Physical Science Reviewer PDF

**PHYSICAL SCIENCE REVIEWER** **LESSON 1: FORMATION OF ELEMENTS** **ATOM** - Smallest unit that makes up all matter. **ELEMENT** - A pure substance that represent the species (variety) of a specific atom. **ISOTOPES** - Atoms of the same element but with diff atomic mass. (different number of ne...

**PHYSICAL SCIENCE REVIEWER** **LESSON 1: FORMATION OF ELEMENTS** **ATOM** - Smallest unit that makes up all matter. **ELEMENT** - A pure substance that represent the species (variety) of a specific atom. **ISOTOPES** - Atoms of the same element but with diff atomic mass. (different number of neutron) **PROTON** - Positively charge sub-atomic particle **ELECTRON** - Negatively charge sub-atomic particle **NEUTRON** - Uncharged particle **THE BIGBANG THEORY** - Scientists believe that the formation of the universe began through the explosion of a primordial atom which happened 13 billion years ago. Georges Lemaitre **EVIDENCES OF THE BIG BANG** - Cosmic expansion, Edwin Hubble - Cosmic Microwave Background, George Gamow. (RELIC RADIATION) - Primordial or Big Bang Nucleosynthesis **NUCLEOSYNTHESIS** ➤ is the formation of atomic nuclei. ➤ Started as a quarks forming the proton and neutrons. **THREE TYPES OF NUCLEOSYNTHESIS** 1. BIGBANG NUCLEOSYNTHESIS 2. STELLAR NUCLEOSYNTHESIS 3. SUPERNOVA NUCLEOSYNTHESIS **LIFE CYCLE OF A STAR** ➤ stars must have energy to exist for a certain length of time. ➤ energy comes from various nuclear fusion reactions between light elements, involving the release of a huge amount of energy that keeps the star hot ➤ Atoms collide and alters atomic structures and releases an enormous quantity of energy ➤ the energy release is manifested as the light emitted by the stars. ➤ at the core of the star, the hydrogen is converted to helium through the process of nuclear fusion. As stars age they run out of fuel massive stars undergo supernova (explosion of a star) The explosion results to the formation of elements heavier than iron **BIGBANG NUCLEOSYNTHESIS** ➤ Formation of light elements, Hydrogen and Helium by combination of protons and neutrons right after the Big Bang. ➤ Other light element, Lithium was also formed through this type of nucleosynthesis **STELLAR NUCLEOSYNTHESIS** Formation of elements in the stars interior. Occurs through nuclear fusion and electron capture Responsible for the formation of elements heavier than Helium, He until Iron, Fe. Formation of Hydrogen to Helium Proton-proton Chain or Hydrogen Burning- fusion of four hydrogen nuclei to form a helium nucleus. **FORMATION OF HYDROGEN TO HELIUM** **Proton-proton Chain or Hydrogen Burning**- fusion of four hydrogen nuclei to form a helium nucleus. **Carbon, Nitrogen, Oxygen (CNO) Cycle**- conversion of hydrogen to helium among massive stars by using carbon as catalyst **WHAT HAPPENS ONCE A STAR HAS USED UP THE HYDROGEN IN ITS CORE?** P-P chain and CNO Cycle stop Helium starts to be expended and burned Helium is burned to produce Carbon through the process called Tri-alpha process. **TRI-ALPHA PROCESS** Alpha particle is equivalent to Helium atom First reaction forms unstable Beryllium, Be atom **ALPHA LADDER PROCESS** ➤ additional helium burning reactions results to synthesis or formation of heavier nuclei up to iron, Fe **HOW DO ELEMENTS HEAVIER THAN IRON FORM?** **Supernova Nucleosynthesis** is believed to be the reason for \* the formation of heavier nuclei after Iron. ➤ The pathway for heavier nuclei to be formed is through neutron capture; not nuclear fusion. ➤ Neutron capture happens when a neutron is added to a seed nucleus. **Neutron capture** ➤ Creates a heavier isotopes of the same element ➤ Making it stable or radioactive ➤ Radioactive are unstable nuclei undergo radioactive decay (i.e. beta decay) ➤ Electron is emitted; atomic number of the nucleus to increase by one, becoming an isotope of the element **Two types of Neutron capture:** ➤ **S-process (slow)**, addition of neutron is so slow that beta decay happened before another neutron is added to the nucleus. ➤ **R-process (rapid)**, fast capture of neutron before radioactive decay occurs. **Astro chemists** are part Astronomers and part Chemists. They intensely study the periodic table but within the context of space rather than of Earth. As an Astrochemist, you don't only observe stars, but you also examine, analyze, and dissect them. Astrochemists take a much closer look and study the different aspects of all the fascinating objects in the universe on a molecular level in hopes to answer questions how they were formed. **LESSON 2: FORMATION OF ELEMENTS IN THE LABORATORY** **ATOM -** Is the smallest unit of all matter. HISTORY: **Thales of Miletus** -- water constituted all matter **Empedocles** - Air, water, earth, and fire as the four essential elements as sources of all matter **Leucippus** - A material will reach a point that it can never be divided (Leucippus) ATOMOS **Democritus** - Materials are composed of tiny, solid, indivisible, and indestructible atoms (Democritus) **ARISTOTLE** - Water, air, fire, and earth were the fundamental elements; concept of ether. **ALCHEMY** - Idea of changing the nature of a substance to form a new one. - In 1669 German merchant and amateur alchemist Hennig Brand attempted to created a Philosopher's Stone; an object that supposedly could turn metals into pure gold. He heated residues from boiled urine, and a liquid dropped out and burst into flames.. This was the first discovery of Phosphorus - In 1680 Robert Boyle also discovered phosphorus, and it became public. - In 1809 at least 47 elements were discovered, and scientists began to see patterns in the characteristics. - In 1863 English chemist John Newland, divided then discovered 56 elements into 11 groups, based on Characteristics. Dmitri Mendeleev - arranged the elements in order of increasing relative atomic mass Henry Moseley - noticed that when x-rays were shot to sample elements, the frequencies measured were much to elements with higher number of protons; element's identity is uniquely determined by the number of protons it has X-RAY SPECTROSCOPY. - Is a technique that detects and measures photons, or particle of light, that have wavelengths in the X-ray portion of the electromagnetic spectrum. It's used to help scientists understand the chemical and elemental properties of an object. Key to the Periodic Table Elements are organized on the table according to their atomic number. **Atomic Number -** This refers to how many protons an atom of that element has. - Number of protons = atomic number **Atomic Mass -** It is derived at by adding the number of protons with the number of neutrons. - Atomic mass = protons + neutrons. **NUCLEAR REACTION** - Change in the identity or characteristics of an atomic nucleus, induced by bombarding it with an energetic particle. The bombarding particle may be an alpha particle, a gamma ray photon, a neutron, a proton, or a heavy ion. **Nuclear Transmutation Reaction -** involves the transformation of one element or isotope into another element. First carried out by E. Rutherford. TRANSMUTATION James Chadwick discovered neutron when a neutral particle was produced along with Carbon-12 by the nuclear reaction between Be-9 and He-4 **DISCOVERY OF NUCLEAR TRANSMUTATION** - The first synthesized element that does not occur naturally on earth was Technetium - Bombardment of molybdenum by deuterons (heavy hydrogen). **DISCOVERY OF THE MISSING ELEMENTS** - 1925: missing elements in the periodic table, 43, 61, 85, and 87. - Two of the four were synthesized in the laboratory using particle accelerator (device that speeds up proton to overcome the repulsion of positive charges involved.) - 85^th^ element: bombardment of bismuth (Bi is 83^rd^ element and fast moving alpha particle using CYCLOTRON ) - 85^th^ element is called astatine, At; Gr. "astatos" meaning Unstable. - 61^st^ element, Promethium: discovered as a decay product of fission of uranium - 87^th^ element, Francium: discovered as a breakdown product of actinium; synthetically can be produced by bombarding thorium with protons or by bombarding radium with neutrons. **SYNTHESIS OF ELEMENTS** - **TRANSURANIC ELEMENTS** -- are elements artificially produced in nuclear reactors or accelerators. \- Are synthetic elements with atomic numbers higher than that of Uranium (Z = 92). \- In 1930 the heaviest element known was uranium, with an atomic number 92. \- Actinides: elements 93, Neptunium to 103, Lawrencium \- Transactinides: elements 104, rutherfordium to 118, ununoctium. HEAVY ELEMENTS. - Early in 1940, Edwin McMillan proved that an element having an atomic number 93 could be created. NEPTUNIUM - At the end of 1940, element-94 was synthesized by Seaborg, McMillan, Kennedy, and Wahl. PLUTONIUM. - **CYCLOTRON** - a device used to accelerate (speeds-up) particles to produce heavier nuclei upon hitting a target nuclei. **FORMATION OF ARTIFICIAL ELEMENTS SAMPLES:** **Curium (Z=96)** was formed by reacting Plutonium, Pu-239 with alpha particles 4He. It has a half-life of 162 days. **Mendelevium (z=101)** was formed by reacting Einsteinium, Es-253 with alpha particles. **LESSON 3: POLARITY OF MOLECULES** **Properties of Metals** 1. Good conductors of heat and electricity 2. Shiny. 3. Ductile 4. Malleable 5. Corrosion. **Properties of Non-Metals** 1\. Poor conductors of heat and electricity 2\. Not ductile or malleable 3\. Brittle and break easily 4\. Dull 5\. Many non-metals are gases. **Properties of Metalloids** 1. Have properties of both metals and non-metals 2. Solids that can be shiny or dull. 3. Conduct heat and electricity better than non- metals but not as well as metals. 4. They are ductile and malleable. **Valence Electron & Lewis Dot Symbol** **Valence electrons** are the "outermost electrons" of the atom involved in chemical bonding. **Octet Rule** states that atoms tend to form compounds in ways that give them eight valence electrons and thus the electron configuration of a noble gas. **Lewis Dot Symbols/Structures** are diagrams that represent the valence electrons of an atom. **POLARITY** - is the separation of an electric charge which leads a molecule to have a positive and negative end. The distribution of electrical charge over the atoms joined by the bond. - State or a condition of an atom or a molecule having positive and also negative charges, especially in case of magnetic or an electrical poles. - Can be determined by two factors: electronegativity difference and molecular geometry through the VSEPR (Valence Shell Electron Pair Repulsion) theory **POLARITY: ELECTRONEGATIVITY DIFFERENCE** - If the electronegativity difference (AEN) is less than or equal to 0.4, the bond is nonpolar covalent. - If the AEN is greater than 0.4 but less than 1.9, the bond is polar covalent. - If the AEN is greater than 1.9, then the bond is ionic. **POLARITY** **Ionic compounds** - are highly polar since ions are charged atoms. **Polar Covalent** -- electrons are shared unequally. The difference in electron density creates a dipole moment. **Nonpolar Covalent -** electrons are shared equally. Electrons are distributed equally, so there'll be no chance to have a partial positive and partial negative end. **POLARITY: MOLECULAR GEOMETRY** - For polyatomic molecules, the molecular geometry shapes determine the overall molecular polarity. - VSEPR is a model used to predict the geometry of molecules based on minimizing the electrostatic repulsion of a molecule's valence electrons around a central atom. - Each "group" of valence electrons (electron group) around a central atom must be located as far as possible from other groups in order to minimize repulsions. - Electron group pertains to a number of electrons that occupy a specific region around an atom; it may be lone pair, single bond, double bond, or triple bond. **LESSON 4:** **Matter** - is the particle that give its mass and volume. **Chemosynthesis** -- Is the process that creates new atomic nucleus from pre- existing nucleons, which is proton and neutrons. **Isotopes** - Are atoms of the same element that have the same atomic number(Z) but different mass number (A). **Isotopes notation -** One way to identify the different isotopes of an element. It has four parts: Symbol (X) mass number (A) Atomic number (Z) **AZE Notation** - is the standard isotope notation, where A is the mass number, Z the atomic number, and E the element's chemical symbol. **ISOTOPES AND MASS NUMBER OF ELEMENTS** Hydrogen has the simplest nucleus among all the elements. It has only 1 proton in its nucleus. Thus its atomic mass is just 1.008 atomic mass unit (amu) However, some hydrogen atoms have an additional neutron in their nuclei. **ATOMIC MASS AND ISOTOPIC ABUNDANCE** Isotopic abundance refers to the relative number of atoms of the different isotopes of one chemical element. It is usually expressed as a percentage of the total of all the long-lived isotopes of a given element, either in nature or in some reference state. Isotopic abundances are most often quoted as atom percentages. Example: Carbon has three fundamental isotopes: carbon-12, carbon-13 and carbon -14. "C-12 is the lightest, has 6 proton, electron and 6 neutrons per atom. (98.89%) "C-13 has a medium weight structure. Has 6 protons and electrons and 7 neutrons. (1.11%) "C-14 is the rarest and heaviest among the 3. Has, 6 protons, six electrons, and 8 neutrons. (\