Elements and Nuclear Reactions: A Deep Dive

Nuclear Fission

By bombarding uranium atoms with neutrons, the nuclei are broken. This break, called nuclear fission, releases large amounts of energy. This process also releases more neutrons, which can break more uranium nuclei, creating a continuous chain reaction.

Nuclear Power Plants

The heat released in nuclear fission is enormous. However, to harness this energy, the chain reaction must be controlled. This is done in nuclear power plants. Nuclear power generation has risks, such as accidents like Chernobyl, and the generation of radioactive waste.

Nuclear Fusion

This occurs when small nuclei join to form larger nuclei, releasing a large amount of energy. The fuel used is hydrogen, abundant in seas and oceans. Nuclear fusion is cleaner than fission, producing less radioactive waste. The main drawback is the need for specialized, experimental facilities.

Elements in Nature

Ninety naturally occurring elements exist. The rest are created in laboratories and are called artificial elements.

Elements on Earth

The most abundant element on Earth is iron. In the Earth’s crust, oxygen and silicon are the most abundant.

Elements in Living Things

Six elements constitute 99% of living matter: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. The remaining 1% are trace elements like fluorine.

Periodic Table of the Elements

In 1869, Mendeleev published a table arranging the 63 known elements in rows and columns. He left spaces for undiscovered elements, which were later found.

Atomic Mass and Radioisotopes

The mass of atoms is very small. The atomic mass unit (u) is used as a standard. The relative atomic mass (Ar) of an element is the weighted average of the masses of its naturally occurring isotopes.

Some isotopes, called radioisotopes, exhibit radioactivity because their nuclei are unstable and disintegrate. Types of radiation include:

  • Alpha-radiation: Helium nuclei (two protons and two neutrons).
  • Beta-radiation: High-speed electrons.
  • Gamma-radiation: Similar to light or X-rays but with much more energy.

Radiation, especially gamma, is harmful to health. Half-life is the time it takes for half of the initial radioisotope nuclei to decay. A longer half-life indicates greater stability.

Radioisotopes in Medicine

Diagnosis: A solution with radioisotopes is injected into the patient, and a special X-ray detects gamma rays to image the body.

Cancer treatment: Small doses of radiation target cancerous tissues to destroy cancer cells.

Carbon-14 Dating

Carbon-14, a radioisotope of carbon, is continuously generated in the atmosphere. All living things contain C-14. Analyzing the remaining C-14 allows scientists to determine the age of organic samples.

Elements in the Universe

The most abundant elements in the universe are hydrogen and helium.