Compounds Mixtures and Elements Flashcards
What is a pure substance?
A pure substance contains only one type of element or compound.
Key Property: Always has consistent physical and chemical properties under the same conditions. Examples: Oxygen (O₂), Water (H₂O), Gold (Au).
List some physical properties.
Melting point, Boiling point, Electrical & thermal conductivity, Density, Solubility.
List some chemical properties.
Reactivity, Stability, Toxicity, Flammability.
What are elements?
A pure substance made of only one type of atom.
Key Properties: Cannot be broken down into simpler substances. Has unique physical & chemical properties. Classified as metals, nonmetals, or metalloids. Example: Copper (Cu), Oxygen (O₂), Gold (Au).
What are characteristics about metals, nonmetals, and metalloids?
Metals: shiny, good conductors, malleable and ductile. Ex: gold, silver, copper.
Nonmetals: Dull (no shine), poor conductors, most are gases. Ex: hydrogen, oxygen, helium.
Metalloids: Characteristics of metals and nonmetals, semiconductors. Ex: silicon, germanium.
What’s a compound?
Pure substance composed of two or more different elements joined by chemical bonds.
ALWAYS SAME RATIO - E.G. CO2, CHEMICAL FORMULA - CO2, CAN ONLY BE SEPARATED CHEMICALLY NOT PHYSICALLY - CHANGES COMPOSITION.
What are mixtures?
A combination of two or more pure substances NOT chemically combined.
Key Properties: Held together by physical forces (not chemical bonds). No chemical change occurs. Each substance keeps its own properties. Can be separated by physical methods (e.g., filtration, distillation). Example: Sand & water, saltwater, air.
Key information about compounds and mixtures.
Mixtures have a variable composition, while compounds have a fixed composition. Mixtures are not chemically bonded and retain their original properties. Compounds are chemically bonded and have new properties. Mixtures can be separated physically, but compounds require chemical separation.
What’s a homogeneous mixture?
Homogeneous Mixture → Evenly mixed; looks the same throughout.
NOTE- YOU CANT SEE BUBBLES- E.G. gas fully dissolve like soft drinks so heterogenous
Example: Saltwater, air, alloys (brass).
Example: Saltwater, air, alloys (brass).
What’s a heterogeneous mixture?
Heterogeneous Mixture → Unevenly mixed; different parts are visible.
NOTE- YOU CAN SEE BUBBLES- E.G. gas doesnt fully dissolve like soft drinks so heterogenous
Example: Salad, sand in water, oil & water.
Example: Salad, sand in water, oil & water.
List the 4 physical separating techniques for mixtures.
Techniques include: Gravity filtration, Distillation, Separatory funnel/decanting, Magnetism.
What is gravity filtration?
Uses filter paper to catch solid particles while liquid passes through.
Example: Separating sand from water.
What is distillation?
Separates liquids by boiling point.
Example: Separating alcohol from water.
What is Separatory Funnel/Decanting?
Separatory funnel/decanting works by density differences.
✔ Denser (heavier) liquids sink to the bottom, while less dense (lighter) liquids float on top.
✔ The bottom liquid is drained first, leaving the top liquid behind.
💡 Example: Oil & Water
Example: Oil & Water.
What is the separating technique of magnetism?
Separates magnetic materials from non-magnetic ones
A magnet pulls out magnetic substances.
Example: Removing iron filings from sand.
Example: Removing iron filings from sand.
What is Electrolysis?
(ASK IF U NEED TO KNOW MORE CHEMICAL)
✔ Definition: Electrolysis uses electricity to chemically break down a compound into its elements.
✔ Process: Electric current forces oxidation & reduction reactions.
✔ Example: Splitting NaCl → Na + Cl₂.
✔ Type of Change: Chemical change (bonds are broken).
When to Use Electrolysis?
✔ Used for ionic compounds (like salts or metal oxides).
✔ Required when physical methods (filtration, distillation) won’t work.
✔ Common for metal extraction, water splitting, and chlorine production.
