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CIE iGCSE Co-ordinated Sciences-Link - Study Notes- New Syllabus

CIE iGCSE Co-ordinated Sciences-C2.1 Elements, compounds and mixtures – Study Notes

CIE iGCSE Co-ordinated Sciences-C2.1 Elements, compounds and mixtures – Study Notes -CIE iGCSE Co-ordinated Sciences – per latest Syllabus.

Key Concepts:

CIE iGCSE Co-Ordinated Sciences-Concise Summary Notes- All Topics

Elements, compounds and mixtures

Elements:

  • Pure substances made of only one type of atom.
  • Cannot be broken down into simpler substances by chemical means.

Compounds:

  • Pure substances made from two or more different elements chemically bonded in a fixed ratio.
  • Can only be separated into elements by chemical reactions.
  •  

Mixtures:

  • Contain two or more substances physically combined, not chemically bonded.
  • Components can be separated by physical methods such as filtration, distillation, or chromatography.
PropertyElementCompoundMixture
CompositionOnly one kind of atomTwo or more elements in a fixed ratioTwo or more substances; ratio not fixed
SeparationCannot be separated chemicallySeparated into elements by chemical reactionSeparated physically
Chemical bondingNo chemical bondsAtoms chemically bondedNo chemical bonds between components
PropertiesUniform and characteristic of elementDifferent from the elements it containsCombination of properties of components
Examples\( \text{H}_2 \), \( \text{O}_2 \), \( \text{Au} \)\( \text{H}_2\text{O} \), \( \text{CO}_2 \), \( \text{NaCl} \)Air, saltwater, sand + iron filings

Example

Classify the following substances as elements, compounds, or mixtures: oxygen gas, water, saltwater, gold, carbon dioxide.

▶️ Answer/Explanation

Oxygen gas (\( \text{O}_2 \)) – Element: contains only one type of atom.

Water (\( \text{H}_2\text{O} \)) – Compound: made of hydrogen and oxygen chemically bonded in a fixed ratio.

Saltwater – Mixture: contains water and dissolved salt physically combined; can be separated by evaporation.

Gold (\( \text{Au} \)) – Element: contains only gold atoms.

Carbon dioxide (\( \text{CO}_2 \)) – Compound: made of carbon and oxygen chemically bonded.

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