Regions of the Table
metals: left side of Table; form cations
properties:
lustrous
(shiny)
ductile
(can pull
into wire)
good conductors
(heat and electricity)
malleable
(can hammer
into shape)
-- Because of their low ionization energies, they are
often oxidized in reactions. (i.e., they lose e–)
-- Metallic character of the elements increases as
we go down-and-to-the-left.
Regions of the Table (cont.)
nonmetals: right side of Table; form anions
properties: good insulators; gases or brittle solids
neon
Ne
sulfur
S8
iodine
I2
-- memorize the HOBrFINCl twins
(or…Hans and Franz, the ClOBrHIFN twins)
“Wer sind sie?”
“Die ClOBrHIFN Zwillinge!”
bromine
Br2
Regions of the Table (cont.)
metalloids (semimetals): “stair” between metals
and nonmetals (B, Si, Ge, As, Sb, Te, Po, At)
metals
Si
and
Ge
computer chips
properties: in-between those of metals
and nonmetals; “semiconductors”
Si and Ge
computer chips
(i.e., a
“basic”
oxide)
Reactivity Trends
metal oxide + water
MgO(s) + H2O(l)
metal oxide + acid
CaO(s) + 2 HNO3(aq)
metal + nonmetal
2 Al(s) + 3 Br2(l)
metal hydroxide
Mg(OH)2(aq)
salt + water
Ca(NO3)2(aq) + H2O(l)
salt
2 AlBr3(s)
(i.e., an
“acidic”
oxide)
Reactivity Trends (cont.)
nonmetal oxide + water
CO2(g) + H2O(l)
nonmetal oxide + base
CO2(g) + 2 KOH(aq)
acid
H2CO3(aq)
salt + water
K2CO3(aq) + H2O(l)
Group Trends
Alkali Metals
-- the most reactive metals (one e– to lose)
-- obtained by electrolysis
of a molten salt
e.g., chloride ion is oxidized
and sodium ion
is reduced
2 NaCl(l)
2 Na(l) + Cl2(g)
-- react with hydrogen to form metal hydrides:
2 M(s) + H2(g)
2 MH(s)
-- react with water to form metal hydroxides:
2 M(s) + 2 H2O(l)
2 MOH(aq) + H2(g)
-- react w/O2: Li yields Li2O, others
yield (mostly) peroxides (M2O2)
2 M(s) + O2(g)
M2O2(s)
Potassium in water, forming flammable hydrogen
and soluble potassium hydroxide.
Alkaline-Earths
-- not as reactive as alkalis (two e– to lose)
compared to alkalis: harder, denser, higher MPs
-- Ca and heavier ones react w/H2O to form
metal hydroxides
Ca(s) + 2 H2O(l)
-- MgO is a
protective
oxide coating
around
substrate Mg
Ca(OH)2(aq) + H2(g)
Mg ribbon
MgO
Hydrogen
-- a nonmetal, but belongs to no family
-- reacts w/other nonmetals to form
molecular (i.e., covalent) compounds
The Hindenburg
(She
burned
up in
(She
was
scuttled
in May
1937,
June
1919,
along
withkilling
71 other
36
passengers.)
German
ships.)
Halogens
-- At isn’t considered to be a
halogen; little is known about it
-- at 25oC, F2 and Cl2 are gases,
Br2 is a liquid, I2 is a solid
-- their exo. reactivity is dominated
by their tendency to gain e–
-- Cl2 is added to water; the HOCl
produced acts as a disinfectant
-- HF(aq) = weak acid;
HCl(aq)
HBr(aq) = strong acids
HI(aq)
A small amount of a
halogen is mixed with a
noble gas to fill halogen
lamps. The halogen sets
up an equilibrium with
the tungsten filament
to prevent the heated
tungsten from being
deposited on the
inside of the bulb.
Noble Gases
-- all are monatomic; have
completely-filled
s and p orbitals
-- He, Ne, and Ar have no known
compounds; Rn is radioactive
-- Kr has one known compoud (KrF2);
Xe has a few (XeF2, XeF4, XeF6)
professional-grade
Rn detector
Fan for
Rn mitigation
Ionic Radius
smaller than parent atoms;
Cations are _______
larger than parent atoms.
anions are ______
Ca atom
20 p+
20 e–
Ca2+ ion
20 p+
18 e–
Cl atom
17 p+
17 e–
Cl– ion
17 p+
18 e–
Ca
Ca2+
Cl
Cl–
EX. Compare the sizes of Fe,
Fe2+, and Fe3+.
Then compare Br with
Br–.
Fe > Fe2+ > Fe3+
Br– > Br
Electronegativity
electronegativity: the tendency for
a bonded atom to
attract e– to itself
Electronegativity increases going...
up and to-the-right.
Linus Pauling
quantified the
electronegativity
scale.
Most electronegative element is... fluorine (F).
“Oh, man… I forgot which ones the
most electronegative elements are.”
F = 4.0
O = 3.5
N = Cl = 3.0
“Shee-oot…
Ow teh ye…
FO’ NCl.”
Others: C = 2.5 H = 2.1