Formation of Elements

• This study guide covers the formation of elements and related key terms

Key Terms

• Nuclear Reactions
• Fusion
• Fission
• Isotopes
• Atoms
• Protons
• Neutrons
• Electrons
• Nucleosynthesis
• Big Bang
• Stellar
• Supernova

Definition of Terms

• Nucleosynthesis refers to the creation of new atomic nuclei that are made of protons and neutrons, and ultimately, the formation of elements.
• Nuclear Reactions are chemical occurrences involving the nuclei of atoms
• Fusion is the process or result of joining two or more entities into a single one.
• Fission is the action of splitting something into two or more parts.
• Atomic Number indicates the number of protons in the nucleus
• Mass Number represents the total number of protons and neutrons in the nucleus.
• Mass Number is represented by A.
• Atomic Number is represented by Z.

Big Bang Theory

• Big Bang theory is the accepted scientific explanation for the origin of the universe, supported by multiple lines of evidence.
• It is a popular attempt to describe the early universe
• The theory was first proposed by Belgian astrophysicist and priest Abbé Georges Lemaître (1894-1966).
• The name Big Bang was coined by British astronomer Fred Hoyle in 1949.
• All matter and energy were compressed at a single point called singularity at the time of the expansion.

Abundance of Elements

• Expanding Universe contains an abundance of light, heavy, and heavier than iron elements.

Major Types of Nucleosynthesis

• Primordial or Big Bang Nucleosynthesis
• Stellar Nucleosynthesis
• Supernova Nucleosynthesis

Primordial Nucleosynthesis or Big Bang Nucleosynthesis

• Protons, neutrons, and electrons were moving around without control.
• Occurring during the first three minutes of the rapid expansion of the universe, rapid cooling slowed down sub-atomic particles.
• Rapid cooling provides more chances for binding together to form light elements.
• Elements include Deuterium, Hydrogen, Helium, Lithium and Beryllium.
• Mass Number = Protons + Neutrons
• Neutrons = Mass Number – Atomic Number
• Atomic Number = Protons = Electrons

Isotopes of Hydrogen

• Isotopes are atoms of the same element with the same number of protons and electrons, but a different number of neutrons.

Deuterium:

• Deuterium (D), an isotope of Hydrogen, as formed from the fusion of a proton and a neutron, accompanied by the emission of a high-energy photon (ɣ ).
• It is a stable element.

Tritium:

• Tritium (T), or Hydrogen-3, was produced from the fusion of two deuterium nuclei and the release of a proton.
• It is an unstable element.

Isotopes Chart

• Lithium-6 has 6 neutrons and is stable
• Lithium-7 has 7 neutrons and is stable
• Lithium-8 has 8 neutrons and is unstable

Stellar Nucleosynthesis

• The process by which elements are created within stars by combining the protons and neutrons together from light elements.
• Stars are giant balls mostly made of hydrogen and helium, and act as sites for nuclear reactions in the universe.
• Stars are able to fuse light elements to form heavier elements such as Boron, Carbon, Nitrogen, up to Iron

Supernova Nucleosynthesis

• The process by which heavier elements than Iron (Fe) were created.
• Heavy elements require extreme temperatures.
• Heavy elements require an abundance of neutrons
• Supernova stars temperature can reach up to 100 Billion °C
• This is 6000x hotter than the core of the sun

Periodic Table

• Dmitri Mendeleev examined the relationship among atomic masses of elements, and their physical and chemical properties.
• He believed that the atomic mass of elements was the most fundamental property in classifying the element.
• He arranged the known elements according to their properties and increasing atomic masses.
• In 1913, Henry Moseley discovered a fundamental property of an element.
• The atomic number is the most fundamental property of an element and not its atomic mass.
• This discovery changed the perspective of elements and their properties.
• Mendeleev's Periodic Law was accordingly modified into the Modern Periodic Law.