EXPERIMENT 6: PROPERTIES OF SOME REPRESENTATIVE ELEMENTS
Materials:
Bunsen burner
Wire Gauze Pair of tongs
Nichrome wire loop
Deflagrating spoon
Beakers (150, 400, 600 mL)
250 mL flask Small test tubes (6)
Spatula
Test tube rack
Chemicals:
0.10 M solutions of LiCl, NaCl, KCl, CaCl2, BaCl2, SrCl2
0.10 M solutions of KCl, KBr, KI
Metals : Li, Na, K, Ca, Mg ribon
Oxides: Lime (CaO), Sodium Peroxide (Na2O2)
Phenolphthalein indicator Universal Indicator Dry Ice Sulfur (S)
Aqueous solutions of : Cl2 (aq) , Br2 (aq), I2 (aq)
Cyclohexane
Safety: Safety goggles have to be worn all the time during the lab.
INTRODUCTION
Flame Tests
When atoms or ions are heated, they gain kinetic energy; some electrons may absorb enough energy (photon) to
“jump” to higher energy levels (excited state). Excited electrons don’t last long in the higher energy levels
(unstable state); the electrons will “fall” back to their ground state and release the extra energy (equal to the
difference between ground state and excited state).
When the energy released in the visible light spectrum, a certain color can be seen. The color of the light
depends on the energy change that took place (wavelength and frequency). Many metallic ions exhibit
characteristic colors when heated; therefore, the color of the light can be used to identify certain elements, that’s
why these colors are called fingerprint of elements.
Alkali Metals Properties and Reactivity
The alkali metals are a group in the periodic table. In the modern IUPAC nomenclature, the alkali metals are
called the Group IA elements. The alkali metals contain lithium (Li), sodium (Na), potassium (K), rubidium
(Rb), cesium (Cs) and francium (Fr).[1] (Hydrogen (H), although nominally also a member of Group IA very
rarely exhibits behavior comparable to the alkali metals.) This group lies in the s-block of the periodic table.
The alkali metals provide one of the best examples of group trends in properties in the periodic table, with well
characterized homologous behavior down the group.
All of the alkali metals discovered, as of 2011, are naturally occurring (although francium is the rarest naturally
occurring element), and share similar properties: they are all highly reactive metals under standard conditions.
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So far, experiments have been conducted to attempt the synthesis of the next member of the group,
ununennium (Uue), but these have all met with failure. However, since ununennium is the first period 8
element and only the first element on the periodic table that has not been discovered yet, it is likely to be
discovered in the near future.
Like other groups, the members of this family show patterns in its electronic configuration, especially the
outermost shells, resulting in trends in chemical behavior:
Z Element No. of electrons/shell Electron configuration
1 hydrogen 1
1s1
3 Lithium
2, 1
[He]2s1
11 Sodium
2, 8, 1
[Ne]3s1
19 potassium 2, 8, 8, 1
[Ar]4s1
37 rubidium 2, 8, 18, 8, 1
[Kr]5s1
55 cesium
[Xe]6s1
2, 8, 18, 18, 8, 1
87 francium 2, 8, 18, 32, 18, 8, 1
[Rn]7s1
All of the alkali metals are notable for their vigorous reactions with water, and these reactions become
increasingly vigorous when going down their column in the periodic table towards the heaviest alkali metals,
such as cesium. Their chemical reactions with water are as follows:
Alkali metal + water → Alkali metal hydroxide + hydrogen gas
For a typical example (M represents an alkali metal):
2 M (s) + 2 H2O (l) → 2 MOH (aq) + H2 (g)
Alkaline Earth Metals
The alkaline earth metals are a series of elements comprising Group 2 (IUPAC style) (Group IIA) of the
periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra).[1]
This specific group in the periodic table owes its name to their oxides that simply give basic alkaline solutions.
These oxides melt at such high temperature that they remain solids (“earths”) in fires. The alkaline earth metals
provide a good example of group trends in properties in the periodic table, with well-characterized homologous
behavior down the group. With the exception of Be and Mg, the metals have a distinguishable flame color,
orange for Ca, bright red for Sr, green for Ba and crimson red for Ra.
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Like other groups, the members of this family show patterns in its electron configuration, especially the
outermost shells resulting in trends in chemical behavior:
Z
Element
4 Beryllium
No. of electrons/shell
2, 2
12 Magnesium 2, 8, 2
20 Calcium
2, 8, 8, 2
38 Strontium
2, 8, 18, 8, 2
56 Barium
2, 8, 18, 18, 8, 2
88 Radium
2, 8, 18, 32, 18, 8, 2
The alkaline earth metals are silver colored, soft metals, which react readily with halogens to form ionic salts,
and with water, though not as rapidly as the alkali metals, to form strong alkaline (basic) hydroxides. For
example, where sodium and potassium react with water at room temperature, magnesium reacts only with steam
and calcium with hot water:
Mg + 2 H2O → Mg(OH)2 + H2
Beryllium is an exception: It does not react with water or steam, and its halides are covalent.
Reaction of a metal oxide with water produces a metal hydroxide ; that is, a strong base. Reaction of a
nonmetal oxide with water produces an oxyacid in which the nonmetal is in the same oxidation state as in the
oxide you started with. Both of these are combination reactions, and both can be reversed by heating the
products. Metal hydroxides decompose on heating to give the metal oxide and water, and oxyacids decompose
on heating to give water and the nonmetal oxide in the appropriate oxidation state.
Metal Oxide reactions
The oxides of metals are basic. If a metal oxide dissolves in water, it will form a metal hydroxide.
Metal Oxide + Water → Metal Hydroxide(Base)
For example,
BaO(s)
K2O(s)
Na2O(s)
MgO(s)
+ H2O(l)
+ H2O(l)
+ H2O(l)
+ H2O(l)
3
→ Ba(OH)2(aq)
→ 2 KOH(aq)
→ NaOH(aq)
→ Mg(OH)2(aq)
Non-Metal Oxide reactions
The oxides of non-metals are acidic. If a non-metal oxide dissolves in water, it will form an acid.
Non-Metal Oxide + Water → Oxyacid (acid)
For example,
SO3(g) + H2O(l) → H2SO4(aq)
N2O3(g) + H2O(l) → HNO2(aq)
SO2(g) + H2O(l) → H2SO3(aq)
Cl2O5(g) + H2O(l) → HClO3(aq)
The non-metal oxides can be neutralized with a base to form a salt and water.
Non-Metal Oxide + Base → Salt + Water
For example,
SO3(g) + Ba(OH)2(aq) → BaSO4(aq) + H2O(l)
P4O10(s) + 12 NaOH(aq) → 4 Na3PO4(aq) + 6 H2O(l)
Reactivity of Halogens
On the basis that the most reactive element displaces a least reactive element the reactivity order must be:
chlorine > bromine > iodine
The word and symbol equations for the 1 - 3 DISPLACEMENT REACTIONS on the diagram are given
below.
1. chlorine + potassium bromide  potassium chloride + bromine
Cl2(aq) + 2KBr(aq)  2KCl(aq) + Br2(aq)
2. chlorine + potassium iodide  potassium chloride + iodine
Cl2(aq) + 2KI(aq)  2KCl(aq) + I2(aq)
3. bromine + potassium iodide  potassium bromide + iodine
Br2(aq) + 2KI(aq)  2KBr(aq) + I2(aq)
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The halogen molecule is the electron acceptor (the oxidizing agent) and is reduced by electron gain to form a
halide ion The halide ion is the electron donor (the reducing agent) and is oxidized by electron loss to form a
halogen molecule.
chlorine molecule + bromide ion  chloride ion + bromine molecule
ionically the redox equations are written ...
1. Cl2(aq) + 2Br-(aq)  2Cl-(aq) + Br2(aq)
because the potassium ion, K+, is a spectator ion, that is, it does not take part in the reaction. The other two
possible reaction equations involving (ii) chlorine + iodide and (iii) bromine + iodide, are similar to the example
above.
2. Cl2(aq) + 2I-(aq)  2Cl-(aq) + I2(aq)
3. Br2(aq) + 2I-(aq)  2Br-(aq) + I2(aq)
Solubility of Halogens in Polar and Nonpolar Solvents:
The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style (formerly:
VII, VIIA) of the periodic table, comprising fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine
(At). The artificially created element 117, provisionally referred to by the systematic name ununseptium, may
also be a halogen.
The group of halogens is the only periodic table group which contains elements in all three familiar states of
matter at standard temperature and pressure.
Like other groups, the candidates of this family show patterns in its electron configuration, especially the
outermost shells resulting in trends in chemical behavior:
Z Element No. of electrons/shell
9 fluorine 2, 7
17 chlorine 2, 8, 7
35 bromine 2, 8, 18, 7
53 iodine
2, 8, 18, 18, 7
85 astatine 2, 8, 18, 32, 18, 7
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Fluorine reacts vigorously with water to produce oxygen (O2) and hydrogen fluoride (HF)
2 F2(g) + 2 H2O(l) → O2(g) + 4 HF(aq)
Chlorine has minimal solubility of 0.7g Cl2 per kg of water at ambient temperature (21oC) Dissolved chlorine
reacts to form hydrochloric acid (HCl) and hypochlorous acid, a solution that can be used as a disinfectant or
bleach:
Cl2(g) + H2O(l) → HCl(aq) + HClO(aq)
Bromine has a solubility of 3.41 g per 100 g of water, but it slowly reacts to form hydrogen bromide (HBr) and
hypobromous acid (HBrO):
Br2(g) + H2O(l) → HBr(aq) + HBrO(aq)
Iodine, however, is minimally soluble in water and does not react with it. However, iodine will form an
aqueous solution in the presence of iodide ion (I -), such as by addition of potassium iodide (KI), because the
triiodide ion is formed (I3 -).
Cyclohexane is a non-polar cyclic hydrocarbon; on the principle of "like dissolves like" Cyclohexane will
dissolve other non-polar compounds quite well. Water is a polar molecule, as are all halogens as exemplified by
the simplest common halogen of all, hydrochloric acid. Halogen acids, common refrigerants, even some
anesthetics are all polar molecules and therefore dissolve fairly well in other polar liquids, including water.
Procedure:
PART  Flame Tests (Recommended as Instructor Demonstration)
1. Obtain the 0.1 M solutions of the following salts:
LiCl, NaCl, KCl, CaCl2, BaCl2, and SrCl2.
2. Ignite a Bunsen burner flame.
3. Before you dip each loop end of the wire into its particular solution,
heat the loop end of the wire in the flame until it no longer imparts a
color to the flame
4. Then dip the loop into the salt solution and hold it in the oxidizing
portion of the flame, the hottest part.
5. Observe and record the color(s) imparted to the flame by the metal
ion of each salt.
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 Make certain each salt
solution bottle has its own
wire (with a loop at one end.)
 Take care not to mix up the
wires and make to place them
into correct solutions.
PART  A) Alkali Metals: Li, Na, K (Instructor Demonstration)
1. In a 600 mL beaker put ~150 mL deionized
H2O.
2. Add two drops of phenolphthalein indicator to the
deionized H2O and record.
3. Cut a small piece (pea size) of Li metal
using a spatula. Observe the freshly cut surface, and
compare it to the exposed surface. Report
observations.
 Universal indicator may be substituted for
phenolphthalein indicator.
 Do not touch the alkali metals. Use forceps
when handling the metals.
 Remove excess kerosene by pressing the
metal against a paper towel.
 Keep the beaker at arm’s length.
4. Drop the metal into the beaker, and
immediately cover it with wire gauze.
5. Record observations, the color of the final
solution.
6. Repeat and record the above procedure
with Na and K metals.
PART  B) Alkaline Earth Metals: Mg, Ca
1. In a large test tube add ~3 mL of deionized H2O plus two drops of
phenolphthalein indicator, and record the color of the solution.
2. Cut ~ I cm of clean Mg ribbon and drop it into the test tube.
Check the surface of the Mg and record your observations.
3. In a 250 mL beaker put ~100 mL deionized H2O, add two drops of
phenolphthalein indicator to the deionized H2O.
4. Drop a small piece of Ca metal. Observe and record.
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 If nothing is observed, you
may gently heat the test
tube, and write your
observations (bubbles,
color change etc.)
 Work in the exhaust hood,
with the safety shield pulled
down.
PART  - Oxides of Selected Elements
A) Basic Metal Oxides
1. Put 25-30 mL of deionized water into 100 mL beaker. Add 2 drops of
universal indicator in water.
2. Cut ~ 5 cm of Mg ribbon. Ignite the Mg ribbon, while
you are holding it above the beaker with a pair of tongs.
3. Let the ashes fall into the beaker,
4. Stir the solution for a while.
5. Write equations for both reactions.
 Never look directly at the
flame. The intense bright
light is quite damaging to
the eyes.
6. Add 2 drops of universal indicator in 5 mL of H2O in a
large test tube. Observe the color.
7. Add sodium peroxide,Na2O2, with the tip of a spatula, stir.
8. Repeat steps 6-8 with lime, CaO.
PART IV. Properties of Halogens: (Recommended as Instructor Demonstration)
PART IV. A) Solubility of Halogens in Polar & Nonpolar Solvents: Cl2, Br2, I2
1. In a large test tube add 1 mL, ~ drops, of chlorine water, Cl2(aq).
Note and report the color of Cl2 in water.
2. Add ~ 10 drops of cyclohexane,C6H12, to the test tube. Shake well.
Allow the layers to separate. Note and report the color of the Cl2 in
C6H12 solution.
3. Repeat steps 1 and 2 for Br2 and I2.
12-
4. Keep all three test tubes on the test tube rack to be
used for comparative purposes in part IV B).
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 The elemental halogens are
toxic avoid breathing the
fumes!
 Dispose of cyclohexane
solutions in waste bottle.
PART IV. B) Relative Reactivity of Halogens: Cl2, Br2, I2

1. Obtain two small test tubes. Add 10 drops of Cl2(aq) in each
test tube. Observe and report color.
2. Add ~ 10 drops of 0.1 M KBr to one test tube and 0.1 M K to
the second test tube. Gently shake.
3. Observe and report color of each test tube.
4. Add 10 drops of cyclohexane, C6H12, to the mixtures in each
test tube, and shake well.
5. Note the color of organic layer and report.
6. Obtain two small test tubes. Add 10 drops of Br2(aq) in each test tube.
Observe and report color.
7. Add ~ 10 drops of 0.1 M KCl to one test tube and 0.1 M K to
the second test tube. Gently shake.
8. Observe and report color of each test tube.
9. Add 10 drops of C6H12 to the mixtures in each test tube, and
shake well.
10. Note the color of organic layer and report.
11. Obtain two small test tubes. Add 10 drops of 2(aq) in each test tube.
Observe and report color.
12. Add ~ 10 drops of 0.1 M KCl to one test tube and 0.1 M KBr to the
second test tube. Gently shake.
13. Observe and report color of each test tube.
14. Add 10 drops of C6H12 to the mixtures in each test tube, and shake well.
15. Note the color of organic layer and report.
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If a reaction occurs,
use the solutions from
Part IV. A) to identify
the halogens
produced.
 Dispose all
cyclohexane
solutions in the
waste jar.
EXPERIMENT 6: PROPERTIES OF SOME REPRESENTATIVE ELEMENTS
REPORT FORM
Name ___________________________
Instructor ________________________
Date ____________________________
Partner’s Name: ___________________
RESULTS / OBSERVATIONS (Show ALL calculations when appropriate)
PART A:
PART I.) Flame Test
SALT
Element which imparts its color to flame
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Flame Color
PART III. A) Reactions of ALKALI METALS
Group #
& Name
Metal
Period #
Color
before
rxn.
Color
after
rxn.
Balanced Equation
Li
Na
K
PART III. B) Reactions of ALKALINE EARTH METALS
Group #
& Name
Metal
Period #
Color
before
rxn.
Color
after
rxn.
Mg
Ca
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Balanced Equation
PART IV. A) Solubility of Halogens in Polar & Nonpolar Solvents: Cl2, Br2, I2
Halogen
Color in Water
Color in Cyclohexane
Cl2
Br2
I2
PART IV. B) Relative reactivity of Halogens: Cl2, Br2, I2
Halogen
Salt
Solution
Added
Color of
Aqueous
Solution
Color
Is there a
of C6H12
rxn.?
Solution
Cl2(aq)
KBr (aq)
Cl2 (aq)
K(aq)
Br2(aq)
KCl(aq)
Br2(aq)
K(aq)
2 (aq)
KCl(aq)
2 (aq)
KBr(aq)
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Balanced Chemical Equation
EXPERIMENT 6: PROPERTIES OF SOME REPRESENTATIVE ELEMENTS
Name:____________________________
Pre-Laboratory Questions and Exercises
Due before lab begins. Answer in the space provided.
1. Write symbols for the following elements;
a) Alkali metals
b) Alkaline earth metals
c) Halogens
2. Write a balanced reaction for Li, Na, and K with water.
3. Write a balanced reaction for Cl2, Br2, and I2 with water.
4. Name the followings;
I
I2
I-
I3-
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EXPERIMENT 6: PROPERTIES OF SOME REPRESENTATIVE ELEMENTS
Name:____________________________
Post-Laboratory Questions and Exercises
Due after completing the lab. Answer in the space provided.
1. Define polarity and give an example of polar and non-polar compound.
2. What is the meaning of “Like Likes Like”?
3. Complete the following reactions.
a) CaO + H2O 
b) Li2O + H2O 
c) Mg + H2O 
d) K + H2O 
e) SO2 + H2O 
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