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Chemistry
Yr 7
Topic 2 - Atoms, elements and molecules
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Anna van der Velden
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Atoms
on a picture look like
single circles
Molecules of a compound on a picture look like two
small
circles
stuck together or a small
circle
Molecules of a mixture is just
molecules
but
different
kinds of
molecules
in the picture
Molecules of a compound look like a
big ball
and then
two small circles
Periodic table:
118
elements
Everything is made up of
atoms
Mixture:
2+
elements
not
joined
together
Element:
simple substances
made of only
one
kind of
atom
Compound:
1+ element
joined together
Molecule
: A group of
atoms
bonded together
Metals obtained from compounds are
minerals
Metals have a
high
melting point, are
malleable
and ductile,
shiny
, good
conductors
of heat and electricity.
Copper
,
zinc
and
iron
are metals
Non-metals:
low
melting point,
brittle
, not
shiny
, good
insulators
of heat and electricity.
Sulphur
,
oxygen
,
iodine
and
carbon
are non-metals
Zinc + oxygen -->?
Zinc
oxide
Sodium + carbon -->?
Sodium carbonate
Chemical reactions always form
1+
new substances
Physical reactions form
no new substances
Heat
is often needed to start a chemical reaction
Signs of a chemical reaction:
colour
change,
gas
being given off, an
energy
change and a
solid
forming in a
liquid.