The Periodic Table Education Presentation in Yellow Style Chemistry period 3 elements.pdf.pdf

Chemistry period 3 elements thorough review with detailed information base on what is required by the cape syllabus

1. 1
H
3
Li
11
Na
19
K
37
Rb
55
Cs
87
Fr
4
Be
12
Mg
20
Ca
38
Sr
56
Ba
88
Ra
21
Sc
39
Y
57-71
89-103
22
Ti
40
Zr
72
Hf
104
Rf
23
V
41
Nb
73
Ta
105
Db
24
Cr
42
Mo
74
W
106
Sg
25
Mn
43
Tc
75
Re
107
Bh
26
Fe
44
Ru
76
Os
108
Hs
57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
A thorough research based on
Period 3 : Sodium to Argon
Elements
PERIOD 3
ELEMENTS

2. Sodium, magnesium and aluminium have a giant metallic
structure. The ions are held together by a sea of delocalised
electrons. From sodium to aluminium there is an increase in the
number of electrons donated to the sea of electrons when the
metal ions Na+, Mg2+ and Al3+ form. The greater the ionic charge
and number of delocalised electrons, the greater is the
electrostatic attraction between the ions and the electrons and the
more difficult it is to overcome these forces. So the melting points
and boiling points increase in the order Na to Mg to Al.
Structure and Melting Points

3. Phosphorus, sulphur and
chlorine have simple molecular
structures.
They have low melting points
because there are only weak van der
Waals attractive forces between the
molecules. The van der Waals forces
increase with increasing number of
electrons in the molecule and with
the number of contact points
between neighbouring molecules. So
sulphur, Ss, has a higher melting
point than phosphorus, P4. Chlorine
is a gas since it is a diatomic
molecule with a fairly small number
of electrons.
Silicon, in Group IV has the
highest melting point of the
Period 3 elements. It forms a
giant covalent lattice similar
to diamond. It takes a lot of
energy to break the large
number of strong covalent
bonds. So the melting point is
very high
Argon exists
only as isolated
atoms. The van
der Waals
forces between
these are very
low, so it has a
very low
melting

4. The density increases from Na to Al as the size of the atoms
decreases and their mass increases.
Si has a lower density than Al because it has a more open lattice
structure.
The density of P and S (and Cl and Ar as liquids) is relatively
low.
Although the atoms are heavier, the way the molecules are
packed together has an effect.
DENSITY
The density of Cl and Ar are those of their liquids.
They are gases at room temperature so have very low densities
Density depends on:
(i) the mass of the atoms
(ii) the size of the atoms
(iii) the way the atoms are packed in their lattice

5. Na, Mg and Al are all good conductors. The delocalised electrons in
the metallic structure are free to move when a voltage is applied. The
conductivity increases from Na to Al as the number of delocalised
electrons provided by each 'atom' increases (Na provides 1 electron,
Mg provides 2 and Al provides 3). The electrical conductivity of Si is
poor because it has no delocalised electrons. It is classed as a
metalloid (a substance whose electrical conductivity increases with
increase in temperature). Some of its electrons, however, can move
out of position, especially when 'contaminating' atoms are present in
its lattice. So it is called a semi-conductor. P and S hardly conduct
electricity because they are covalent molecules with no delocalised
electrons.
Electrical
Conductivity of
Period 3 Elements
The electrical conductivity (measured in siemens per metre, Sm-') of the Period 3 elements are shown below.
Chlorine and argon are gases and hardly conduct as solids.

6. Electronegativity is a measure of how well an atom attracts
electrons. It's determined by two main factors:
Nuclear charge: The number of protons in an atom, which
determines the strength of the force of attraction on
electrons
Location of electrons: The number of electrons in the
atomic shells
Electronegativity of
Period 3 Elements

7. Patterns in Atomic
and Ionic Radii in
Period 3
The covalent radius is often used as a
measure of the size of an atom.
This is half the distance between the
nuclei of two atoms of the same type.
The atomic radii decrease across Period 3. As we move across the period, each
successive element has one more proton in its nucleus. But the added electron
goes into the same quantum shell (the third electron shell). So there is no
additional shielding of outer shell electrons by the inner shells.
The increase in nuclear charge from Na to Cl pulls the electrons closer to the
nucleus. So the size of the atoms decreases across the period.

The atomic radii of the elements from sodium to chlorine

8. Metal ions are formed by losing electrons from their outer
electron shell. So their ions are smaller than their atoms. Non-
metal ions are formed by gaining electrons in their outer
electron shell. There is more repulsion between the electrons
than there is in the atom. This makes the negative ion larger
than the atom from which it is derived. The ionic radii decrease
from Nat to Si*+. As we move across the period, each
successive ion has one more proton in its nucleus. But
electronic structure is the same. The increase in nuclear charge
from Na+ to Si*+ pulls the electrons closer to the nucleus. So
the size of the ions decreases. A similar explanation (higher
nuclear charge and same electronic structure) accounts for the
decrease in ionic radius from P3- to Cl-.

9. The Reaction of Period 3 Elements With
Water
Sodium reacts vigorously:
2Na(s) + 2H20(1) → 2NaOH(ag) + H2(g)
Magnesium reacts very slowly with cold water but it reacts
readily with steam to form magnesium oxide:
Mg(s) + H20(g) → MgO(s) + H2(g)
Aluminum does not react with hot or cold water but it
reacts with steam:
2Al(s) + 3H20(g) → Al2O3(s) + 3H2(g)
- Silicon, phosphorus and sulphur do not react.
They are insoluble in water.
Chloride dissolves slightlyin water and then reacts to form a
mixture of hydrochloric and chloric (1) acid
C1,(g) + H,0(1) = 2H*(aq) + Cl (aq) + ClO-(aq)

10. The reaction
of Period 3
elements with
oxygen
Sodium reacts vigorously when heated to
form sodium oxide, Na20 (although the final
stable product is sodium peroxide, Na202):
2Na(s) + 02(g) → Na2O2(s)
Magnesium and aluminium react vigorously
with oxygen to form oxides:
2Mg(s) + 02(g) → MgO(s) and 4Al(s) + 302(g)
→ 2A1203(s)
Silicon reacts slowly with oxygen:
Si(s) + 02(g) → SiO2(s)
Phosphorus reacts vigorously with oxygen
to from phosphorus(v) oxide:
4P(s) + 502(g) → 2P2O5(s)
Sulphur burns steadily in oxygen:
S(s) + 02(g) → SO2(g)
Chlorine and argon do not combine directly
with oxygen.

11. Apart from argon (and chlorine
itself) all Period 3 elements react
with chlorine.
Sodium, magnesium and
aluminium react vigorously to
form NaCl, MgCl2, and AlCl3,
respectively ich are onic solids.
Silicon, phosphorus
With Sodium: Na(s) + Cl2→2NaCl(s)
With Silicon: Si(s) + 2Cl,(g) →SiCl(l)
With phosphorus: 2P(s) + 5C1,(g) →
2PC15(s)
With sulphur: 2S(s) + Cl2(g) →
S2Cl2(l)
The Reaction of
Period 3
Elements With
Chlorine

12. The oxidation number (or oxidation
state) of an element in a compound
indicates the degree of oxidation (loss of
electrons) or reduction (gain of
electrons) relative to the neutral atom.
The oxidation numbers of elements can
vary depending on whether they are part
of an oxide or chloride, and the rules
governing their assignment depend on
the nature of the compound and the
elements involved.
1. Sodium (Na):
- Oxide: Na2O (Na+1, O-2)
- Chloride: NaCl (Na+1, Cl-1)
2. Magnesium (Mg):
- Oxide: MgO (Mg+2, O-2)
- Chloride: MgCl2 (Mg+2, Cl-1)
3. Aluminum (Al):
- Oxide: Al2O3 (Al+3, O-2)
- Chloride: AlCl3 (Al+3, Cl-1)
4. Silicon (Si):
- Oxide: SiO2 (Si+4, O-2)
- Chloride: SiCl4 (Si+4, Cl-1)
Oxidation
Number

13. 5. Phosphorus (P):
- Oxide: P2O5 (P+5, O-2), P2O3 (P+3, O-2)
- Chloride: PCl5 (P+5, Cl-1), PCl3 (P+3, Cl-1)
6. Sulfur (S):
- Oxide: SO2 (S+4, O-2), SO3 (S+6, O-2)
- Chloride: SCl2 (S+2, Cl-1), SCl4 (S+4, Cl-1)
7. Chlorine (Cl):
- Oxide: Cl2O (Cl+1, O-2), ClO2 (Cl+4, O-2)
- Chloride: Cl2 (Cl0)
8. Argon (Ar):
- Noble gases do not typically form oxides or
chlorides.
Oxidation
Number

14. Reactions of
Oxide with
Water
1. Na2O: Reacts vigorously with water to form sodium hydroxide
(NaOH).
- Na2O + H2O → 2NaOH
2. MgO: Reacts slowly with water to form magnesium hydroxide
(Mg(OH)2).
- MgO + H2O → Mg(OH)2
3. Al2O3: Insoluble in water, but reacts with acid or base.
4. SiO2: Insoluble in water.
5. P2O5: Reacts with water to form phosphoric acid (H3PO4).
- P2O5 + 3H2O → 2H3PO4
6. SO2: Reacts with water to form sulfurous acid (H2SO3).
- SO2 + H2O → H2SO3
7. SO3: Reacts with water to form sulfuric acid (H2SO4).
- SO3 + H2O → H2SO4

15. Reactions of Chlorides with Water
1. NaCl: Soluble in water, no reaction.
2. MgCl2: Soluble in water, no reaction.
3. AlCl3: Reacts with water to form aluminum hydroxide (Al(OH)3) and hydrochloric acid (HCl).
- AlCl3 + 3H2O → Al(OH)3 + 3HCl
4. SiCl4: Reacts with water to form silicic acid (H2SiO3) and hydrochloric acid (HCl).
- SiCl4 + 2H2O → H2SiO3 + 4HCl
5. PCl5: Reacts with water to form phosphoric acid (H3PO4) and hydrochloric acid (HCl).
- PCl5 + 4H2O → H3PO4 + 5HCl
6. SCl2: Reacts with water to form sulfurous acid (H2SO3) and hydrochloric acid (HCl).
- SCl2 + 2H2O → H2SO3 + 2HCl

16. Trends in the
acid/base behavior of
the oxides and
hydroxides
1. Basic Oxides and Hydroxides (Group 1 to
Group 2)
o Elements:
Sodium (Na) and Magnesium (Mg).
o These elements form oxides and hydroxides
that are basic due to their metallic character.
o Reactions:
o Sodium oxide (Na2ONa_2ONa2​O) reacts with
water to form sodium hydroxide:
Na2O + H2O 2NaOH-
Sodium hydroxide is a strong base and
dissociates completely in water:
NaOH Na+ + OH-
o Magnesium oxide (MgO) is less basic due to
the higher charge density of Mg2+ reacts with
water to form magnesium hydroxide:
MgO + H2O Mg(OH)2
Magnesium hydroxide is sparingly soluble,
releasing only a small concentration of OH-

17. Trends in the acid/base
behavior of the oxides
and hydroxides
3. Acidic Oxides (Group 15 to Group
17)
• Elements: Phosphorus (P), Sulfur
(S), and Chlorine (Cl).
• These elements form oxides that
are acidic due to their non-metallic
character.
• Reactions:
o Phosphorus pentoxide (P4O10 ​)
reacts with water to form phosphoric
acid:
P4O10 + 6H2O 4H3PO4
o Sulfur trioxide (SO3​) reacts with
water to form sulfuric acid:
SO3 + H2O H2SO4
2. Amphoteric Oxides (Group 13 to Group 14)
Element: Aluminium (Al) and Silicon (Si).
Aluminium oxide (Al2O3 ) is amphoteric, meaning it
reacts with both acids and bases:
With acid: Al2O3 + 6HCl 2AlCl3 + 3H2O
With base: Al2O3 + 2NaOH + 3H2O 2Na[Al(OH)4]
Silicon dioxide (SiO2 ) is weakly acidic.
It reacts with strong bases (but not with water directly) to
form silicates: SiO2 + 2NaOH Na2SiO3 + H2O

18. Chlorides of Period
3 Elements
1. Chlorides of Period 3 Elements
a) Sodium Chloride (NaCl) and Magnesium Chloride (MgCl_2): Ionic
•Bonding: Strongly ionic.
•Reasoning:
•Sodium and magnesium are highly electropositive metals with low
electronegativities.
•Chlorine is highly electronegative (3.16 on the Pauling scale).
•Large electronegativity differences (\Delta EN > 1.7 ) result in ionic bonding.
•Sodium (Na+) and magnesium (Mg2+) have small ionic radii, favoring strong
electrostatic interactions.

19. Oxide of Period
3 Elements
a) Sodium Oxide (Na2O) and Magnesium Oxide (MgO): Ionic
•​Bonding: Strongly ionic.
•​Reasoning:
• Oxygen is highly electronegative (3.44), and the electronegativity differences
with sodium ( \Delta EN \approx 2.6 ) and magnesium ( \Delta EN \approx 2.3 )
are very large.
• Sodium and magnesium form Na+ and Mg2+, which interact with O2- to form
ionic lattices.
• The small ionic radii of Na+, Mg2 and O2-enhance the ionic bond strength.

20. Uses of some of the
compounds of Aluminum
and Phosphorus
1. Aluminum Oxide (Al₂O₃)
Use:
Manufacture of Aluminum: Aluminum oxide is the primary compound
from which aluminum metal is extracted through the Bayer process.
Abrasives: It is used as an abrasive material in sandpaper, grinding
wheels, and polishing agents because of its hardness.
Ceramics: Aluminum oxide is used to make advanced ceramics (e.g., in
electronic devices or as insulators in high-temperature applications).
Refractories: It is used in materials that can withstand high temperatures.

21. 2. Aluminum Sulfate (Al₂(SO₄)₃)
Use:
Water Treatment: Aluminum sulfate is
commonly used in water purification
processes as a flocculant to remove
impurities.
Paper Manufacturing: It is used in the paper
industry in the papermaking process,
particularly in sizing agents to improve the
strength of paper.
Dye Fixative: Used in the textile industry to
fix dyes onto fabrics.

3. Aluminum Chloride (AlCl₃)
Use:
Catalysis: It is an important catalyst in
organic chemistry, especially in
Friedel-Crafts reactions for the
synthesis of aromatic compounds.
Chemical Synthesis: Used in the
production of polymers like polyvinyl
chloride (PVC).
Electrolytic Processes: Used in the
production of aluminum metal through
electrolysis.

22. 4. Aluminum Phosphate (AlPO₄)
Use:
Catalysts: It is used in the
petroleum industry as a catalyst
in refining processes.
Refractories: Aluminum
phosphate is used in refractory
materials, especially in high-
temperature environments.
Absorbents: Can be used as an
adsorbent material in water
purification and in some chemical
applications.
5. Phosphoric Acid (H₃PO₄)
Use:
Fertilizers: Phosphoric acid is a key ingredient
in the production of phosphate fertilizers,
which are essential for agricultural growth.
Food and Beverages: It is used as an acidity
regulator in soft drinks, processed foods, and
as a leavening agent.
Cleaning Products: Used in rust removal and
as a cleaning agent in industrial and
household applications.
Industrial Chemicals: Phosphoric acid is
involved in producing detergents, water
treatment chemicals, and flame retardants.

23. 6. Phosphine (PH₃)
Use:
Pesticides: Phosphine gas is used as a fumigant to control
pests in stored grain and other agricultural products.
Semiconductors: Phosphine is used in the production of
semiconductors, particularly in the doping of silicon and
gallium arsenide (GaAs) to alter their electrical properties.

7. Aluminum Phosphide (AlP)
Use:
Pesticide: Aluminum phosphide is used as a fumigant to control pests in stored
grains and in other agricultural commodities. It releases phosphine gas upon
contact with moisture, which is toxic to pests.
Rodenticide: Also used in pest control for rodents in some applications.

24. 8. Ammonium Phosphate ((NH₄)₃PO₄)
Use:
Fertilizers: One of the most common forms of phosphate
fertilizer, ammonium phosphate provides essential nutrients
(nitrogen and phosphorus) for plant growth.
Fire Extinguishers: It is used in dry chemical fire
extinguishers, especially for Class A, B, and C fires, because
of its flame-retardant properties.

9. Aluminum Phosphide (AlP)
Use:
Fumigant: Similar to phosphine, aluminum phosphide is
widely used as a fumigant in pest control, particularly in
grain storage and in agricultural commodities. It releases
toxic phosphine gas when it reacts with moisture.

25. 10. Aluminum Hydroxide (Al(OH)₃)
Use:
Antacids: Aluminum hydroxide is used as an active
ingredient in some antacid medications to neutralize stomach
acid.
Water Purification: It is used in water treatment as a
coagulant to remove suspended particles.
Flame Retardant: It is also used in fire-resistant coatings and
materials, due to its ability to release water vapor when
heated, which helps to suppress flames.