Introduction to Matter

Definitions and Properties

Matter is anything that has mass and occupies volume. All substances in the universe are forms of matter.

• Mass: The amount of matter in an object. Measured in grams (g), kilograms (kg), etc.

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

States of Matter

• Solid: Definite shape and volume; particles are closely packed in a fixed arrangement.

• Liquid: Definite volume but no definite shape; particles are close but can move past each other.

• Gas: No definite shape or volume; particles are far apart and move freely.

Composition of Matter

• Element: A pure substance that contains only one type of atom. Examples: copper (Cu), oxygen (O2).

• Compound: A pure substance composed of two or more different types of atoms chemically bonded together. Example: water (H2O).

Properties of Matter

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

• Physical Properties: Can be observed without changing the chemical identity (e.g., color, 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 (e.g., density, boiling point).

Classification of Matter

Pure Substances

• Elements: Contain only one type of atom.

  • Monatomic: Consist of single, unbonded atoms (e.g., He, Ne).

  • Diatomic: Consist of two atoms bonded together (e.g., O2, N2).

  • Polyatomic: Consist of more than two atoms bonded together (e.g., S8).

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

• Compounds: Contain two or more different types of atoms chemically bonded. Properties differ from those of their constituent elements. Examples: NaCl (sodium chloride), H2O (water).

Mixtures

• Homogeneous Mixture (Solution): Uniform composition and properties throughout; particles are evenly mixed. Example: saltwater, air.

• Heterogeneous Mixture: Non-uniform composition; different parts have different properties. Example: salad, sand in water.

• Alloy: A homogeneous mixture of metals (e.g., brass, bronze).

• Suspension: A heterogeneous mixture where particles settle over time (e.g., muddy water).

Classification Chart

Separating Mixtures

Mixtures can be separated by physical means or physical changes:

1. Sorting: Manually separating components based on physical properties.

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

3. Magnet: Uses magnetic properties to separate substances.

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

5. Density: Separation based on differences in density.

6. Distillation: Separates substances based on differences in boiling points.

Density

Density is the mass per unit volume of a substance. It is an intensive property, meaning it does not depend on the amount of substance.

• Formula:

• Typical units: g/cm3 for solids, g/mL for liquids

• Density of water: approximately 1.00 g/mL at 4°C

Density Calculations

• To find mass:

• To find volume:

Example Problems:

1. A sample of lead (Pb) has mass 22.7 g and volume 2.0 cm3. Find the sample's density. Solution:

2. Another sample of lead occupies 16.2 cm3 of space. Find the sample's mass (using density from above). Solution:

Physical and Chemical Properties

• Chemical Properties: How a substance reacts with other substances (e.g., reactivity, flammability).

• Physical Properties: Observed without changing the substance (e.g., color, melting point).

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

• Intensive Properties: Independent of the amount (e.g., density, boiling point).

Examples of Properties

• Electrical conductivity (intensive, physical)

• Reactivity with water (chemical)

• Heat content (extensive, physical)

• Ductile: Can be drawn into wire (physical)

• Malleable: Can be hammered into shape (physical)

• Brittle: Breaks easily (physical)

• Magnetism (physical)

States of Matter and Changes of State

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

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

• Gas: Particles are far apart and move freely.

Changes of State: Melting, freezing, vaporization, condensation, sublimation, deposition.

Energy in Chemistry

Kinetic Energy

Kinetic energy is the energy of motion. In chemistry, it is often associated with the movement of particles.

Law of Conservation of Energy

Energy cannot be created or destroyed, only transformed from one form to another.

Energy Changes

• Endothermic Change: System absorbs heat (e.g., melting, boiling).

• Exothermic Change: System releases heat (e.g., freezing, combustion).

The Mole Concept

Atoms and molecules are counted using the mole (mol), a fundamental unit in chemistry.

• 1 mole = particles (Avogadro's number)

• The mass of 1 mole of an element (in grams) is equal to its atomic mass from the periodic table.

Island Diagram

The island diagram is a visual tool for converting between grams, moles, and number of particles (atoms or molecules):

• Grams ↔ Moles ↔ Particles

• 1 mole = particles

Sample Problems

1. How many moles is atoms of zinc? Solution: mol

2. How many atoms is 0.68 moles of zinc? Solution: atoms

Summary Table: Elements vs. Compounds

Additional Info

• Dehydration of sugar:

• Electrolysis of water:

Additional info: Some context and explanations have been expanded for clarity and completeness, as the original notes were in outline form.