Chemistry Quiz: Isotopes & Periodic Table

Verifying Food Quality: Carbon Isotopes of Honey

• Honey is a valuable product, but some manufacturers dilute it with cheaper sugars to increase profits.
• The ratio of carbon-13 to carbon-12 isotopes in honey is different from other sugars.
• By measuring this ratio, we can determine if a honey sample is pure.

Navigating the Periodic Table – Regions

• The periodic table is organized by atomic number.
• Elements are frequently grouped into four regions: main group metals, transition metals, metalloids, and nonmetals.
• These categories are defined by similar chemical properties.

Navigating the Periodic Table – Groups

• Elements within a group share similar chemical and physical properties, including: electron configuration, electronegativity, ionization energy, ionic charge, and electical conductivity.

Navigating the Periodic Table – Periods

• The period number corresponds to the principle quantum number of the electronic orbitals of its atoms.
• Elements in each successive period tend to exhibit more metallic character, this is especially important for groups 13 through 16.

Elemental Symbols

• Elemental symbols can include additional information, indicated by numbers in specific locations.
• Upper left: mass number (mi), total number of protons and neutrons in an atom.
• Upper right: Ionic charge (q), net electric charge on an atom.
• Lower left: Atomic number (Z), equal to the number of protons in an atom.
• Lower right: Number of atoms (N), number of atoms in a molecule or formula.

Identifying Isotopes

• The atomic number identifies an element and therefore the number of protons.
• The mass number is equal to the sum of protons and neutrons.
• Number of neutrons in an atom can be determined by subtracting the atomic number (protons) from the mass number.

Isotopic Abundance and Average Atomic Mass

• The atomic mass found on the periodic table is the weighted average of the masses for each stable isotope.
• The atomic mass (amu) is equivalent to the number of grams in a single mole of that element (1 amu = 1 g/mol).
• This average weight is calculated by taking the average of each isotope's mass, multiplied by their relative abundance.
• Average atomic mass = ∑ (mass of isotope * relative abundance of isotope) for all isotopes.

Quantifying Matter – The Mole

• The amount of a substance (n) is quantified in moles (mol), where 1 mole = 6.022 x 10^23 somethings.
• These "somethings" can be atoms, molecules, or other particles.
• Avogadro's number (NA) is 6.022 x 10^23 mol−1.
• The amount of substance (in moles) is equal to its mass (m) divided by its molecular mass (M): n (mol) = m (g)/M (g/mol)

Molar Mass

• The molecular mass (M) is the sum of the atomic masses of all the atoms in a molecule.
• To calculate the mass of a substance given the number of moles, multiply the number of moles by the molecular mass.
• To calculate the number of moles of a substance given the mass, divide the mass by the molecular mass.

Knowledge Development Questions

• The ratio of carbon-13 to carbon-12 isotopes is used to determine the purity of honey.
• The carbon-13 to carbon-12 isotope ratio in doped honey is larger than the ratio in pure honey.
• To determine the number of electrons in an anion, add the number of protons for the element to the negative charge.
• To find the average atomic mass of an element, take the weighted average of all isotopes, accounting for their relative abundance.
• The average atomic mass of a cation is equal to the average atomic mass of the element.
• To determine the number of electrons in a cation, subtract the positive charge from the number of protons for the neutral element.

This quiz covers two main topics in chemistry: verifying food quality using carbon isotopes in honey, and understanding the organization of the periodic table. You will learn how isotope ratios can indicate honey purity and explore the characteristics of various element regions, groups, and periods. Test your knowledge on these essential concepts in chemistry!