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User guide
Teachers’ Guide
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Substances
A1 Melting/Freezing
B1 The particle theory
C1 The gas state
D1 The three states
E1 Density
Mixtures
F1 Melting behaviour
G1 Evaporation of water
H1 Condensation of water
I1 Recognising dissolving
J1 Solubility
K1 Separating mixtures
Changing substances
L1 Structures
M1 Chemical change
Advanced substances
N1 Crystals
O1 Change of state
P1 Gas and pressure
Advanced mixtures
Q1 Diffusion
R1 Rate of evaporation
S1 Rate of dissolving
T1 Chromatography
Advanced changes
U1 Formulae
V1 Fire
W1 Acids
L1.2 TWO DIFFERENT STRUCTURES
LINKS
Ice and salt illustrate two different possible structures:
The atoms are bonded in groups, called
molecules
.
Water has a
molecular structure
: atoms are only bonded to other atoms in the same molecule.
Notes: see Teachers’ Guide
It is not possible to pick out particular groups: there are
no
molecules.
Salt has a
giant structure
: each atom is bonded
to all of its neighbours.
teachers’ guide l1
more info
l1: atoms
l2: atom structures
l3: giant structures
l4: other structures
l5: using ideas
more info
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a Science Enhancement Programme CD-ROM 2005
user guide
