Study Guide – Atoms Test

  • Describe the development of the model of atomic structure (include Dalton, Thompson, Rutherford, Bohr models)
  • State the relative charges and approximate relative masses of protons, neutrons and electrons
  • Describe the composition of an atom including the forces acting with the atom (nuclear, electrostatic)
  • Define the terms; atomic number, mass number, valence electrons, isotopes, relative atomic mass (Ar), relative molecular mass (Mr), mole, Avogadro’s constant
  • Draw Bohr models of atoms, isotopes and ions up to atomic number 20
  • Draw Lewis structures of atoms and ions up to atomic number 20
  • Distinguish the number of protons, neutrons, and electrons in atoms, ions, and isotopes.
  • Describe the build-up of electrons in ‘shells’ and understand the significance of the noble gas electronic structures and of valence electrons (the ideas of the distribution of electrons in s and p orbitals and in d block elements are not required.)
  • Interpret chemical formulas
  • Calculate the molar mass given any compound
  • Use molar mass to convert between mass in grams and amount in moles of a chemical compound.
  • Solve problems involving mass in grams, amount in moles, and number of atoms in an element.
  • Use dimensional analysis to perform calculations.
  • Perform mathematical calculations involving significant figures.

Practice Problems:

  1. Make a table showing the development of the structure of an atom. In the table include the name of the scientist responsible for each model, the name of the model, the basic experiment that led to a new discovery in the model, a picture of the model, and a description of the atomic model.
  2. Explain the basic structure of an atom. Include the subatomic particles, where they are located, and what their charges and masses are.
  3. Define atomic number and mass number. Explain what these two numbers tell us about an atom.
  4. Draw the Bohrmodel for two different isotopes of calcium; Ca-42 and Ca-44
  5. Draw the Lewis structures for the atoms and the ions of; aluminum and sulfur
  6. Define the following terms: valence electrons, isotopes
  7. Why are elements in the last column of the periodic table the most stable (non-reactive) elements?
  8. What is a mole?
  9. What is Avogadro’s number?
  10. Determine the atomic mass for the following elements:

  1. Ca
  2. Xe
  3. K

  1. The element Rhenium (Re) has two naturally occurring isotopes 185Re and 187Re. 185Re has a mass of 184.953 amu and an abundance of 37.40%. 187Re has a mass of 186.956 amu and an abundance of 62.60%. Calculate the relative atomic mass of Re. What can you tell about the accuracy of your experimental data? Explain.
  2. Determine the molar mass for the following molecules/compounds

  1. NaCl
  2. H2O
  3. O2
  4. Fe2O3
  5. Na2O
  6. Cl2

  1. Determine the mass of the following samples

  1. 2 moles Co
  2. 5 moles H2
  3. 2.1 moles H2O

  1. Determine the number of moles in the following samples

  1. 54.2 g N2
  2. 202.2 g MgO
  3. 519.3 g FeCl3

  1. Determine how many atoms/molecules in the following samples

  1. 1.32 moles Si
  2. 7.29 mol CO2
  3. 712.4 g AuCl

  1. How many atoms of sodium are present in 5.50 grams of Na2HPO4? (careful, pay attention to compounds vs atoms)