Chemistry Exam: Pure Substances & Atomic Structure

Exam Instructions

• The exam contains 6 pages with 14 questions.
• The Periodic Table of the Elements can be detached.
• Use blank pages as scratch paper.
• Put answers only in the space provided.
• No unauthorized assistance is permitted.

Question 1: Classifying Pure Substances

• Classify each of the following substances as a compound, covalent substance, metal, or non-metal: BeF2, Bi, SiO2, O3, He, graphene.

Question 2: Atomic Particles

• a) Determine the number of protons, electrons, and neutrons in one atom of fluorine-18.
• b) Given the number of protons, electrons, and neutrons, determine the formula of the monoatomic species.

Question 3: Moles and Avogadro's Number

• Calculate the number of moles of hydrogen atoms in 1.00 g of NH3BH3 (molecular mass 30.87 amu).

Question 4: Mass of Atomic Mass Unit

• Calculate the mass in grams of 1 atomic mass unit (amu) using the definition of the mole, the atomic mass unit, and physical constants provided on page 5.

Question 5: Identifying an Element from Atom Count

• Identify the element in a 10.0 g sample containing 4.39 × 10^22 atoms.

Question 6: Ions in Substances

• a) List the formulas of ions present in Na2HPO4(s).
• b) List the major monoatomic cations derived from lead.
• c) List the ions present in PI3(s).
• d) List the ions present in Ti2O3(s).
• e) List the major monoatomic anions derived from sulfur.

Question 7: Naming and Formula Writing

• Provide the systematic name or chemical formula for each of the following substances:
  • a) barium peroxide
  • b) NaClO
  • c) CuF2
  • d) GeCl4
  • e) aluminum hydrogen sulfate

Question 8: Ionization Energy and Wavelength

• Calculate the maximum wavelength in nm of the electromagnetic wave that can ionize an atom with a first ionization energy of 1402 kJ/mol.

Question 9: Atomic Orbital Designations

• Provide a designation (e.g., 4dxy) for the atomic orbitals with the given set of quantum numbers:
  • a) n = 3, l = 0, with no nodal planes
  • b) n = 2, l = 1, with a nodal plane x = 0
  • c) n = 2, l = 2, with two nodal planes, x = 0 and y = 0

Question 10: Atomic Orbital Drawings

• Provide a designation (e.g., 5p) for each of the atomic orbital drawings:
  • a) Cross-section drawing of an atomic orbital
  • b) Cross-section drawing of an atomic orbital

Question 11: Orbital Diagram of Ge2+

• Provide the full orbital diagram for the Ge2+ ion in its ground state.

Question 12: Unpaired Electrons and Valence Electrons

• a) Indicate the number of unpaired electrons in the following species in their ground state configuration:
  • i) Ca, [Ar]4s2
  • ii) Cr2+, [Ar]3d4
  • iii) S, [Ne]3s23p4
• b) Indicate the number of valence electrons in the following species: -i) Al -ii) Pd -iii) Xe

Question 13: Periodic Trends

• Arrange the following species in order of increasing:
  • a) Atomic radius: Al, Ne, Ca
  • b) Ionic radius: I-, Br-, Rb+
  • c) Electron affinity: Ne, H, F
  • d) Ionization energy: Li, N, Si

Question 14: Empirical Formula of Alizarin

• Determine the empirical formula of alizarin, a natural pigment containing 70.00% C, 3.36% H, and 26.64% O by mass.