We can draw an analogy between the attraction of an electron to a nucleus and seeing a lightbulb-in essence, the more nuclear charge the electron "sees," the greater the attraction.
1. Within this analogy, discuss how the shielding by core electrons is analogous to putting a frosted-glass lampshade between the lightbulb and your eyes, as shown in the illustration. (See figure attached)
2. Explain how we could mimic moving to the right in a row of the periodic table by changing the wattage of the lightbulb.
3. How would you change the wattage of the bulb and/or the frosted glass to mimic the effect of moving down a column of the periodic table?
4. What is meant by the term effective nuclear charge?
5. Explain the following variations in atomic or ionic radii.
a. I- >I>I+
b. Ca2+ >Mg2+>Be2+
c. Fe >Fe2+>Be3+
6. For each of the following pairs, indicate which element has the larger first ionization energy.
a. Ti, Ba (Use electron configuration and effective nuclear charge to explain your answer)
b. Ag, Cu (Use electron configuration and effective nuclear charge to explain your answer)
c. Ge, Cl (Use electron configuration and effective nuclear charge to explain your answer)
d. Pb, Sb (Use electron configuration and effective nuclear charge to explain your answer)
7. Explain how the 4s electron in an As atom has a lower energy that 4p electron in an As atom? Also, how can we use the concept of effective nuclear charge to explain this?
8. How do we determine the factors of the order of increasing melting point?
9. For each of these Lewis symbols, (Figure attached) indicate the group in the periodic table in which the element X belongs.
Enter your answers in order given in the figure below. For example, Chlorine is in group 7A.
1. If the frosted glass was absent, the eyes would feel the full effect of the light bulb. The frosted glass shields the eye from the full effect of the light. Similarly, the core electrons (frosted glass) shield the outermost electrons (eyes) from the full effect of the nucleus (light bulb). In essence, the core electrons make it seem like the nucleus has less charge than it actually has.
2. Moving to the right of the table does increase the number of protons as well as electrons. But the electrons are not added to new shells. This is like increasing the wattage of the light bulb but not increasing the distance between the bulb and the eyes. Hence the eyes feel a greater effect of the light bulb. Similarly, electrons feel the effect of the nucleus more as you go from left to right in the periodic table. The greater the effect, the more attracted the electrons are to the nucleus and hence it would be more difficult to remove these electrons resulting in higher ionization energies.
3. Moving down a column, you increase protons as well as electrons. But here, the electrons are added to shells further and further away from the nucleus. This is like increasing the wattage but also increasing the distance between the bulb and the eyes. Hence the eyes don't feel the full effect of the bulb as they are further away ...
The expert draws an analogy between the attraction of an electron to a nucleus and seeing a lightbulb-in essence.