Question

1. explore: examine other groups and periods in the periodic table to see if the same trends exist. what trends do you see in ionization energy down a group and across a period? 7. think and discuss: as you move down a group, you will recall that the radius increases. why do you think an increase in atomic radius would result in a lower ionization energy? 8. think and discuss: as you move across a period, you will recall that the radius decreases. why do you think a decrease in atomic radius would result in a greater ionization energy? 9. predict: electron affinity (ea) refers to the energy released when an electron is added to an atom. this release of energy is always expressed as a negative value. the greater the magnitude of the negative value, the greater the attraction for electrons. (an ea of -100 kj/mol would indicate a stronger attraction for electrons than an ea of -50 kj/mol.) how do you think the size of an atom will affect its ability to attract additional electrons?

Explanation:

1. Down a group, ionization energy decreases as the out - er electrons are farther from the nucleus and less tightly held. Across a period, ionization energy increases as the effective nuclear charge increases and the atomic radius decreases, making it harder to remove an electron.
2. As atomic radius increases down a group, the outermost electrons are farther from the nucleus. The attraction between the nucleus and the outermost electron is weaker, so less energy is required to remove the electron, resulting in lower ionization energy.
3. As atomic radius decreases across a period, the outermost electrons are closer to the nucleus and more strongly attracted to it. More energy is needed to remove an electron, leading to greater ionization energy.
4. Smaller atoms have a greater ability to attract additional electrons. The outermost electrons in a smaller atom are closer to the nucleus, so there is a stronger attraction for an added electron, resulting in a more negative electron - affinity value.

Answer:

1. Down - group: Decrease; Across - period: Increase
2. Weaker nuclear - electron attraction due to larger radius.
3. Stronger nuclear - electron attraction due to smaller radius.
4. Smaller atoms attract electrons more strongly.