CHM 104 Module 2 - Vocabulary Flashcards

Subatomic Particles

  • Proton: +1 charge; location: nucleus
  • Neutron: 0 charge; location: nucleus
  • Electron: -1 charge; location: electron cloud (outside nucleus)

Atomic Number, Mass, and Isotopes

  • Atomic number (Z) = number of protons in the atom
  • Mass number (A) = total number of protons and neutrons
  • Isotopes: atoms with same Z but different N (different A)
  • Isotones: atoms with same number of neutrons (N) but different Z
  • Isobars: atoms with same mass number (A) but different Z and N

Modern Atomic Theory (essential takeaway)

  • Atoms of different elements combine in whole-number ratios to form compounds.
  • Atoms of the same element are not necessarily identical in all isotopes; isotopes exist due to different neutron numbers.

Atomic Mass and Isotopes

  • The atomic mass of an element is a weighted average of the masses of its isotopes:
    A{ ext{avg}} = \sumi fi Ai
    where $fi$ is the fractional abundance and $Ai$ is the mass number of isotope $i$.
  • Example: Uranium with ~98% U-238 and ~2% U-235
    A_{ ext{avg}} = 0.98\times 238 + 0.02\times 235 = 237.94 \text{ amu}

Nuclear Symbol Notation

  • Nuclear symbols use format: ^{A}_{Z}\mathrm{X} where $A$ is mass number, $Z$ is atomic number, and X is the element symbol.
  • Examples:
    • Strontium-88: ^{88}_{38}\mathrm{Sr}
    • Bromine-82: ^{82}_{35}\mathrm{Br}
    • Boron-10: ^{10}_{5}\mathrm{B}
    • Neon-20: ^{20}_{10}\mathrm{Ne}

Short Answer Practice: Particle Knowledge

  • List each subatomic particle, its charge, and location:
    • Proton: charge $+1$, location in the nucleus
    • Neutron: charge $0$, location in the nucleus
    • Electron: charge $-1$, location in the electron cloud

Counting Protons, Neutrons, and Electrons

  • For a neutral atom, #protons = #electrons; neutrons = $A - Z$ where $A$ is mass number and $Z$ is atomic number.
  • Examples from the practice:
    • Sr-88: Z = 38 → protons = 38; neutrons = $88 - 38 = 50$; electrons = 38
    • Br-82: Z = 35 → protons = 35; neutrons = $82 - 35 = 47$; electrons = 35
    • B-10: Z = 5 → protons = 5; neutrons = $10 - 5 = 5$; electrons = 5
    • Ne-20: Z = 10 → protons = 10; neutrons = $20 - 10 = 10$; electrons = 10

Element Classification (Metals, Nonmetals, Metalloids)

  • Sodium: metal
  • Chlorine: nonmetal
  • Oxygen: nonmetal
  • Copper: metal
  • Silicon: metalloid
  • Potassium: metal
  • Selenium: nonmetal

Element Identification by Period/Group (as per practice)

  • a) In period 5 and a transition metal with 2 valence electrons → strontium (note: strontium is in period 5, group 2; described as a metal in the practice key)
  • b) A metalloid in period 3 → silicon
  • c) A noble gas in period 6 → radon
  • d) A nonmetal with 5 valence electrons in period 2 → nitrogen
  • e) An element in period 4 and group 17 → bromine
  • f) An element in group 15 and period 4 → arsenic

Family Names (Periodic Table Groups)

  • a. Helium → Noble gas
  • b. Sulfur → Chalcogen
  • c. Sodium → Alkali metal
  • d. Magnesium → Alkaline earth metal
  • e. Iron → Transition metal
  • f. Bromine → Halogen
  • g. Phosphorus → Pnictogen