Elements and Mixtures

Elements

• A substance that consists of only one type of atom
• Cannot be broken down into simpler substances by chemical means
• 118 known elements, each with a unique atomic number (number of protons in the nucleus)
• Examples: hydrogen (H), carbon (C), oxygen (O)

Mixtures

• A physical blend of two or more substances, where each substance maintains its chemical properties
• Can be separated into individual components by physical means (e.g., filtration, sedimentation)
• Properties of a mixture vary depending on the proportion of each component
• Examples: air (oxygen, nitrogen, carbon dioxide), soil (sand, silt, clay)

Compounds

• A substance formed by the chemical combination of two or more different elements
• Have unique properties different from the individual elements
• Can be broken down into simpler substances by chemical means
• Examples: water (H2O), carbon dioxide (CO2), sodium chloride (NaCl)

Pure Substances

• A substance that has a fixed composition and properties
• Can be either an element or a compound
• Has a unique set of physical and chemical properties
• Examples: pure water, pure sodium chloride (table salt)

Separation Techniques

Physical Separation Techniques

• Filtration: separating a mixture based on differences in particle size
• Sedimentation: separating a mixture based on differences in density
• Decantation: separating a mixture based on differences in density
• Crystallization: separating a mixture based on differences in solubility

Chemical Separation Techniques

• Distillation: separating a mixture based on differences in boiling points
• Chromatography: separating a mixture based on differences in affinity for a stationary phase
• Electrolysis: separating a mixture based on differences in electrical conductivity

Elements

• Consist of only one type of atom
• Cannot be broken down into simpler substances by chemical means
• 118 known elements, each with a unique atomic number (number of protons in the nucleus)
• Examples: hydrogen (H), carbon (C), oxygen (O)

Mixtures

• A physical blend of two or more substances, where each substance maintains its chemical properties
• Can be separated into individual components by physical means (e.g., filtration, sedimentation)
• Properties of a mixture vary depending on the proportion of each component
• Examples: air (oxygen, nitrogen, carbon dioxide), soil (sand, silt, clay)

Compounds

• Formed by the chemical combination of two or more different elements
• Have unique properties different from the individual elements
• Can be broken down into simpler substances by chemical means
• Examples: water (H2O), carbon dioxide (CO2), sodium chloride (NaCl)

Pure Substances

• Have a fixed composition and properties
• Can be either an element or a compound
• Have a unique set of physical and chemical properties
• Examples: pure water, pure sodium chloride (table salt)

Separation Techniques

Physical Separation Techniques

• Filtration: separates a mixture based on differences in particle size
• Sedimentation: separates a mixture based on differences in density
• Decantation: separates a mixture based on differences in density
• Crystallization: separates a mixture based on differences in solubility

Chemical Separation Techniques

• Distillation: separates a mixture based on differences in boiling points
• Chromatography: separates a mixture based on differences in affinity for a stationary phase
• Electrolysis: separates a mixture based on differences in electrical conductivity