Classification of Matter

Types of Matter

Chemistry is the study of matter and the changes it undergoes. Matter is anything that occupies space and has mass. Matter can be classified into three main types:

• Element: The simplest type of matter, composed of one kind of atom.

• Compound: Matter composed of two or more different elements that are chemically bonded together.

• Mixture: Matter composed of elements and/or compounds that are physically mixed together, not chemically bonded.

Examples: Gold bar (element), ammonia (compound), orange juice (mixture).

Key Point: Compounds can only be separated into simpler substances by chemical means, while mixtures can be separated by physical means.

Homogeneous vs. Heterogeneous Mixtures

Mixtures can be further classified as:

• Homogeneous Mixture: Uniform composition throughout (e.g., saline solution, coffee).

• Heterogeneous Mixture: Non-uniform composition (e.g., trail mix, fruit salad).

Physical and Chemical Changes

Physical Changes

Physical changes alter the state or appearance of matter without changing its composition. Examples include melting, freezing, dissolving, and tearing.

• Example: Dissolving sugar in water is a physical change.

Chemical Changes

Chemical changes result in the formation of new substances with different properties. Examples include burning, rusting, and cooking an egg.

• Example: Cooking an egg is a chemical change.

Reversible vs. Irreversible Changes

• Reversible Change: Can be undone (e.g., melting and re-solidifying chocolate).

• Irreversible Change: Cannot be undone (e.g., baking a cake).

SI Units and Measurements

SI Base Units

The International System of Units (SI) is based on seven base units:

Perimeter, Area, and Volume

• Perimeter: Distance around an object. Formula:

• Area: Measured surface of an object. Formula:

• Volume: Space occupied by a 3D object. Formula:

Metric Prefixes

Metric Prefix Multipliers

Metric prefixes are modifiers that are multiples of ten. They are used to express very large or very small quantities conveniently.

Significant Figures

Rules for Significant Figures

• Non-zero digits are always significant.

• Any zeros between significant digits are significant.

• Leading zeros are not significant.

• Trailing zeros in the decimal portion are significant.

• Trailing zeros in a whole number with a decimal point are significant.

• Exact numbers have an infinite number of significant figures.

Significant Figures in Calculations

• Multiplication/Division: The result should have as many significant figures as the value with the fewest significant figures.

• Addition/Subtraction: The result should have as many decimal places as the value with the fewest decimal places.

Precision in Measurements

When recording measurements, include all known digits plus one estimated digit.

Temperature

Temperature vs. Heat

• Temperature: The average kinetic energy of particles in a substance.

• Heat: The transfer of thermal energy from a hotter object to a cooler one.

Temperature Conversions

• Celsius to Kelvin:

• Celsius to Fahrenheit:

Scientific Notation

Format and Use

• Scientific Notation: , where is the coefficient (1 ≤ N < 10), and is an integer exponent.

• Positive exponent: Move decimal to the right (large numbers).

• Negative exponent: Move decimal to the left (small numbers).

Chemical and Physical Properties

Chemical Properties

Chemical properties describe how a substance reacts with other substances, resulting in a change in composition.

• Examples: Reactivity with oxygen, flammability, acidity/basicity.

Physical Properties

Physical properties can be observed or measured without changing the substance's chemical identity.

• Examples: Color, density, melting point, boiling point, luster.

Intensive vs. Extensive Properties

Intensive Properties

Intensive properties do not depend on the amount of substance present. They are characteristic properties of the material.

• Examples: Density, melting point, color, luster.

Extensive Properties

Extensive properties depend on the amount of substance present. They are additive for the same material.

• Examples: Mass, volume, length, energy.

Conversion Factors and Dimensional Analysis

Conversion Factors

A conversion factor is a ratio that expresses how many of one unit are equal to another unit. They are used to convert between units in calculations.

• Example:

• Example:

Dimensional Analysis

Dimensional analysis is a systematic approach to problem solving that uses conversion factors to move from one unit to another.

• General format:

Density

Definition and Formula

Density is the amount of mass per unit volume. It is an intensive property.

• Formula:

Units

• Solids/Liquids: or

• Gases:

Density of Geometric Objects

• Cube:

• Sphere:

• Cylinder:

Density of Non-Geometric Objects: Water Displacement

Water displacement is used to determine the volume of irregularly shaped objects by measuring the change in water level when the object is submerged.