Chemistry Chapter 4:
The Periodic Table
Section 4: FromWhere Did the
Elements Come?
Key Terms
Nuclear reaction – reaction that
affects atomic nucleus
 Superheavy element – an
element with an atomic # > 106
 Transmutation – changing from
one element to another

Key Terms 2
– Enstein’s quantitative
description of the mass energyrelationship
 Here e, m and c are energy, mass
& the speed of light, respectively.
2
 E=mc
Key Terms 3
Supernova – explosion of stars more
than 100x more massive than the sun
 The blast is caused by conversion of
core H & He into elements up to Fe.
 During the explosion, this change
yields collapse & formation of elements with higher atomic # than Fe.

Key Terms 4
Synthetic elements – created by
chemists using particle accelerators,
these elements do not occur naturally
and have atomic # > 92.
 Cyclotron – charged particle accelerator 1st invented by the American scientist E.O. Lawrence in 1930

Key Terms 5
Synchrotron – used to create
superheavy elements
 This device accelerates a few types
of charged particles past 1/10th the
speed of light, c.
 One tenth c is the top speed that
cyclotrons can yield.

Things To Know/Answer
How do the naturally occurring
elements form?
 How does a transmutation change
one element into another?
 How are particle accelerators used
to create synthetic elements?

Natural Elements
Only 93 of the elements in the
periodic table are found in nature.
 Technetium,Tc; promethium, Pm,
& neptunium, Np, are found in
the spectra of stars.
 C, H, O, N, P & S are most of the
atoms in living things.

Natural Elements 2
Popular theory – common and natural
elements were created in the centers
of stars billions of years ago, shortly
after the “Big Bang”
 H & He formed after the Big Bang
through cooling of temperatures.

Natural Elements 3
Here, energy was able to become
subatomic particles.
 These formed H & He in clouds that
gravity centralized.
 The cloud gathering yielded great
solar density which caused rising
central temperature & pressure.

Natural Elements 4
Nuclear reactions started in these
solar centers.
 Stars have fusion reactions where
4H become 1He with an apparent
loss of mass that becomes energy.
 E=mc2 describes this change.

Natural Elements 5
Other elements can form by
fusion. See Figure 28 on pg. 144.
 See www.scilinks.org Origin of
Elements under code HW4093.

Transmutations
Middle Ages = alchemists trying
to turn Pb into Au via ordinary or
non nuclear chemical reactions.
 Were they successful? See
Alchemy at code HW4006.

Transmutations 2
Rutherford saw particle tracks in
his experiments.
 He reasoned that they came from
disintegration of atomic nuclei
after being struck by α-particles.

Transmutations 3
W.D. Harkins, an American, &
P.M.S. Blackett confirmed that Y
shaped tracks meant transmutation
 This was b/c N disintegrated into O
and a proton when struck by an αparticle.

Synthetic Elements
Researchers hopped on the
transmuting train & synthesized
elements that were not available
in nature w/ particle accelerators.
 Cyclotrons & Synchrotrons use
successive pulses of energy to
speed up charged particles.

Synthetic Elements 2
They make particles collide at
high speed and energy, fuse, and
form heavier elements.
 Greater speed yields greater mass
and more difficulty continuing
acceleration

Synthetic Elements 3
The charge particles must reach
successive pulses on time.
 If not, they slow down, lose energy
and fail to fuse.
 Most superheavy elements last for a
small fraction of a s except for 114.

Synthetic Elements 4
The only time scientists synthesized element 114, it lasted for
30s then decayed to 112. Why is
this problematic?
 Russian scientists bombarded Pu214 with Ca-40 for 40 days to
create 114.

Synthetic Elements 5

Many researchers view element
114 as the beginning of a stable
set of synthetic elements. Why?