Chemistry and Matter

Definition and Classification of Matter

Chemistry is the study of matter and the changes it undergoes, with the atom being its basic functional unit. 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 but not chemically bonded.

Classification of Matter Table

Example: Crystalline sugar and lead wire are pure substances; salsa is a heterogeneous mixture; Gatorade is a homogeneous mixture.

Mixtures: Homogeneous vs. Heterogeneous

• Homogeneous Mixture: Uniform composition throughout (e.g., seawater, black coffee).

• Heterogeneous Mixture: Non-uniform composition (e.g., chicken noodle soup, trail mix).

Practice: Classify substances such as ammonia (compound), gold bar (element), orange juice (mixture), wine (mixture), saline solution (mixture).

Physical and Chemical Changes

Physical Changes

Physical changes are changes in the physical state of a substance without a change in composition. Examples include dissolving, melting, boiling, and freezing.

• Physical Change: Change of state, solubility, melting, boiling, freezing, etc.

Example: Dissolving sugar in water is a physical change; wood burning is not.

Chemical Changes

Chemical changes involve changes in chemical composition that create new chemical bonds and products. Examples include rusting, combustion, and reactions that produce new substances.

• Chemical Change: Change of metals, food, material, reactions, etc.

Example: Cooking an egg is a chemical change; melting wax is not.

Reversible and Irreversible Changes

Reversible Changes

Reversible changes can be undone to restore the original structure of a compound. Phase changes and dissolving are common examples.

• Phase Change: Transition between solid, liquid, and gas states (e.g., melting, freezing).

Irreversible Changes

Irreversible changes are permanent and cannot be undone to restore the original structure. Chemical reactions are typical examples.

• Example:

Chemical and Physical Properties

Chemical Properties

Chemical properties are observed during a chemical reaction and describe how a substance transforms into a new substance.

• Example: Flammability, reactivity with acids, oxidation.

Physical Properties

Physical properties can be measured or observed without changing the chemical structure of a substance.

• Example: Density, color, melting point, boiling point, state of matter.

Intensive and Extensive Properties

Intensive Properties

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

• Examples: Melting point, density, temperature, luster.

Extensive Properties

Extensive properties depend on the size or amount of substance present.

• Examples: Mass, volume, energy, moles.

Temperature and Heat

Thermal Energy, Temperature, and Heat

Thermal energy is the sum of the kinetic and potential energies of all atoms in an object. Temperature is the average kinetic energy of the particles, while heat is the flow of thermal energy from a higher temperature object to a lower temperature object.

• Temperature: Measured in degrees Celsius (), Fahrenheit (), or Kelvin (K).

• Heat: Energy transfer due to temperature difference.

Temperature Conversions

Scientific Notation

Format for Scientific Notation

Scientific notation is used to express very large or small numbers in a compact form: .

• Coefficient: Number between 1 and 10.

• Exponent: Integer indicating the power of ten.

• Base: Always 10.

Standard Notation to Scientific Notation

• Move the decimal point to create a coefficient between 1 and 10.

• Count the number of places moved to determine the exponent.

SI Base Units and Measurements

SI Base Units

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

Perimeter, Area, and Volume

• Perimeter: Total length around an object.

• Area: Measure of surface.

• Volume: Space occupied by a 3D object.

Example: Calculate the area and volume using SI units for laboratory measurements.

Additional info: These notes cover foundational concepts in physical science relevant to introductory college-level physics and chemistry, including matter classification, properties, changes, measurement, and scientific notation.