Chemical Properties and Periodicity
ALKALI METALS:
Physically they are solid, soft, malleable, conductors
and have low density (large atoms) and low melting
points compared with other metals (only 1 econtributes to the metallic bond).
These last two properties decrease as we move down
the group, because the size of the atom increases.
Have 1 e- in the outer level
Form 1+ ions
The alkali metals are very reactive
Chemical Properties and Periodicity
Some reactions of alkali metals:
They react with oxygen or with halogens to form
binary ionic compounds:
4Li (s) + O2(g)
2K(s) + Cl2 (g)
2Na(s) + Br2 (l)
2Li2O(s)
2KCl(s)
2NaBr(s)
They react vigorously with water:
Na(s) + 2H2O(l)
2NaOH(aq) + H2(g)
They must be stored in kerosene because they react explosively
with water from the atmosphere…
…Reactions of alkali metals
This reaction is the same for all alkali metals but it
becomes more vigorous as we move down the group
(Slow with Li, vigorous with Na and violent with K).
M(s) + 2H2O(l)
2MOH(aq) + H2(g)
M+(aq) and OH-(aq)
Very alkaline
(basic) solution
Basic Information
http://www.chemicalelements.com/elements/li.html
Name: Lithium
Symbol: Li
Atomic Number: 3
Atomic Mass: 6.941 amu
Melting Point: 180.54 °C (453.69 °K, 356.972 °F)
Boiling Point: 1347.0 °C (1620.15 °K, 2456.6 °F)
Number of Protons/Electrons: 3
Number of Neutrons: 4
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: 0.53 g/cm3
Color: silvery
Number of Energy Levels: 2
Atomic Structure
First Energy Level: 2
Second Energy Level: 1
ISOTOPES
Isotope
Li-6
Li-7
Half Life
Stable
Stable
http://www.westga.edu/~chem/courses/desc.inorg/490Jan14/sld005.htm
FACTS
Date of Discovery: 1817
Discoverer: Johann Arfvedson
Name Origin: From the Greek word lithos (stone)
Uses: batteries, ceramics, lubricants
Obtained From: passing electric charge through melted lithium
chloride, spodumene
http://www.chemicalelements.com/elements/li.html
Basic Information
Atomic Structure
Name: Sodium
Symbol: Na
Atomic Number: 11
Atomic Mass: 22.98977 amu
Melting Point: 97.8 °C (370.95 °K, 208.04001 °F)
Boiling Point: 552.9 °C (826.05005 °K, 1027.2201 °F)
Number of Protons/Electrons: 11
Number of Neutrons: 12
Number of Energy Levels: 3
Classification: Alkali Metal
Crystal Structure: Cubic
First Energy Level: 2
3
Density @ 293 K: 0.971 g/cm
Second Energy Level: 8
Color: silvery
Third Energy Level: 1
http://www.chemicalelements.com/elements/na.html
Isotopes
http://www.chemicalelements.com/elements/na.html
Isotope
Na-22
Half Life
2.6 years
Na-23
Stable
Na-24
14.96 hours
Facts
http://www.westga.edu/~chem/courses/desc.inorg/490Jan14/sld005.htm
Date of Discovery: 1807
Discoverer: Sir Humphrey Davy
Name Origin: soda (Na2CO3)
Symbol Origin: From the Latin word natrium (sodium)
Uses: medicine, agriculture
Obtained From: table salts and other foods
http://www.chemicalelements.com/elements/k.html
Basic Information
Name: Potassium
Symbol: K
Atomic Number: 19
Atomic Mass: 39.0983 amu
Melting Point: 63.65 °C (336.8 °K, 146.57 °F)
Boiling Point: 774.0 °C (1047.15 °K, 1425.2 °F)
Number of Protons/Electrons: 19
Number of Energy Levels: 4
Number of Neutrons: 20
Classification: Alkali Metal
First Energy Level: 2
Crystal Structure: Cubic
Second Energy Level: 8
Density @ 293 K: 0.862 g/cm3
Third Energy Level: 8
Color: silvery
Fourth Energy Level: 1
http://www.westga.edu/~chem/courses/desc.inorg/490Jan14/sld006.htm
Isotopes
Isotope Half Life
K-39
Stable
K-40
1.28E9 years
K-41
Stable
K-42
12.4 hours
K-43
22.3 hours
Facts
Date of Discovery: 1807
Discoverer: Sir Humphrey Davy
Name Origin: potash
Symbol Origin: From the Latin word
Uses: glass, soap
Obtained From: minerals (carnallite
http://www.chemicalelements.com/elements/k.html
If you want information about Rb, Cs and Fr use the following links
Rb: http://www.chemicalelements.com/elements/rb.html
Cs: http://www.chemicalelements.com/elements/cs.html
Fr: http://www.chemicalelements.com/elements/fr.html
http://www.westga.edu/~chem/courses/desc.inorg/490Jan14/sld006.htm
The Halogens
All the halogens exist in the form of diatomic
molecules: F2, Cl2, Br2, I2, At2
Physically the first two, F2, Cl2, are gases, Br2 is liquid,
I2 is a solid that sublimates at room temperature.
They show different colors, for example Chlorine is
green, Iodine is black and Bromine is red-brown.
They are slightly soluble in water (because they are non
polar): X2 + H2O  H+ + X- + HOX
In polar solvens (like H2O and ethanol) Iodine forms a
brown solution, but in non-polar solvents it forms a
purple solution.
Some reactions of halogens
They have 7 e- in the outer level, so they need 1 e- to
become isoelectronic with a noble gas.Therefore they
form 1- ions.
They react with metals to form binary compounds:
2Li (s) + F2(g)
2K(s) + Cl2 (g)
2Na(s) + Br2 (l)
2LiF(aq)
2KCl(aq)
2NaBr(aq)
These halides are usually white and soluble in water
The insoluble halides are the ones formed with silver like
AgCl, AgBr and AgI : Ag+(aq) + X-(aq) AgX(s).
The halides of Lead (II) are insoluble but can be dissolved
hot water. Lead (II) iodide (PbI2) is yellow.
Cont…Some reactions of halogens
The previous reactions and properties can be used to
test for the presence of halides as follows:
•First add nitric acid to prevent other substances like
carbonates to form precipitates and confuse the
results.
•Then add silver nitrate.
•NaCl(aq) + AgNO3 (aq)  NaNO3(aq) + AgCl(s)
•The formation of a precipitate indicates the
presence of chloride, iodide or bromide ions.
(Fluorine doesn’t form a precipitate)
• AgCl(s) is white and darkens with sunlight
• AgBr(s) is white
• AgI(s) is pale yellow
Other reactions of halogens
The halogens can undergo
SINGLE REPLACEMENT REACTIONS:
X2 + MY
Y2 + MX
Example:
F2 (g) + 2NaCl(aq)
Cl2(g) + 2NaF(aq)
Review of Single
Replacement Reactions
A +BC  AC + B
An element takes the place of
another element in a compound.
It could be a metal taking the place of another
metal or hydrogen.
Mg(s) + FeSO4(aq)
MgSO4 (aq) + Fe(s)
Magnesium is more active than Iron
Fe(s) + MgSO4 (aq)
N.R.
…cont…Single Replacement
It could be also a halogen taking
the place of another halogen.
Cl2(g) + 2KBr(aq)
2 KCl(aq) + Br2 (aq)
Chlorine is more active than Bromine!
Br2 (aq) + KCl(aq)
N.R.
Oxidizing power
An atom or ion is oxidized when it loses
electrons in a reaction
An atom or ion is reduced when it gains
electrons in a reaction
Halogens tend to be reduced to form the
negative ion (halide)
An atom that tends to be reduced is an oxidizing agent,
because it makes other elements to be oxidized.
Halogens act as oxidizing agents in a single
replacement reaction
The oxidizing power decreases down a group because
they have less tendency to be reduced (becoming negative).
…Cont…Oxidizing power
That is why a higher halogen in the PT can
replace a lower halogen and form its salt.
Cl2(g) + 2KI(aq)
2 KCl(aq) + I2 (aq)
This could be also expressed in the following way:
Cl2(g) + 2I-(aq)
2 Cl-(aq) + I2 (aq)
But a lower halogen in the PT cannot replace
A higher halogen
KCl(aq) + I2 (aq)
NR
2 Cl-(aq) + I2 (aq)
Cl2(g) + 2I-(aq)
Basic Information
http://www.chemicalelements.com/elements/f.html
Name: Fluorine
Symbol: F
Atomic Number: 9
Atomic Mass: 18.998404 amu
Melting Point: -219.62 °C (53.530006 °K, -363.31598 °F)
Boiling Point: -188.14 °C (85.01 °K, -306.652 °F)
Number of Protons/Electrons: 9
Number of Neutrons: 10
Classification: Halogen
Crystal Structure: Cubic
Density @ 293 K: 1.696 g/cm3
Number of Energy Levels: 2
Color: Greenish
First Energy Level: 2
Second Energy Level: 7
Isotopes
Isotope Half Life
F-18 1.8 hours
F-19 Stable
Facts
Date of Discovery: 1886
Discoverer: Joseph Henri Moissan
Name Origin: From the Latin word fluo (flow)
Uses: Refrigerants
Obtained From: mineral fluorite
Basic Information
Name: Chlorine
Number of Energy Levels: 3
Symbol: Cl
Atomic Number: 17
First Energy Level: 2
Atomic Mass: 35.4527 amu
Second Energy Level: 8
Melting Point: -100.98 °C
Third Energy Level: 7
(172.17 °K, -149.764 °F)
Boiling Point: -34.6 °C (238.55
°K, -30.279997 °F)
Number of Protons/Electrons:
17
Number of Neutrons: 18
Classification: Halogen
Crystal Structure:
Orthorhombic
Density @ 293 K: 3.214 g/cm3
Color: green
http://www.chemicalelements.com/elements/f.html
Isotope Half Life
Cl-35
Stable
Cl-36
301000.0 years
Cl-37
Stable
Cl-38
37.2 minutes
Facts
Date of Discovery: 1774
Discoverer: Carl Wilhelm Scheele
Name Origin: From the Greek word khlôros (green)
Uses: Water purification, bleaches http://www.chemicalelements.com/elements/f.html
Obtained From: Salt
Number of Energy Levels: 4
First Energy Level: 2
Second Energy Level: 8
Third Energy Level: 18
Fourth Energy Level: 7
Atomic Mass: 79.904 amu
Melting Point: -7.2 °C (265.95 °K, 19.04 °F)
Boiling Point: 58.78 °C (331.93 °K, 137.804 °F)
Number of Protons/Electrons: 35
Number of Neutrons: 45
Classification: Halogen
Name: Bromine
Crystal Structure: Orthorhombic
Symbol: Br
3
Density @ 293 K: 3.119 g/cm
Atomic Number: 35
Color: Red
Isotope
Half Life
Br-76 16.0 hours
Br-77 2.4 days
Facts
Date of Discovery: 1826
Discoverer: Antoine J. Balard
Name Origin: From the Greek
word brômos (stench)
Uses: Poisonous
Obtained From: Sea Water
Br-79 Stable
Br-80 17.7
minutes
4.42 hours
Br80m
Br-81 Stable
Br-82 1.5 days
Br-83 2.4 hours
Br-84 31.8
minutes
Br-85 2.9
minutes
Number of Energy Levels: 5
http://www.chemicalelements.com/elements/i.html
Basic Information
First Energy Level: 2
Second Energy Level: 8
Third Energy Level: 18
Fourth Energy Level: 18
Fifth Energy Level: 7
Name: Iodine
Symbol: I
Atomic Number: 53
Atomic Mass: 126.90447 amu
Melting Point: 113.5 °C (386.65 °K, 236.3 °F)
Boiling Point: 184.0 °C (457.15 °K, 363.2 °F)
Number of Protons/Electrons: 53
Number of Neutrons: 74
Classification: Halogen
Crystal Structure: Orthorhombic
Density @ 293 K: 4.93 g/cm3
Color: blackish
Facts
Date of Discovery: 1811
Discoverer: Bernard Courtois
Name Origin: From the Greek word iôdes (violet)
Uses: required in humans
Obtained From: sodium and potassium compounds
Isotopes
Isotope/ Half Life
I-122 - 3.6 minutes
I-123 - 13.2 hours
I-124 - 4.2 days
I-125 - 60.1 days
I-126 - 13.0 days
I-127 - Stable
I-128 - 25.0 minutes
I-129 - 1.57E7 years
Isotopes ..cont…
Isotope/ Half Life
I-130 - 12.4 hours
I-131 - 8.0 days
I-132 - 2.3 hours
I-133 - 20.8 hours
I-134 - 52.6 minutes
I-135 - 6.6 hours
I-136 - 1.4 minutes
http://www.chemicalelements.com/elements/i.html
Name: Astatine
Symbol: At
Atomic Number: 85
Atomic Mass: (210.0) amu
Melting Point: 302.0 °C (575.15 °K, 575.6 °F)
Boiling Point: 337.0 °C (610.15 °K, 638.6 °F)
Number of Protons/Electrons: 85
Number of Neutrons: 125
Number of Energy Levels: 6
Classification: Halogen
Crystal Structure: Unknown
First Energy Level: 2
Density @ 293 K: Unknown
Second Energy Level: 8
Color: Unknown
Third Energy Level: 18
Fourth Energy Level: 32
Fifth Energy Level: 18
Sixth Energy Level: 7
Isotopes
Isotope
Half Life
29.4 minutes
At206
1.6 hours
At208
At-211 7.2 hours
At215
At217
At218
At219
0.1 milliseconds
32.0
milliseconds
1.6 seconds
50.0 seconds
Facts
Date of Discovery: 1940
Discoverer: D.R. Corson
Name Origin: From the Greek
word astatos (unstable)
Uses: No uses known
Obtained From: Man-made
Trends across a period
The metallic properties of the elements decrease from
left to right in the PT.
The elements at´ the left have low ionization energy so
they form + ions that form ionic compounds with
negative ions.
The elements at the right form either ionic compounds
with metals or covalent compounds with nonmetals.
Cont…Trends across a period
The oxides of metals are ionic and if you dissolve them
in water, they form basic solutions:
Na2O(aq) + H2O(l)  2NaOH(aq)
The oxides of non metals, towards the middle of thePT,
are covalent and in water form acid solutions:
SO3(g) + H2O(l)  H2SO4(aq)
CO2(g) + H2O(l) H2CO3(aq)  H+(aq) + HCO3-(aq)
The chlorides of metals are ionic and dissolve in water
to dissociate in the metal positve ion and the halogen
negative ion (halide). The solutions are neutral:
NaCl(aq) H2O(l)  Na+(aq) + Cl-(aq)
Towards the middle of the table, the chlorides dissolve
in water to give acidic solutions:
SiCl4(aq) + 2 H2O(l)  SiO2 + 4H+ + 4Cl-