Matter, Elements, and Compounds

• Matter is anything that has mass and takes up space
• Matter can be classified based on its composition and properties

Pure Substances

• Pure substances have a fixed composition and distinct properties
• They can be either elements or compounds

Elements

• Elements are the simplest form of matter and cannot be broken down into simpler substances by chemical means
• Each element is composed of only one type of atom
• Examples include gold (Au), oxygen (O), and nitrogen (N)

Compounds

• Compounds are substances composed of two or more different elements chemically bonded together in a fixed ratio
• Compounds can be broken down into simpler substances by chemical means
• The properties of a compound are different from those of its constituent elements
• Examples include water (H2O), carbon dioxide (CO2), and sodium chloride (NaCl)

Mixtures

• Mixtures are combinations of two or more substances that are physically combined
• The composition of a mixture can vary
• Mixtures can be classified as homogeneous or heterogeneous

Homogeneous Mixtures

• Homogeneous mixtures have a uniform composition throughout
• The different components are evenly distributed and not easily visible
• Also known as solutions
• Examples include salt water, sugar dissolved in water, and air

Heterogeneous Mixtures

• Heterogeneous mixtures have a non-uniform composition
• The different components are visible and easily distinguishable
• Examples include sand and water, oil and water, and salad

Solutions

• Solutions are homogeneous mixtures in which one substance (the solute) is dissolved in another substance (the solvent)
• The solute is the substance that is dissolved, and the solvent is the substance that does the dissolving
• Solutions can be solid, liquid, or gas

Solute

• The solute is the substance that is dissolved in a solvent to form a solution
• Solutes can be solid, liquid, or gas

Solvent

• The solvent is the substance that dissolves the solute to form a solution
• The solvent is usually a liquid, but can also be a solid or a gas

Mechanical Mixtures

• Mechanical mixtures (also known as heterogeneous mixtures) are mixtures in which the different components are easily visible and can be separated by physical means
• The composition is not uniform
• Examples include gravel, mixed nuts, and a pizza

Alloys

• Alloys are homogeneous mixtures of two or more metals, or a metal and a non-metal
• They are created to enhance certain properties of the base metal, such as strength, hardness, or corrosion resistance
• Examples include brass (copper and zinc), steel (iron and carbon), and bronze (copper and tin)

Soluble and Insoluble

• Soluble refers to a substance that can dissolve in a solvent
• Insoluble refers to a substance that cannot dissolve in a solvent

Factors Affecting Solubility

• Temperature: Solubility of solids usually increases with temperature, while solubility of gases usually decreases with temperature
• Pressure: Pressure has little effect on the solubility of solids and liquids, but it significantly affects the solubility of gases (Henry's Law)
• Nature of Solute and Solvent: "Like dissolves like" - polar solutes dissolve in polar solvents, and non-polar solutes dissolve in non-polar solvents