To discuss element

origin, lets divide

the elements into

two categories.

1. Naturally Occurring

-made in the center

of stars.

2. Synthetic

-made in the lab

by people

Chemists have identified

93

such elements, three

of which are not

found on Earth.

Tc, Pm, Np are found in the

spectra of stars.

According to

the Big BangTheory,

the universe began with

the explosion of

a single primeval atom.

!

Temperatures were in

the millions of Kelvins.

Matter does not exist at

such temperatures. All

was energy. (E=mc2)

It is believed that the

universe cooled as it

expanded.

Some of the energy was

converted to matter.

(p+, n, e-)

Continued cooling

allowed these subatomic

particles to come

together forming

HYDROGEN.

H

Hydrogen atoms grouped

together and fused in

the heat, forming

helium.

He-4

These reactions

provide E which

serves as fuel for

the sun. This is

how high temps.

are maintained.

HOT!

The higher temp. allows

He to fuse, creating

heavier elements like

C, N, O, Fe and Ni.

When a star uses

up the H and He

it collapses,

becoming a...

Atoms are torn apart

during formation of the

red giant.

p+ n

These stray particles are

taken up by other nuclei,

forming elements heavier

than Fe and Ni.

The star will eventually

explode as a...

spreading

matter across

millions of

kilometers.

This is how we believe

the Earth was “seeded”

with elements.

Natural elements were

formed by nuclear

reactions that occurred

in the sun.

…a change in the

composition of the

nucleus of an atom

Synthetics-White Letters

Synthetic elements are

made from a

transmutation.

…the process of changing

one nucleus into another

by radioactive disintegration

or bombardment with

other particles.

Early in the century,

scientists were studying

the tracks made by alpha

particles through

water vapor in

cloud chambers

Harkins

& Blackett

Photos…

Page 146

Figure 4-33

Alpha +

Nitrogen

collision

H

O

4

2 He + 14

7 N

17

8 O + 1

1 H

Oxygen formation

Transmutation reactions

soon began to be studied

in cyclotrons, or particle

accelerators.

2 “D”

Shaped

Magnets

With a

Gap.

In a cyclotron, ions are

accelerated and collide with

a target nuclei to create an

element with a much higher

atomic number.

Problem: Heavier elements

accelerate more slowly.

A synchroton can get particles

to hit head-on creating more

energy. This allows creation

of the “superheavies.”

--cheaper than

a cyclotron

Particles are given “a push” now

and then as they go around this

facility.

Have an atomic number

greater than 106.

Many of these elements

only last for a few

thousands of a second.

. …because we can

…to learn about

nuclear structure

Some elements are given

a 3 letter abbrev. until

a name is decided.

Do you recognize any

of the names?