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Metals
and non-metals
Francine
Taylor-Campbell, Contributor
IMPORTANT
POINTS
- Metals
are generally found in groups one,
two and three of the periodic table.
- The
term metal describes an element
that ionises by losing electrons
and is referred to as being electropositive.
- Metals
are reducing agents.
- Most
metals react with dilute acids,
water and steam.
- The
oxides of metals are basic (except
for Al, Zn and Pb) and react with
acids to form salt and water.
- Metals
exhibit the following physical properties:
high melting and boiling points,
good electrical and thermal conductivity,
solids at room temperature (except
for Hg) and easily bent or drawn
into wires.
- The
bonding in metals is responsible
for their physical properties.
As
stated earlier, metals undergo reactions
with acids, oxygen, water and steam.
The ease with which these reactions
occur is dependent on the position
of the metal in the reactivity series.
The following is a list of metals
arranged in order of their reactivity
or how readily they will lose their
outer electrons. A metal that will
readily give up its electrons (for
example K) is more reactive than
one that loses electrons less readily
(for example Cu). Metals at the
top of the series are the most electropositive
and the ones at the bottom are the
least electropositive.
The
reactivity series of metals
| K |
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
V
|
Most
reactive |
| Na |
|
|
| Ca |
Decreasing
reactivity, ease of ionisation,
stability of compounds and strength
as reducing agents.
Least reactive
|
| Mg |
| Mg |
| Al |
| Fe |
| Pb |
| (H) |
| Cu |
| Hg |
| Ag |
| Au |
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Summary
of the reactions of metals
1.
Metals react with air or oxygen to
form oxides
2Ca
+ O2 == 2CaO calcium oxide
Ag
and Au have no reaction with oxygen.
2.
Metals react with water or steam to
form the oxide or hydroxide.
Na,
K and Ca react with cold water to
form the hydroxide and hydrogen.
2Na
+ 2H2O (l) == 2NaOH + H2
Metals
above Pb react with steam to produce
the oxide and hydrogen.
Mg
+ H2O (g) == MgO + H2
Below
this, there is no reaction with water
or steam
3.
With dilute acids, the metals higher
up in the series react violently,
forming salt and hydrogen. As you
go down the list, the reaction is
less vigorous until you reach Pb,
Cu, Ag and Au, which have no reaction.
4.
The thermal stability of the nitrates,
carbonates and hydroxides of metals
is also based on the reactivity series.
The ease with which these compounds
decompose when heated increases as
you go down the series.
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Valedictorian
Kristy Ann Ramkisoon after receiving
her Bachelor of Science degree
with first-class honours, at
the University West Indies presentation
of graduates, at the Mona campus,
on Saturday, November 8.
- Peta-Gaye Clachar/Staff Photographer
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Francine
Taylor-Campbell is an independent
contributor.
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