Elements, Compounds, And Mixtures Flashcards
(25 cards)
What is an element?
A pure substance made of only one type of atom.
Example: Oxygen (O), Gold (Au)
How many elements are there in the periodic table?
Over 100 known elements.
What is a compound?
A substance made from two or more elements chemically bonded together.
Example: Water (H₂O), Carbon dioxide (CO₂)
What is a mixture?
A combination of substances not chemically bonded.
Example: Air, saltwater.
What is the difference between a compound and a mixture?
Compounds have chemically bonded atoms; mixtures do not.
Can mixtures be separated easily?
Yes, by physical methods like filtration, evaporation, or distillation.
Can compounds be separated easily?
No, they require chemical reactions to separate.
What are the properties of compounds like?
Different from the elements they are made of.
Example: Sodium (explosive) + chlorine (toxic gas) = sodium chloride (table salt).
What are the properties of mixtures like?
A combination of the properties of the substances within.
What is a molecule?
Two or more atoms bonded together.
Example: O₂ (oxygen molecule), H₂O (water)
What is a chemical formula?
A representation of a compound showing the elements and number of atoms.
Example: CO₂ has 1 carbon and 2 oxygen atoms.
What is a symbol equation?
A chemical equation using symbols and formulas to show reactions.
Example: 2H_2 + O_2 \rightarrow 2H_2O
What is the difference between a compound and a molecule?
All compounds are molecules, but not all molecules are compounds (e.g., O₂ is a molecule, not a compound).
What is a homogeneous mixture?
A mixture with uniform composition throughout.
Example: Salt dissolved in water.
What is a heterogeneous mixture?
A mixture with visibly different substances or phases.
Example: Sand and iron filings.
What is filtration used for?
To separate an insoluble solid from a liquid.
What is distillation used for?
To separate a liquid from a solution by boiling and condensing.
What is crystallisation?
Separating a dissolved solid from a liquid by forming crystals as the solution cools.
What is chromatography?
A technique to separate and identify substances in a mixture (especially inks/dyes).
What is a solute?
A substance that dissolves in a solvent.
What is a solvent?
The liquid that dissolves the solute.
Example: Water is a solvent in saltwater.
What is a solution?
A mixture formed when a solute dissolves in a solvent.
What is an alloy?
A mixture of a metal with other elements.
Example: Steel (iron + carbon)
Why are alloys used instead of pure metals?
Alloys are usually stronger, harder, or more resistant to corrosion.
