Classification of Matter

Types of Matter

Matter is anything that occupies space and has mass. Chemistry is the study of matter and the changes it undergoes, with the atom being its basic functional unit. 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.

Example: Gold bar is an element, ammonia (NH3) is a compound, and orange juice is a mixture.

Physical and Chemical Changes

Physical Changes

Physical changes alter the physical state of a substance without changing its composition. Examples include melting, boiling, dissolving, and tearing.

• Reversible physical changes: Phase changes (solid to liquid, liquid to gas), dissolving compounds in liquids.

Chemical Changes

Chemical changes result in the formation of new chemical bonds and products, changing the chemical composition of the substance. Examples include burning, rusting, and cooking.

• Irreversible chemical changes: Most chemical reactions, such as baking a cake or burning wood.

Example: Dissolving sugar in water is a physical change; cooking an egg is a chemical change.

Chemical and Physical Properties

Chemical Properties

Chemical properties are observed during a chemical reaction and result in the formation of a new substance.

• Examples: Reactivity with oxygen, flammability, toxicity, radioactivity.

Physical Properties

Physical properties are measurable and describe the state of a chemical compound. They can be observed without changing the chemical structure.

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

Intensive vs. Extensive Properties

Intensive Properties

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

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

Extensive Properties

Extensive properties depend on the size or amount of substance present. They are additive for the total amount of material.

• Examples: Mass, volume, length, total energy.

Temperature and Heat

Temperature vs. Heat

Thermal energy is the sum of the kinetic and potential energies of all atoms in an object. Temperature is the average kinetic energy, while heat is the flow of thermal energy from a hotter object to a cooler one.

• Temperature units: Celsius (ºC), Fahrenheit (ºF), Kelvin (K).

Scientific Notation and Significant Figures

Scientific Notation

Scientific notation is used to express very large or very small numbers in a manageable form: where and is an integer.

• Standard notation: The normal way of writing numbers.

• Conversion: Move the decimal point to create a coefficient between 1 and 10, adjusting the exponent accordingly.

Significant Figures

Significant figures are the digits that contribute to the precision of a measurement. More significant figures indicate greater precision.

• Rules: Non-zero digits are significant; zeros between significant digits are significant; leading zeros are not significant; trailing zeros in decimals are significant.

SI Units and Metric Prefixes

SI Base Units

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

Metric Prefixes

Metric prefixes are modifiers that are multiples of ten and are used to express units at different scales (e.g., kilo-, centi-, milli-).

• Examples: 1 kilometer (km) = 1,000 meters (m); 1 milligram (mg) = 0.001 grams (g).

Measurement: Perimeter, Area, and Volume

Definitions and Formulas

• Perimeter: Distance around an object.

• Area: Measured surface of an object.

• Volume: Space occupied by a 3D object.

Dimensional Analysis and Conversion Factors

Dimensional Analysis

Dimensional analysis is a systematic method for converting one unit to another using conversion factors. The process involves starting with the given amount and using conversion factors to reach the desired unit.

• Example: To convert inches to centimeters, use the conversion factor 1 inch = 2.54 cm.

Density

Definition and Formula

Density is the amount of mass per unit volume. It is a physical property that helps identify substances.

• Formula:

• Units: For solids and liquids: g/cm3 or kg/L; for gases: g/L or kg/m3.

Density of Geometric Objects

For geometric objects, density can be calculated using their mass and volume. The volume formulas for common shapes are:

• Cube:

• Sphere:

• Cylinder:

Density of Non-Geometric Objects: Water Displacement

Water displacement is used to determine the volume of irregularly shaped objects. The volume displaced equals the volume of the object.

• Example: If the water level rises from 200 mL to 260 mL when an object is submerged, the object's volume is 60 mL.

Summary Table: Properties of Matter