Question

pd: ______ chemistry u3l14_q2 ct module day 3 hw
** 18.

element	n	p	as	sb	bi

the atomic radii of the elements in the nitrogen group in the periodic table are given in the table above. which of the following best helps explain the trend of increasing atomic radius from n to bi?
(a) the number of particles in the nucleus of the atom increases.
(b) the number of electrons in the outermost shell of the atom increases.
(c) the attractive force between the valence electrons and the nuclei of the atoms decreases.
(d) the repulsive force between the valence electrons and the electrons in the inner shells decreases.
** 19. which of the following best helps explain why the first ionization energy of k is less than that of ca?
(a) the electronegativity of k is greater than that of ca.
(b) the atomic radius of the k atom is less than that of the ca atom.
(c) the valence electrons of k experiences a lower effective nuclear charge than the valence electrons of ca.
(d) the nucleus of the k atom has fewer neutrons, on average, than the nucleus of the ca atom has.

1. which of the following best accounts for the decrease in the first - ionization energy of the alkaline earth metals going down the group?

(a) the number of protons in the nucleus increases, resulting in increased attraction between the nucleus and the electron being removed.
(b) the number of protons in the nucleus increases, resulting in a greater effective nuclear charge attracting the electron being removed.
(c) the number of electron shells increases, resulting in a greater average distance between the nucleus and the electron being removed.
(d) the number of electron shells increases, resulting in less shielding between the nucleus and the electron being removed.

• 21. which of the following elements has the largest first ionization energy?

(a) be
(b) li
(c) na
(d) mg

1. which of the following best helps to explain why the atomic radius of k is greater than that of br?

(a) the first ionization energy of k is higher than that of br.
(b) the valence electrons in k are in a higher principal energy level than those of br.
(c) in the ground state, an atom of k has fewer unpaired electrons than an atom of br has.
(d) the effective nuclear charge experienced by valence electrons is smaller for k than for br.

1. for parts of the free - response question that require calculations, clearly show the method used and the steps involved in arriving at your answers. you must show your work to receive credit for your answer. examples and equations may be included in your answers where appropriate.

Explanation:

1. For nitrogen group elements (N to Bi), atomic radius increases down the group. As principal energy levels (shells) add, valence electrons are farther from the nucleus, reducing the attractive force between valence electrons and the nucleus, which allows the radius to expand.
2. K has one valence electron (4s¹) and Ca has two (4s²). K’s valence electron experiences lower effective nuclear charge than Ca’s, making it easier to remove, so first ionization energy of K is lower.
3. Down the alkaline earth metals group, more electron shells add. Valence electrons are farther from the nucleus (greater average distance), weakening nuclear attraction, so first ionization energy decreases.
4. First ionization energy increases across a period (left to right) and decreases down a group. Be (Group 2, Period 2) has higher ionization energy than Li (Group 1, Period 2), Na (Group 1, Period 3), and Mg (Group 2, Period 3).
5. K is in Period 4 (valence electrons in 4s) and Br is in Period 4, but K has a lower effective nuclear charge than Br. Lower effective nuclear charge means weaker attraction for valence electrons, so K has a larger atomic radius.

Answer:

1. C
2. C
3. C
4. A
5. D