper is reddish-orange.
- Conductivity: Excellent conductor of heat and electricity (e.g., copper).
- Density

Physical Changes

Definition: Changes in the physical state or appearance of a substance, where the composition of the matter remains the same. No new substance is formed.
Examples:
- Change of State: Ice melting into water, water boiling into steam (all are $H_2O$ ).
- Change of Shape: Hammering gold into a thin gold leaf, cutting a log into kindling, cutting paper into small pieces, cutting dough into strips.
- Dissolving: Sugar dissolving in water (forming a solution, but both retain their chemical identity).

Chemical Properties and Chemical Changes

Chemical Properties

Definition: Characteristics of a substance that describe its ability to undergo a chemical change, forming new substances.
Examples:
- Flammability: Paper's ability to burn.
- Reactivity: Silver's ability to tarnish (react with air).
- Rusting: Iron's tendency to rust in air and humidity.

Chemical Changes (Chemical Reactions)

Definition: Changes that alter the chemical composition of a substance, resulting in the formation of one or more new substances with entirely different physical and chemical properties.
Indicators: Formation of gas, change in color, release or absorption of heat, formation of a precipitate.
Examples:
- Caramelization: Sugar melting and caramelizing (molecular structure changes, creating new substances).
- Rusting: Iron reacting with oxygen and water to form rust (rust is a different substance from iron).
- Burning: A piece of wood burning (produces heat, ash, carbon dioxide, water vapor – all new substances).
- Burning a candle.
- Toasting a marshmallow.
- Shiny silver metal reacting with air to give a black, grainy coating.

Comparison of Physical and Chemical Changes

Property	Physical Change	Chemical Change
Composition	Remains the same	Changes; new substance(s) formed
Identity	Stays the same (e.g., water is still water)	New physical and chemical properties
Examples	Water boils, copper drawn into wire, sugar dissolves	Silver reacting with air, wood burns, sugar caramelizes

Temperature

Definition: A measure of the quantity of heat or energy a substance has. Pumping in heat raises temperature; taking heat out drops temperature.
Tool: Thermometer (various types, including digital).
Units: Celsius ( $^ ext{o}C$ ), Kelvin (K), Fahrenheit ( $^ ext{o}F$ ).
Importance: In science, Celsius and Kelvin are predominantly used, especially Kelvin for gas laws.

Temperature Scales and Conversions

Reference Points:
- Freezing Point of Water:
  - $0^ ext{o}C$
  - $32^ ext{o}F$
  - $273 K$ ( $273.15 K$ more precisely)
- Normal Body Temperature:
  - $37^ ext{o}C$
  - $98.6^ ext{o}F$
  - $310 K$
- Boiling Point of Water:
  - $100^ ext{o}C$
  - $212^ ext{o}F$
  - $373 K$
Celsius Scale Design: Based on freezing ($0^ ext{o}C) and boiling ($100^ ext{o}C) points of water, with $100$ divisions in between.
Fahrenheit Scale Design: $32^ ext{o}F$ to $212^ ext{o}F$ for freezing and boiling points, respectively, resulting in $180$ divisions.
Equivalences:
- A difference of $100^ ext{o}C$ is equivalent to a difference of $180^ ext{o}F$ .
- Therefore, $1^ ext{o}C = rac{180}{100}^ ext{o}F = 1.8^ ext{o}F$
- Also, $1^ ext{o}C$ change is equivalent to $1 K$ change.
Conversion Formulas:
- Celsius to Fahrenheit:
 - $TF = (1.8 imes TC) + 32$
 - Here, $1.8$ has units of $^ ext{o}F / ^ ext{o}C$ , enabling unit cancellation: $TF ext{ (in } ^ ext{o}F ext{)} = rac{1.8 ^ ext{o}F}{1 ^ ext{o}C} imes TC ext{ (in } ^ ext{o}C ext{)} + 32 ^ ext{o}F$
- Fahrenheit to Celsius:
 - $TC = (TF - 32) / 1.8$
- Celsius to Kelvin:
 - $TK = TC + 273.15$ (or typically $273$ for simplicity)

Absolute Zero and the Kelvin Scale

Absolute Zero: The coldest possible temperature, defined as $-273.15^ ext{o}C$ (or approximately $-273^ ext{o}C$ ), which corresponds to $0 K$ .
Kelvin Scale: Starts at absolute zero ( $0 K$ ). It is a direct scale; there are no negative Kelvin temperatures.
Experimental Determination of Absolute Zero: By plotting the volume of a gas against its temperature ($^ ext{o}C $) and extrapolating the line to zero volume, one can estimate the temperature at which volume becomes zero, which corresponds to$ -273^ ext{o}C $.</li></ul><h5 id="03f7d96f-243e-4c9a-8f7a-1565a26dcf74" data-toc-id="03f7d96f-243e-4c9a-8f7a-1565a26dcf74" collapsed="false" seolevelmigrated="true">Problem Solving Steps for Temperature Conversions</h5><ol><li>Plan: Identify what is given, what is needed, and the relationship (formula) to connect them.</li><li>Rearrange: If necessary, rearrange the formula to solve for the needed quantity.</li><li>Substitute: Plug in the known values, ensuring correct units.</li><li>Calculate: Perform the calculation.</li><li>Units and Sig Figs: Always include units and consider significant figures, especially when adding/subtracting (decimal places) and multiplying/dividing (sig figs).<ul><li>Example: Convert$ 21^ ext{o}C $to$ ^ ext{o}F $.<ul><li>$ T_F = (1.8 imes 21) + 32 = 37.8 + 32 = 69.8^ ext{o}F $</li></ul></li><li>Example: Convert$ 37^ ext{o}C $to K.<ul><li>$ T_K = 37 + 273 = 310 K $</li></ul></li></ul></li></ol><h5 id="b7508aad-9d78-42d0-93a0-2dce020756ea" data-toc-id="b7508aad-9d78-42d0-93a0-2dce020756ea" collapsed="false" seolevelmigrated="true">Temperature Comparisons</h5><ul><li>Sun surface temperature:$ 5,500^ ext{o}C $</li><li>Hot oven:$ 200-250^ ext{o}C $</li><li>Water boils:$ 100^ ext{o}C $or$ 373 K $</li><li>High fever:$ 40^ ext{o}C $($ 104^ ext{o}F $)</li><li>Normal body temperature:$ 37^ ext{o}C $($ 98.6^ ext{o}F $) or$ 310 K $</li><li>Room temperature:$ 20-25^ ext{o}C $</li><li>Water freezes:$ 0^ ext{o}C $or$ 273 K $</li><li>Northern winter: Below$ 0^ ext{o}C $</li><li>Nitrogen liquefies:$ -269^ ext{o}C $or$ 4 K$$