Chemistry 102 – Chapter 2 Summary and Review Answers 1. What is the difference between naming an ionic compound and a binary molecular compound? Answer: Simple ionic compounds are named by: First word: name of the cation or metal; if this metal can have more than one ionic charge (most often transition metals), then this name is followed by the charge of the cation in Roman numerals. Second word: stem of the monoatomic ion with the suffix –ide; name of the anion without any alteration. Binary molecular compounds are named by: First word: name of the element of the first element given in the formula; if molecule contains more than one atom of the element, then the name is given the prefix corresponding to the number of atoms. Second word: name of the element of the second element given in the formula with the prefix corresponding to the number of atoms (including one) and the suffix –ide. 2. How does one generate or interpret a nuclear (or atomic) symbol? How is this translated into the name, for example, uranium‐238? Answer: To generate a nuclear symbol, A = number of neutrons + Z; the symbol is then AX (and also can include the atomic number). Similarly, the nuclear symbol can be interpreted to give the number of neutrons. A name is generated by using the name of the element‐mass number. 3. What is the difference between naming a binary acid and an oxoacid? Answer: A binary acid is named by: First word: hydro + stem of the anion + ide Second word: acid An oxoacid is named by: First word: stem of ion, remove the suffix if the suffix is: – ate add –ic –ite add –ous (Keep any prefix on the ion) Second word: acid 4. How does changing the number of electrons affect an atom? How do we represent this ion? What are the periodic trends for the formation of these ions? Answer: Changing the number of electrons affects the charge of the resulting species. This is represented by the number of electrons add or lost and the resulting charge as Xcharge. Group 1A forms ions with 1+, group 2A with 2+, group 3A with 3+, group 5A with 3–, group 6A with 2– and group 7A with 1–. What are the names of groups 1A, 2A, 7A, and 8A? 5. What are the definitions and the differences between atom, element, compound and molecule? Answer: These are in your textbook, both in the glossary and within the chapter. The definitions will not be given here as these are very important terms for you to understand. Find the definitions, read them, copy them down, and rephrase them in your own words (think about what these mean). 6. Show a particle representation of the two isotopes, boron‐10 and boron‐11. Knowing that the radius of an atomic nucleus is on the order of 10–3 pm while the radius of an atom is on the order of 102 pm, what is the correct scale representation of an atom to its nucleus (if the scale was 2 cm = 0.1 nm)? In other words, is your drawing of the nucleus or the nuclei in figures 2.8 or on page 36 of your textbook to the correct scale relative to the atom? Answer: Boron‐10 Boron‐11 where dark balls = neutrons and light balls = protons The drawing to the right would represent an atom (where the atom has been magnified to 4 cm – the diameter of the circle is 4 cm). Using the same magnification, the diameter of the nucleus is 0.4 μm. Knowing that the threshold of unaided human sight is 0.1 mm, would this be visible on the atom shown to the right? (no) Therefore, the drawings in the book take liberties by showing the nucleus (but it is necessary to show something even if it not to relative scale). What is the magnification?