Topic 1 - Matter and Energy - Revsworld

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Topic 4 - Chemical bonding
32. Lewis electron-dot diagrams: Lewis diagrams for common molecular substances
Concept Task : Be able to draw, show, or recognize Lewis electron-diagrams for molecular substances.
Below, you will see examples Lewis electron-dot diagrams for some common molecular substances.
Polar substances (note how these diagrams have asymmetrical shapes)
Molecular name Molecular formula Lewis electron-dot diagrams
Hydrogen chloride HCl H. x Cl x or H – Cl x
.
Water H 2 O .O. . . . . . . .
O
/ \
H x x H or H H
Ammonia NH 3 H. x N x . H or H – N – H
x
.
H
H
Nonpolar substances (note how these diagrams have symmetrical shapes)
Molecular name Molecular formula Lewis electron-dot diagrams
. . x x
Chlorine Cl 2 : Cl .
x
. . x x
x
x Cl or : Cl – Cl x
x x x
x x
x x
x x x
x x
x x
. . x x x . . x x
. .
Carbon dioxide CO 2 O : C : . O . . or O . x x
= C = O
. .
. .
x x
. . . . . .
Methane CH 4 H H
Carbon tetrachloride CCl 4
H . x C x . H or H – C – H
x
.
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x
H
H
.. ..
: Cl . : : Cl :
. . . x . . . . . .
: Cl . x C x . Cl : or : Cl – C – Cl :
.
: Cl : : Cl :
.. . . x . . . . . .
. . . .