BRAINCAKEEvidence for the Existence of Ions
Evidence for ions is electrolysis. If a direct current is passed through green copper(II) chromate (VI) solution the blue Cu2+ cations migrate to the cathode and the yellow negative CrO42- anion goes to the anode.
Migration of ions
A strip of filter paper on a microscope slide is soaked in a colourless electrolyte and a drop of copper(II) chromate(VI) solution is placed in the centre. The ends are connected to a d.c. supply. After some time a blue colour moves towards the negative electrode and a yellow colour moves towards the positive electrode.
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Key terms in this lesson
- cation
- A positively charged ion, formed when an atom loses one or more electrons.
- anion
- A negatively charged ion, formed when an atom gains one or more electrons.
More in Bonding
- The Strength of Ionic Bonds
- Trends in Ionic Radii
- Physical Properties of Ionic Compounds
- Formation of Ions
- Covalent Bonds
- π-bonds
- Bond Length and Bond Strength
- Electronegativity
All 15 lessons in Bonding · All Edexcel AS-level Chemistry topics