Phy Sci (Chemistry) 2nd Semester Midterms

• Dalton's spherical model of the atom


  Atoms are like very small, indivisible and indestructible spheres with mass
• Planetary Model of the Atom

  The nucleus is at the center of the atom surrounded by electrons that follow certain imaginary circular orbits
• Quantum Mechanical Model


  The model of the atom proposed by Erwin Schrodinger and Werner Heisenberg, the nucleus is surrounded by electron clouds
• Quantum Model of the Atom

  The nucleus is surrounded by electron clouds
• Important Features of the Quantum Model

  • Main energy levels (describe the total energy of the electrons)
  • Energy sublevels (describe the shapes of space where the electrons are moving)
  • Orbitals (the region of space occupied by the electrons)
• Types of Energy Sublevel


  • s (spherical) - has only 1 orbital, 2 electrons
  • p (principal) - has 3 orbitals, 6 electrons
  • d (diffused) - has 5 orbitals, 10 electrons
  • f (fundamental) - has 7 orbitals, 14 electrons
• Electron Configuration


  Describes the arrangement or distribution of electrons in an atom
• Rules to be followed for Electron Configuration

  • Aufbau Principle (electrons occupy the available orbitals in order of increasing energy)
  • Hund's Rule of Multiplicity (when electrons enter a sublevel with more than one orbitals, they will occupy first all the available orbitals with their spins in the same direction before they pair up with another electron of opposite spin)
  • Pauli's Exclusion Principle (two electrons occupying the same orbital must have opposite spins, no two electrons in an atom can have the same set of quantum numbers)
• Writing of Electron Configuration


  • 9F - 1s2 2s2 2p5
  • 15P - 1s2 2s2 2p6 3s2 3p3
  • 20Ca - 1s2 2s2 2p6 3s2 3p6 4s2
  • 30Zn - 1s2 2s2 2p6 3s2 3p6 4s2 3d10
  • 40Zr - 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d2
  • 50Sn - 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p2
  • 60Nd - 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f4
• In 1800-1849, 24 new elements were discovered
• Law of Triads


  The middle element in the triad had atomic weight that was the average of the other two members
• In 1850-1899, 26 new elements were added
• Telluric Helix


  Elements are arranged in spiral form by order of increasing atomic weights, those with similar properties lined up vertically
• Law of Octaves


  Arranged the 62 known elements in order of increasing atomic weights, noted that after interval of eight elements, similar physical and chemical properties reappeared
• Dmitri Ivanovich Mendeleev


  Arranged the elements in order of increasing atomic weights and found apparent periodicity of properties, left vacant spaces for new elements to be discovered
• In 1900-1949, 13 new elements were discovered
• Henry Moseley


  Arranged the elements in increasing atomic numbers and found a relationship between the elements' x-ray frequencies and their atomic numbers, summarized this by stating the modern periodic law
• Glenn Seaborg


  Discovered transuranium elements 94 to 102 and reconfigured the periodic table by placing the lanthanide and actinide series at the bottom of the table
• Important Features of the Periodic Table

  • Horizontal Rows (7 Periods)
  • Vertical Columns (18 Groups)
  • Blocks (s, p, d, f)
• Periodic Table Groups


  • Representative Elements (A Group) - s and p blocks elements
  • Transition Elements (B Group) - d block elements
  • Inner Transition Elements - f block elements
• Determining the Period, Group, and Valence Electrons

  Period - number of main energy levels

  Group - number of valence electrons

  Valence electrons - number of electrons in the outermost shell
• Characteristics of Metals and Nonmetals

  • Metals - with 3 or lesser valence electrons, good conductors of heat and electricity, high melting points, malleable, ductile

  Nonmetals - with 4 or more valence electrons, good insulators, low melting points, brittle
• Representative Elements Groups


  • 1A - Alkali metals

  2A - Alkaline-earth metals

  3A - Boron group

  4A - Carbon group

  5A - Nitrogen group

  6A - Oxygen group

  7A - Halogen group

  8A - Noble gases
• Electron Configuration for Groups

  • 1A - s1

  1B - s1 d10

  2A - s2

  2B - s2 d10

  3A - s2 p1

  3B - s2 d1

  4A - s2 p2

  4B - s2 d2

  5A - s2 p3

  5B - s2 d3

  6A - s2 p4

  6B - s2 d4

  7A - s2 p5

  7B - s2 d5

  8A - s2 p6

  8B - s2 d6

  8B - s2 d7

  8B - s2 d8
• Physical Science


  Branch of natural science concerned with the study of non-living natural objects (composition, physical and chemical properties)
• Chemistry


  A physical science that deals with the study of matter
• Astronomy


  A natural science that studies celestial objects and phenomena; the study of everything in the universe beyond Earth's atmosphere. Objects of interest include planets, moons, stars, nebulae, galaxies, and comets.
• Cosmology


  A branch of astronomy that studies the origin of the universe and how it has evolved.
• Topics


  • The Big Bang Theory
  • Atomic Structure
  • The Modern Periodic Table
  • Chemical Bonding
  • Naming of Inorganic Compounds
  • The Mole Concept
  • Chemical Reactions
  • Household and Personal Care Products
• Element


  The simplest form of matter; a chemical substance that cannot be broken down into other substances.
• Classification of elements


  • Solid
  • Liquid
  • Gas
  • Metal
  • Nonmetal
  • Metalloid
• Matter


  Anything that occupies space and has mass.
• Big Bang Theory


  The theory that states that about 13.8 billion years ago, the universe expanded from an extremely small, hot, and dense point called a singularity.
• Singularity


  A region of space where the density of matter, or the curvature of spacetime, becomes infinite. Here, the standard concepts of space and time cease to have any meaning. Singularities are predicted to occur in all black holes and also in certain models of the Universe.
• Timeline of the Big Bang Theory

  1. Singularity (concepts of time, space, matter and energy do not exist)

  2. Happening of the Big Bang (concepts of time, space, matter and energy started, aside from gravity other natural forces existed, present was only plasma made of very small fast-moving charged particles)

  3. After 300,000 years (electrons, protons and neutrons combined forming the first light elements)

  4. After one billion years (H and He atoms began to form giant clouds that became the galaxies and stars)

  5. After several billion years (universe continued to expand and cool, first stars died and emitted energy causing the formation of other elements)
• The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.
• Galaxy


  A huge collection of gas, dust, and billions of stars and their solar systems, all held together by gravity.
• Evidences for the Big Bang Theory

  • Most of the galaxies appear red shifted, an indication that they are moving away from us and that the universe is expanding
  • The remnant radiation from the Big Bang is observed today as the cosmic microwave background radiation (CMB), a low-level radiation with a temperature of 2.725 K
  • The percentage of light elements such as hydrogen and helium agree with the idea that the universe started in a hot and dense phase
• Steady-state theory


  A view that the universe is always expanding but maintaining a constant average density, with matter being continuously created to form new stars and galaxies at the same rate that old ones become unobservable as a consequence of their increasing distance and velocity of recession.
• Our galaxy is called the Milky Way because it appears as a milky band of light in the sky when you see it in a really dark area. It is very difficult to count the number of stars in the Milky Way from our position inside the galaxy.