## Properties of Matter

All matter has properties that help us describe and identify it. Properties fall into two categories:

### Intensive Properties (DO NOT change with amount)

Intensive properties stay the same no matter how much of the substance you have. They are used to identify unknown substances.

- Density - mass per unit volume (d = m/V) - Melting point - temperature at which a solid becomes a liquid - Boiling point - temperature at which a liquid becomes a gas - Solubility - how much solute dissolves in a solvent - Color - the appearance of the substance - Hardness - resistance to scratching

A wooden toothpick and a wooden log have the same density because they are made of the same material. The amount does not matter.

### Extensive Properties (DO change with amount)

Extensive properties depend on how much matter is present.

- Mass - the amount of matter - Volume - the space matter occupies - Weight - the gravitational force on an object - Length - a measure of distance

### Density

Formula: d = m / V

Units: g/mL or g/cm3 (these are equivalent for liquids)

Float/Sink Rule: - Density less than 1.0 g/mL = floats in water - Density greater than 1.0 g/mL = sinks in water

Example calculation: An object has a mass of 24 g and a volume of 8 mL.

d = m / V = 24 g / 8 mL = 3.0 g/mL

Since 3.0 > 1.0, this object sinks in water.

## States of Matter and Phase Changes

### Kinetic Molecular Theory

All matter is made of tiny particles (atoms or molecules) that are in constant motion. Temperature measures the average kinetic energy of the particles. Higher temperature = faster particle motion.

### Three States of Matter

| State | Shape | Volume | Particle Behavior | |-------|-------|--------|-------------------| | Solid | Fixed shape | Fixed volume | Particles vibrate in fixed positions | | Liquid | Takes container shape | Fixed volume | Particles slide past each other | | Gas | Fills entire container | Fills entire container | Particles move freely and rapidly |

### Six Phase Changes

Energy ADDED (particles speed up): - Melting - solid to liquid - Evaporation/Boiling - liquid to gas - Sublimation - solid directly to gas

Energy REMOVED (particles slow down): - Freezing - liquid to solid - Condensation - gas to liquid - Deposition - gas directly to solid

### What Happens During a Phase Change?

During a phase change, the temperature stays CONSTANT. This appears as a flat horizontal line on a heating curve. The energy being added (or removed) goes into breaking or forming bonds between particles, not into raising or lowering the temperature.

### Heating Curve (from solid to gas)

1. Temperature rises as solid warms up 2. Temperature plateaus at the melting point (solid melts to liquid) 3. Temperature rises as liquid warms up 4. Temperature plateaus at the boiling point (liquid boils to gas) 5. Temperature rises as gas warms up

## Energy Transfer

Thermal energy always flows from WARMER objects to COOLER objects until both reach the same temperature. This is called thermal equilibrium.

### Three Methods of Heat Transfer

| Method | How It Works | Where It Works | Example | |--------|-------------|----------------|--------| | Conduction | Direct contact between particles. Particles collide and transfer energy. | Best in solids, especially metals | Touching a hot stove burns your hand | | Convection | Fluid circulation. Warm fluid rises, cool fluid sinks, creating currents. | Liquids and gases only | A pot of boiling water circulates | | Radiation | Electromagnetic waves. No particles or medium needed. | Works through empty space | The Sun heats the Earth across space |

### Key Details

- Conduction works best in metals because their particles are tightly packed and electrons move freely. - Convection creates currents: warm fluid rises (less dense), cool fluid sinks (more dense), and the cycle repeats. - Radiation is the only method that works through empty space (vacuum). This is how the Sun's heat reaches Earth.

### Conductors vs. Insulators

- Conductors transfer heat easily: copper, aluminum, iron, steel, and other metals - Insulators resist heat flow: wood, plastic, rubber, air, wool, foam, glass

Conductors are used in cooking pans to transfer heat quickly. Insulators are used in oven mitts and winter coats to slow heat transfer.

## Logical Fallacies Quick Reference

A logical fallacy is an error in reasoning that weakens an argument. Learn to recognize these 8 common fallacies:

| Fallacy | What It Does | Example | |---------|-------------|---------| | Ad Hominem | Attacks the person, not the argument | "You failed math, so your opinion on the budget is worthless." | | Straw Man | Distorts the argument into an extreme version | "You want less homework? So you want students to never learn anything?" | | Red Herring | Changes the subject to distract | "Why worry about pollution when there are potholes on the roads?" | | Bandwagon | Claims something is true because everyone does it | "Everyone is buying this phone, so it must be the best." | | False Dilemma | Presents only two options when more exist | "Either you agree with me, or you don't care about the environment." | | Slippery Slope | Claims one step leads to disaster without evidence | "If we allow phones in class, students will never read books again." | | Appeal to Authority | Uses a famous person without relevant expertise | "This celebrity says the product works, so it must." | | Circular Reasoning | Uses the conclusion as its own evidence | "This is the best school because no school is better." |