The Periodic table Chemistry Grade 10 CAPS

NOtes on the periodic table

1. Elements are arranged according to their
increasing atomic number and atomic mass
in the Periodic Table.
Elements with similar properties are arranged
in vertical & horizontal groups or families.
Vertical columns are called Groups
Horizontal rows are called Periods
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2. Periodic means ‘recurring at regular intervals’.
Periodic Table means that the atoms are arranged in
the table in a manner that recurs regularly.
This refers to the outer energy level electron
structure of each of the elements in a particular
Group.
Group 1 elements all have 1ē in the outer energy
level.
Group 2 have 2ē , Group 3 have 3ē , Group 4 have 4ē
etc.
This means that the elements in a particular Group
will all have similar properties – same ē structure.
2

3. The periodic table
Non-
metals
Metals
3

4. The periodic table
Groups
Transition elements
Inner transition
elements
1
2
3
4
5
6
7
Groups
Periods
Periodic tableSummary of periodic table
4

5. 5
G roups 1 & 2: s-block.
Groups 3 – 8: p-block.
Transition elements: d-block.
Inner transition elements: f-block.
fill up:

6. 2s
3s
7s
5s
6s
4s
1s
1s
2p
3p
4p
5p
6p
3d
4d
5d
6d
4f
5f
Groups 1 &
2
Groups 3 - 8
Transition elements
Inner transition elements
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7. Consider the Group 1 elements from H to K:
H
Li Na K
The above diagrams show the similarities
between the Group 1 elements – their 1ē in
the outer energy levels.
Discuss the differences between these
elements.
Periodicity
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8. In general, atoms decrease in size across the
periods from Left to Right as a result of increased
attraction between outer energy level ē & the
nucleus.
Atoms increase in size down the groups as a
result of having an extra energy level
Decreasing size
Increasing size
Sizes of atoms
8

9. When Group 1 elements react with oxygen
they form the oxides – each with a similar
formula: H
2O Li
2O Na
2O K
2O etc.
Similarly when elements combine with the
halides (Group 7), they also form similar
formulae: NaCl MgCl
2 KF CaCl
2 LiBr etc
Forming compounds
9

10. When considering the bonding process as molecules
are formed, we need to consider the following
concepts:
 Ionisation energy
 Electronegativity
 Electron affinity
Ionisation energy: the energy required to remove an ē
from an isolated, neutral gaseous atom. Unit: kJ.mol
-1
Ionisation energy increases from from left to right in a
period and it decreases from top to bottom in a group.
Ionisation Energy:Ionization energy
10

11. Electronegativity: The measure of the force of
attraction exerted by an atom when sharing an ē
pair with another atom.
Electronegativity increases from left to right in a
period and decreases from top to bottom in a
group.
Electronegativity
11

12. Electron affinity: The energy
released when an ē is added to an
isolated, neutral, gaseous atom.
Electron affinity increases across
the period and increases down a
group
Electron affinity
Trends in periodic table
12

13. Periodic Table
Increasing metallic
properties
Increasing non-
metallic
properties.
Metalloids
13

14. Since metallic (& often reactivity) properties
increase from right to left & down the groups in
the metals, Na is thus more metallic than Mg & yet
K is more metallic than Na.
In the non-metals, the non-metallic properties
increase from left to right and up the Groups. O is
thus more non-metallic than N and S.
Determine the most metallic of the metals.
Which is the most non-metallic of all non-metals?
Metallic properties
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15. Li, Na, K, Rb, Cs & Fr
1.Soft
2.Low densities
3.Float on water
4.Silvery surfaces when cut
5.Good conductors of heat & electricity
6.Burn in air to form metal oxides
7.Metal oxides dissolve in water to form
akalis
8.React vigorously with water to form H
2 gas
9.Form cations with charge of +1 – lose ē
YouTube - Brainiac Alkali Metals
Flame tests
15

16. Group 2 – the alkali earth metals Be, Mg, Ca, St,
Ba, & Ra are:
1.Silvery in colour
2.Form cations with charge +2
3.React slowly with water
4.Good conductors of heat & electricity
5.Burn in air to form metal oxides that dissolve in water
to form the hydroxides
Group 1 & 2 metals
Ca
Mg burning in air
Calcium reacting with
water
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17. The halogens are the non-metals in Group 7
They:
1.Form diatomic molecules F
2
, Cl
2
, Br
2
, I
2
, At
2
2.Form anions with a charge of -1.
3.Have low melting and boiling points.
Halogens
Iodin
e
Chlorin
e
17

18. Group 8 are the noble gases: He, Ne, Ar, Kr, Xe
& Rn.
They:
1.Are extremely unreactive – full outer energy
levels- this can be useful.
2.Low M.P. & B. P.
He balloon taking pictures of
Earth
He
Ar
18

19. H He
Li BB
e
CNO FN
e
NaMgAlSiP SClAr
KCa
Fill in the symbol of each of the first 20
elements in their correct order.
Give yourself 1 point for each correct answer.
Now check your answers.
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