1. Chemistry Chapter 4: The Periodic Table
Section 4: FromWhere Did the Elements Come?

2. Key Terms Nuclear reaction – reaction that affects atomic nucleus
Superheavy element – an element with an atomic # > 106
Transmutation – changing from one element to another

3. Key Terms 2
E=mc2 – Enstein’s quantitative description of the mass energy-relationship
Here e, m and c are energy, mass & the speed of light, respectively.

4. 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 ele-ments with higher atomic # than Fe.

5. Key Terms 4
Synthetic elements – created by chemists using particle accelerators, these elements do not occur naturally and have atomic # > 92.
Cyclotron – charged particle acceler-ator 1st invented by the American sci-entist E.O. Lawrence in 1930

6. 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.

7. 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?

8. 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.

9. 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.

10. 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.

11. 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.

12. Natural Elements 5
Other elements can form by fusion. See Figure 28 on pg. 144.
See Origin of Elements under code HW4093.

13. 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.

14. 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.

15. 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 α-particle.

16. 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.

17. 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

18. 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.

19. Synthetic Elements 4
The only time scientists synthe-sized element 114, it lasted for 30s then decayed to Why is this problematic?
Russian scientists bombarded Pu-214 with Ca-40 for 40 days to create 114.

20. Synthetic Elements 5
Many researchers view element 114 as the beginning of a stable set of synthetic elements. Why?