Physical Science

• The universe is composed of 73% Hydrogen and 25% Helium, with 2% for others.
• Nuclear reaction is the birth, life, and death of the stars.
• The universe is 13.7 billion years old.
• The oldest elements/particles in the universe are Hydrogen and Helium, which are the lightest elements.
• The stages of the Big Bang theory include Singularity, Inflation, and Nucleosynthesis.
• Singularity is a space moment where the universe was infinitely hot and dense, with a temperature of negative 36 per second.
• Inflation is an exponential expansion of space in the early universe, which resulted in the lumalawak ang area of the universe.
• Nucleosynthesis creates new atomic nuclei from pre-existing nucleons, primarily protons and neutrons.
• Nucleo- nucleus
• Synthesis- putting together
• 1proton+1neutron= hydrogen
• hydrogen has 3 isotopes
• Isotopes are same element that differ in the number of neutrons (differ in mass number).
• • Aristotle: Supported the Pythagorean view and added the four elements, stating that all matter is infinitely invisible
  • Leucippus of Miletus (500-420 B.C.): Believed that all matter, including the four elements, was composed of a basic building block called the atom
• Ancient Ideas of the Atom:

  • Thales of Miletus (640-546 B.C.): Water was the primary component of all matter
  • Anaximenes (526 B.C.): Air was the primary component
  • Heraclitus (535-475 B.C.): Fire was the primary component
  • Pythagoras of Samos (582-507 B.C.): Proposed that all matter is a combination of water, air, fire, and earth
  • Empedocles (450 B.C.): Developed the theory that all matter in the universe was composed of various combinations and proportions of four elementary substances
• Atom:

  • Atom comes from the Greek word "atomos," meaning indivisible
  • Democritus of Abdere (460-370 B.C.) proposed the characteristics of atoms:

  1. Indivisible because it is extremely small

  2. Solid, spherical, not empty

  3. Surrounded by an empty space

  4. Eternal because atoms are seamless

  5. Immeasurable number of shapes
• Epicurus (341-270 BC):

  • Supported Democritus's atomos theory, stating that belief in such theory can help human beings live better lives
• Alchemy:

  • Atomism, widely attributed to Democritus, is the theory that all matter is made up of atoms
  • Refuted by Aristotle as it was not in line with his idea on natural phenomena, leading to it not being explored for the next 2000 years
• The Atom:

  • Three subatomic particles: protons, neutrons, and electrons
  • Protons have a positive charge, electrons have a negative charge, and neutrons do not have a charge
  • Particles with the same charge are repulsed, while particles with opposite charges are attracted
  • The nucleus of an atom is made up of protons and neutrons, with the number of protons determining the atomic number
  • Protons are the same in an element, while the number of neutrons may vary, determining the isotope of an atom
• • Electrons are negatively charged and are attracted to the positively charged protons in the nucleus
  • An atom is electrically neutral if it has an equal number of protons and electrons, and if they differ, it is called an ion
• Sub-particles of an atom:

  • Protons, neutrons, and electrons
  • Protons: Positively charged
  • Neutrons: No charge
  • Electrons: Negatively charged
• 600 million tons of hydrogen in the sun is being converted into helium every second
• The sun is 4.5 billion years old and will become a red giant star when it reaches 10 billion years of existence
• When the sun becomes a red giant star, it will produce heavier elements up to iron
• By the 11 billionth year, the sun will implode and become a supernova
• A giant cloud of gas and dust known as a nebula is formed
• A protostar is formed from a nebula due to gravity pulling hydrogen gas together until it spins faster and faster and becomes ignited
• A main sequence star starts to form when nuclear fusion occurs at the core of the star, causing it to contract, glow, and become stable. Hydrogen is converted into helium
• When a star runs out of hydrogen in its core, it is unable to generate heat, leading to its contraction and expansion. The star cools down, glows red, and the helium fuses into carbon, turning the star into a red giant
• A red giant star becomes exhausted of nuclear fuel, and the outer material is blown off into space, leaving behind inert carbon. The remnant is known as a white dwarf
• The white dwarf cools down and no longer emits light and heat, becoming a hypothetical black dwarf
• A neutron star is believed to be formed from a supernova explosion, which is also the smallest star
• A black hole is a region in space where gravity is too strong for any matter to escape from it
• A more massive main sequence star evolves, cools, and expands faster than a low-mass star, turning into a red supergiant star. Carbon fusion still occurs, and oxygen is formed
• Supernova is what happens when a star reaches the end of its life and explodes in a brilliant burst of light. Supernovas can briefly outshine entire galaxies and radiate more energy than our sun will in its entire lifetime. They are also the primary source of heavy elements in the universe
• Stellar formation and evolution formed the elements heavier than beryllium (Be) up to iron (Fe)
• Big Bang Nucleosynthesis formed the light elements: hydrogen (H), helium (He), and lithium (Li)
• Stellar explosion, or supernova, formed the elements heavier than iron (Fe)
• Helium is the building block of every element except for hydrogen
• Stars end up nuclear reactions at element iron