Stellar Nucleosynthesis and Atomic Number

A giant cloud of gas and dust that acts as the birthplace of stars.

A star that fuses hydrogen into helium in its core, producing energy and light. This is the main phase in a star's life.

A process where hydrogen is converted into helium using carbon, nitrogen, and oxygen as catalysts. This occurs in massive stars.

A star that has exhausted its hydrogen fuel and is fusing helium into carbon in its core, leading to a cooler and larger star.

A very large and luminous star that has evolved beyond the red giant stage, fusing heavier elements in its core. This is a sign that it's entering the final stages of its life.

The theory that the universe began with the explosion of a single, extremely hot and dense point, called a singularity.

The process that occurred after the Big Bang, where the first elements like Hydrogen, Helium, Lithium, and Beryllium were formed.

The process that creates new atomic nuclei from existing protons and neutrons. It occurs within stars through nuclear fusion.

The process that produces energy in stars by combining light atomic nuclei into heavier ones. For example, the fusion of Hydrogen into Helium.

The life cycle of a star, starting from its formation from a cloud of gas and dust to its eventual death, depending on its size and mass.

Elements, like Hydrogen and Helium, formed during Big Bang Nucleosynthesis and were present from the beginning of the universe.

Elements formed during the different stages of a star's life cycle through nuclear fusion.

The process of a star's core collapsing under its own gravity, resulting in a powerful explosion and the creation of heavy elements.

The process by which elements heavier than iron are formed through the capture of neutrons in a seed nucleus. This process is divided into two types: slow neutron capture (s-process) and rapid neutron capture (r-process).

A slow process where a neutron is captured by the nucleus, followed by a radioactive decay. This process builds up heavier elements slowly.

A rapid process where a neutron is captured very quickly by the nucleus before it can decay. This results in the formation of heavier elements quickly.

A type of emission nebula that glows with colors due to the ionized gas that it contains. It often forms as a result of a red giant star losing its outer layers in the late stages of its life.

A dense, small star formed from the core of a collapsed red giant star. It is made up mostly of carbon and is no longer undergoing nuclear fusion.

A very compact and dense star formed from the supernova collapse of a massive star. It is the smallest type of star and is made up mainly of neutrons.

Empedocles proposed that all matter is composed of four elemental substances: earth, air, fire, and water. He believed these elements combined in different proportions to create everything in the universe.

Democritus proposed that all matter is made up of tiny, indivisible particles called atoms. He believed atoms were solid, indestructible particles that existed in different shapes and sizes.

Joseph Proust's Law of Definite Proportions states that a chemical compound always contains the same elements in the same proportion by mass, regardless of its source.

John Dalton's Atomic Theory states that all matter is composed of atoms, which are indivisible and indestructible. Atoms of a given element are identical in size and mass. Compounds are formed by the combination of atoms in fixed ratios.

Wilhelm Rontgen discovered X-rays, a form of electromagnetic radiation that can penetrate matter and create images of bones and internal organs.

Joseph John Thomson discovered the electron, a negatively charged subatomic particle, through his experiments with cathode ray tubes. He proposed the "plum pudding model", where electrons are embedded in a positively charged sphere.

Robert Millikan determined the charge of an electron through his oil drop experiment. This experiment involved measuring the force on charged oil droplets suspended in an electric field.

Ernest Rutherford discovered the nucleus, the positively charged center of an atom, through his gold foil experiment. He found that alpha particles were deflected by a small, dense, positively charged region within the atom.

Bohr's planetary model proposed that electrons orbit the nucleus in specific, fixed energy levels, like planets around a star. This was a major advancement in atomic theory, suggesting a more structured model than the previous electron cloud concept.

Henry Moseley, an English physicist, used x-ray spectroscopy to determine the atomic number of an element. This discovery was groundbreaking because it established the atomic number as the fundamental identifier of an element, not its atomic weight.

Nuclear transmutation is a process where one type of atom is changed into another. Rutherford accomplished this by bombarding atoms, which made them change into different elements. The first nuclide he synthesized was an isotope of Oxygen-17.

James Chadwick, a British physicist, discovered the neutron in 1932. This discovery was significant because it explained the existence of isotopes, atoms of the same element with different masses.

Technetium (Tc) was the first synthetic element, created by Emilio Segre and Carlo Perrier in 1937 by bombarding molybdenum with deuterons (heavy hydrogen). This opened a new era of element synthesis in labs.

Astatine (At), element 85, was synthesized in 1940 by Corson, Mackenzie, and Segre. They bombarded bismuth with alpha particles, forcing it to change into astatine.

In 1942, at the University of Chicago, the first controlled nuclear chain reaction was achieved in a reactor. This landmark event laid the foundation for nuclear energy and technology.

Promethium (Pm) was identified as a byproduct of uranium fission, while Francium (Fr) was discovered as a breakdown product of uranium. These discoveries further expanded our knowledge of radioactive decay and its applications.

Aristotle suggested that matter is continuous, meaning it can be divided endlessly into smaller and smaller pieces. He believed that there was no fundamental building block for matter.

The Law of Definite Proportions states that elements combine in fixed proportions by mass regardless of the source of the compound. For example, water always has two hydrogen atoms and one oxygen atom, even if it comes from different sources.

Dalton's Atomic Theory is a cornerstone of modern chemistry. It proposes that all matter is composed of tiny, indivisible particles called atoms. Atoms of the same element are identical, while atoms of different elements have different masses. Atoms cannot be created or destroyed, but they can be rearranged in chemical reactions.

Mendeleev arranged the known elements in a periodic table based on their atomic mass. The table showed a periodic pattern in their physical and chemical properties, like luster and reactivity. This arrangement was later known as the periodic law.

Radioactivity is the spontaneous breakdown of an atom's nucleus, releasing energy and particles. This discovery by Becquerel and Curie challenged the idea that atoms were indivisible and led to the development of nuclear physics.

Roentgen discovered X-rays, which are a form of electromagnetic radiation with high energy. X-rays can penetrate many materials and are used in medical imaging and other applications.

Thomson's experiments with cathode-ray tubes led to the discovery of electrons, negatively charged subatomic particles. This discovery contradicted Dalton's idea of indivisible atoms and changed our understanding of atomic structure.

Thomson's proposed model depicted the atom as a positively charged sphere with negatively charged electrons embedded in it, like plums in a pudding. It was later proven incorrect, but it was a significant step towards understanding atomic structure.

Millikan's Oil Drop Experiment precisely measured the charge of an electron. This measurement was crucial in understanding the fundamental nature of electricity and the structure of matter.

Rutherford's Gold Foil Experiment revealed that atoms have a small, dense, positively charged nucleus at the center, surrounded by a mostly empty space where electrons orbit. This model replaced Thomson's Plum Pudding Model and revolutionized our understanding of atomic structure.