Basic Chemistry Flashcards (Video Notes)

Key Terms and Core Concepts

  • Atom: the basic unit of an element that retains its chemical properties; composed of three main subatomic particles and a surrounding electron cloud.
    • Nucleus contains protons and neutrons.
    • Electrons form an electron cloud around the nucleus.
  • Proton: positively charged subatomic particle located in the nucleus; symbolically contributes to the atomic number Z.
  • Neutron: electrically neutral subatomic particle located in the nucleus; contributes to atomic mass.
  • Electron: negatively charged subatomic particle surrounding the nucleus; mass is negligible compared to protons and neutrons.
  • Charge: the net electric charge of an atom or ion. Neutral atoms have equal numbers of protons and electrons.
  • Atomic number (Z): number of protons in the nucleus; defines the identity of the element (e.g., H has Z = 1, C has Z = 6).
  • Mass number (A): total number of protons and neutrons in the nucleus; A = Z + N.
  • Isotope: atoms of the same element (same Z) with different numbers of neutrons (different A).
  • Mass: often discussed as atomic mass or molar mass; in isotopes, mass differs due to different neutron counts. Atomic mass unit (amu) is used for individual atoms; molar mass (g/mol) is used for quantities of material.
  • Ion: a charged particle formed when electrons are gained or lost.
    • Cation: positively charged (loss of electrons).
    • Anion: negatively charged (gain of electrons).
  • Neutral atom: same number of protons as electrons; overall charge is zero.
  • Electron configuration (not fully detailed here) describes how electrons populate shells/orbitals and helps explain reactivity and bonding.

Atomic Structure: Z, A, and Neutrons

  • Protons (Z) identify the element; neutrons (N) add to mass; electrons (E) balance charge in neutral atoms.
  • Key relationships:
    • N = A − Z
    • For a neutral atom: E = Z
    • For ions: E = Z − (charge of the ion)
    • Example: Na⁺ has Z = 11 and charge +1, so E = 11 − 1 = 10.
  • Isotopes vs. elements:
    • All isotopes of an element have the same Z but different A.
    • Examples of common isotopes (Z and A):
    • Aluminum-27: Z = 13, A = 27
    • Sodium-23: Z = 11, A = 23
    • Iodine-127: Z = 53, A = 127
    • Rubidium-85: Z = 37, A = 85
    • Copper-64: Z = 29, A = 64
    • Titanium-48: Z = 22, A = 48
    • Molybdenum-98: Z = 42, A = 98
    • Bismuth-209: Z = 83, A = 209
    • Tungsten-184: Z = 74, A = 184
  • Example calculations:
    • For Aluminum-27 (Al-27):
    • Z = 13, A = 27
    • N = A − Z = 27 − 13 = 14
    • E = Z for neutral atom = 13
    • Mass contribution of nucleus (approximate for a single atom) is ~A protons + neutrons in amu.
    • For Sodium-23 (Na-23):
    • Z = 11, A = 23
    • N = 23 − 11 = 12
    • E = 11 (neutral atom)
  • Quick rule of thumb: the mass number A is the integer count of nucleons (p+n) in the nucleus; the atomic mass on the periodic table is a weighted average of isotopic masses, not a single A.

Completing a Table of Nuclei (Example Fill-In)

  • Use a periodic table to obtain Z (Atomic Number) for each symbol; choose a representative isotope if A is given.
  • Example filled rows (illustrative and accurate):
    • Aluminum-27 (Al): Z = 13, A = 27, P = 13, N = 14, E = 13
    • Sodium-23 (Na): Z = 11, A = 23, P = 11, N = 12, E = 11
    • Iodine-127 (I): Z = 53, A = 127, P = 53, N = 74, E = 53
    • Rubidium-85 (Rb): Z = 37, A = 85, P = 37, N = 48, E = 37
    • Copper-64 (Cu): Z = 29, A = 64, P = 29, N = 35, E = 29
    • Titanium-48 (Ti): Z = 22, A = 48, P = 22, N = 26, E = 22
    • Molybdenum-98 (Mo): Z = 42, A = 98, P = 42, N = 56, E = 42
    • Bismuth-209 (Bi): Z = 83, A = 209, P = 83, N = 126, E = 83
    • Hydrogen-1 (H): Z = 1, A = 1, P = 1, N = 0, E = 1
    • Tungsten-184 (W): Z = 74, A = 184, P = 74, N = 110, E = 74
  • Note: Some rows in the original transcript were garbled; use standard, well-known isotopes when practicing calculations.

Ionic and Covalent Nomenclature: Names and Formulas

Ionic Compounds: Name and write formulas

  • Naming rule: name of the cation (usually a metal or NH₄⁺) followed by the name of the anion.
  • For monoatomic cations from main-group elements, no Roman numeral is needed unless the metal can form ions with more than one common charge. Then use Roman numerals.
  • Common examples (with formulas):
    • Sodium chloride → NaCl
    • Chlorine gas (element) → Cl₂ (not an ionic compound but a diatomic element)
    • Calcium bromide → CaBr₂
    • Iron(III) oxide (rust) → Fe₂O₃
    • Potassium nitrate → KNO₃
    • Copper(II) sulfate → CuSO₄
  • Notes on mis-typed items in the transcript: “calcien” → calcium; “bramite” → bromide; “Iron vide” → iron oxide; “Copper Caltate” → copper carbonate or copper(II) salt depending on context. The standard ionic formulas shown above are the correct forms from common naming conventions.

Molecular Compounds: Names and Formulas

  • Molecular compounds are named using prefixes to indicate the number of each type of atom in the molecule (except often for the first element when it is 1).
  • Examples (with formulas):
    • Carbon dioxide → CO₂
    • Dinitrogen tetroxide → N₂O₄
    • Diphosphorus pentoxide → P₂O₅
    • Sulfur trioxide → SO₃
    • Nitric oxide → NO
  • Note: These are covalent compounds, and the prefixes (mono-, di-, tri-, etc.) are used to convey the number of each type of atom.

Basic Chemistry Math: Core Formulas and Practice

  • Molar mass (molar mass of an element):
    • M_i = atomic mass of element i (in g/mol) (approximate integer mass numbers for isotopes are a teaching simplification; the real molar mass is a weighted average)
  • Formula mass for compounds:
    • Molar mass of a compound = sum over elements of (number of atoms of element i) × (molar mass of element i)
  • Moles to grams conversion:
    • n(moles) = mass(g) / M(self-consistent with Fórmula above)
  • Grams from moles:
    • mass(g) = n(moles) × M
  • Isotopic mass vs. molar mass: isotopic masses are close to whole-number A values, while molar mass on the periodic table is the weighted average of all isotopes in a natural sample.
  • Percent composition by mass:
    • mass percent of element i in a compound = (ni × Mi) / M_total × 100%
  • Quick example for a diatomic molecule (O₂, M = 32.00 g/mol):
    • If you have 2.0 g of O₂, moles = 2.0 / 32.00 ≈ 0.0625 mol

Periodic Table: Memorization and Use

  • Element symbols and names (select examples from the transcript):
    • Pt → Platinum
    • Hf → Hafnium
    • Pu → Plutonium
    • Sb → Antimony
    • He → Helium
    • K → Potassium
    • H → Hydrogen
    • Ra → Radium
    • I → Iodine
    • Rn → Radon
    • Ba → Barium
    • Ir → Iridium
    • Fe → Iron
    • Sc → Scandium
    • Se → Selenium
    • Kr → Krypton
    • La → Lanthanum
    • Si → Silicon
    • Pb → Lead
    • Ag → Silver
    • Cd → Cadmium
    • Ca → Calcium
    • Li → Lithium
    • Mg → Magnesium
    • Mn → Manganese
    • Hg → Mercury
    • Mo → Molybdenum
    • Ne → Neon
    • Ni → Nickel
    • N → Nitrogen
    • O → Oxygen
    • Ga → Gallium
    • Au → Gold
    • Pd → Palladium
    • P → Phosphorus
    • Sn → Tin
    • Xe → Xenon
    • Zn → Zinc
  • Ions: common polyatomic and simple ions (names and formulas)
    • Ammonium:
    • NH₄⁺
    • Acetate:
    • CH₃COO⁻ (or C₂H₃O₂⁻)
    • Carbonate:
    • CO₃²⁻
    • Cyanide:
    • CN⁻
    • Dichromate:
    • Cr₂O₇²⁻
    • Chromate:
    • CrO₄²⁻
    • Hydroxide:
    • OH⁻
    • Peroxide:
    • O₂²⁻
    • Hydrogen carbonate (bicarbonate):
    • HCO₃⁻
    • Nitrate:
    • NO₃⁻
    • Nitrite:
    • NO₂⁻
    • Sulfate:
    • SO₄²⁻
    • Sulfite:
    • SO₃²⁻
    • Phosphate:
    • PO₄³⁻
    • Phosphite:
    • PO₃³⁻
    • Chlorate:
    • ClO₃⁻
    • Chlorite:
    • ClO₂⁻
    • Chloride:
    • Cl⁻
    • Hypochlorite:
    • ClO⁻
    • Perchlorate:
    • ClO₄⁻
    • Permanganate:
    • MnO₄⁻
  • Mercury(I) ion: Hg₂²⁺ (diatomic mercury ion in some contexts)

Practice: How to Fill the Particle Table (Step-by-Step)

  • Given a symbol, to fill Protons (P), Neutrons (N), and Electrons (E) for a specific isotope:
    1) Identify Z from the periodic table (P = Z).
    2) If the isotope is specified as A (mass number), compute N = A − Z.
    3) If the atom is neutral, E = Z. If it has a charge, E = Z − (charge).
  • Example table entries (illustrative and accurate):
    • Symbol: Al, A = 27
    • Z = 13, A = 27, P = 13, N = 27 − 13 = 14, E = 13 (neutral)
    • Symbol: Na, A = 23
    • Z = 11, A = 23, P = 11, N = 12, E = 11 (neutral)
    • Symbol: I, A = 127
    • Z = 53, A = 127, P = 53, N = 74, E = 53 (neutral)
    • Symbol: Rb, A = 85
    • Z = 37, A = 85, P = 37, N = 48, E = 37 (neutral)
    • Symbol: Cu, A = 64
    • Z = 29, A = 64, P = 29, N = 35, E = 29 (neutral)
    • Symbol: Ti, A = 48
    • Z = 22, A = 48, P = 22, N = 26, E = 22 (neutral)
    • Symbol: Mo, A = 98
    • Z = 42, A = 98, P = 42, N = 56, E = 42 (neutral)
    • Symbol: Bi, A = 209
    • Z = 83, A = 209, P = 83, N = 126, E = 83 (neutral)
    • Symbol: H, A = 1
    • Z = 1, A = 1, P = 1, N = 0, E = 1 (neutral)
    • Symbol: W, A = 184
    • Z = 74, A = 184, P = 74, N = 110, E = 74 (neutral)
  • Note: If you see a charge in the problem (e.g., Na⁺ or Cl⁻), adjust E accordingly using E = Z − charge.

Real-World Relevance and Ethical/Practical Notes

  • Isotopes have medical and industrial applications (e.g., radioisotopes in imaging and therapy) and are also used in dating techniques and environmental tracing.
  • Understanding ionic vs. covalent bonding informs material design, pharmaceuticals, and environmental chemistry (pollutants, fertilizers, electrolytes).
  • Accurate nomenclature and formula writing are foundational for communicating chemical information in labs, industries, and academia.

Quick Reference Formulas (LaTeX)

  • Neutron count: N = A - Z
  • Electron count for neutral atom: E = Z
  • Electron count for ion: E = Z - ext{(charge)} where charge is positive for cations and negative for anions.
  • Molar mass of a compound: M{ ext{compound}} = extstyleigg( ext{sum over elements } i ig(ni imes M_iig)igg)
  • Moles from mass: n = rac{m}{M}
  • Mass from moles: m = n imes M
  • Percent composition by mass: $$ ext{wt}\%i = rac{ni Mi}{M{ ext{compound}}} imes 100\