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...* Left : When salt
water dried up in experiment 11 crystals were
formed looking like cubes. These crystals of pure salt are
made of the smallest
invisible particles called sodium particles and
chloride
particles.
So table salt is
called sodium chloride by chemists.
* Photo 2: Yellow
beads are models for positive sodium particles, green beads are models
for negative chloride particles.
Sodium particles repel each other. So do chloride particles because they
have like charges (+ und -).
* Photo 3:
When positive charged particles and negative ones are close together, the
4 particles attract each other.
* Right: Make
such a cube model of sodium chloride by connecting 8 beads using brass
wire.
4 sodium particles (Na+) and 4 chloride particles
(Cl-) form the smallest possible cube.