Matter and Its Classification

Introductory Definitions

Matter is anything that has mass and occupies volume. All physical objects are composed of matter.

• Mass: The quantity of matter in an object, typically measured in grams (g) or kilograms (kg).

• Volume: The amount of space an object occupies. Common units include liters (L), cubic decimeters (dm3), milliliters (mL), and cubic centimeters (cm3).

State of matter: Matter exists primarily in three states: solid, liquid, and gas.

Composition: The types of particles (atoms, molecules) that make up a substance. For example, copper is composed of copper atoms, while water is composed of H2O molecules.

Atom: The basic building block of matter, consisting of protons, neutrons, and electrons.

Elements

Elements are pure substances that contain only one type of atom.

• Monatomic elements: Consist of unbonded, "like" atoms (e.g., noble gases such as helium).

• Polyatomic elements: Consist of several "like" atoms bonded together. Diatomic elements include H2, O2, N2, F2, Cl2, Br2, I2.

• Allotropes: Different forms of the same element in the same state of matter (e.g., oxygen: O2 and O3; carbon: diamond, graphite).

Compounds

Compounds are substances that contain two or more different types of atoms chemically bonded together. Their properties differ from those of their constituent elements.

• Examples: NaCl (sodium chloride), H2O (water).

• Atoms can only be altered by chemical means; molecules can be altered by physical means.

Example Equations:

• Dehydration of sugar:

• Electrolysis of water:

Classifying Matter

Matter can be classified as either pure substances or mixtures.

Mixtures

Mixtures are combinations of two or more substances that are not chemically bonded.

• Homogeneous mixtures (solutions): Particles are evenly mixed; composition and properties are uniform throughout (e.g., salt water, air).

• Heterogeneous mixtures: Composition and properties vary within the sample; not evenly mixed (e.g., salad, granite).

• Alloy: A homogeneous mixture of metals (e.g., 24K gold).

• Suspension: A heterogeneous mixture that settles over time (e.g., muddy water).

Chart for Classifying Matter

Separating Mixtures

Mixtures can be separated by physical means or physical changes:

1. Sorting: Separating based on physical characteristics.

2. Filtration: Separating solids from liquids using a filter.

3. Magnet: Using a magnet to separate magnetic materials.

4. Chromatography: Separating substances based on their movement through a medium.

5. Density: Separating based on differences in density.

6. Distillation: Separating based on differences in boiling points.

Density

Density is the mass per unit volume of a substance.

• Formula:

• Typical units: g/cm3 for solids, g/mL for fluids.

• The density of a liquid or solid is nearly constant, regardless of sample size.

• **Density of water = 1.00 g/cm3 at 4°C

Density Calculations:

• Given mass and volume, calculate density using the formula above.

• Given density and volume, calculate mass:

• Given mass and density, calculate volume:

Properties of Matter

• Chemical properties: Describe how a substance reacts with other substances (e.g., reactivity with water).

• Physical properties: Can be observed without changing the chemical identity of the substance (e.g., melting point, density).

• Extensive properties: Depend on the amount of substance present (e.g., mass, volume).

• Intensive properties: Do not depend on the amount of substance present (e.g., density, boiling point).

Examples:

• Electrical conductivity

• Reactivity with water

• Heat content (total energy)

• Ductile: Can be drawn into wire

• Malleable: Can be hammered into shape

• Brittle: Breaks easily

• Magnetism

States of Matter and Changes of State

Matter exists in three primary states: solid, liquid, and gas. Each state has distinct particle arrangements and properties.

• Solid: Particles are closely packed in a fixed arrangement.

• Liquid: Particles are close but can move past each other.

• Gas: Particles are far apart and move freely.

Changes of State: Matter can change from one state to another through physical processes such as melting, freezing, condensation, and evaporation.

Energy and Chemical Change

• Kinetic energy: The energy of motion.

• Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed from one form to another.

Example: Combustion of acetylene:

Energy Changes in Reactions

• Endothermic change: The system absorbs heat (e.g., water boiling, steam condensing).

• Exothermic change: The system releases heat (e.g., water freezing, ice melting).

The Mole Concept

Atoms are extremely small, so chemists use the mole to count them in practical quantities.

• 1 mole of atoms = atoms (Avogadro's number).

• For any element, 1 mole has a mass in grams equal to its atomic mass from the Periodic Table.

Island Diagram for Counting Atoms, Moles, and Mass

Sample Island Diagram Problems

1. How many moles is atoms of zinc?

2. How many atoms is 0.68 moles of zinc?

3. How many grams is 5.69 moles of uranium?

4. How many grams is atoms of neon?

5. How many atoms is 421 g of promethium?

Additional info: Some context and definitions have been expanded for clarity and completeness. All equations are provided in LaTeX format as required.