ch 3 periodicity

Question 1

define periodicity

Answer 1

properties of elements recurring with increasing atomic number

Question 2

explain why the atomic radius of Na is larger than its ion, while the atomic radius of Cl is smaller than its ion.

Answer 2

1. Na and Na+ have the same number of protons, and Cl and Cl- have the same number of protons.
2. Na occupies one more electron and electron shell than Na+, while Cl- has one more electron while occupying the same number of electron shells as Cl.
3. Na experiences a weaker nuclear attraction
4. Cl experiences a stronger nuclear attraction

Question 3

explain why reactivity of group I elements increase down the group.

Answer 3

1. as the atomic radius of elements increase down the group, the nuclear attraction faced by valence electrons decreases
2. removing the valence electron requires lesser energy down the group
3. since group I elements form ions by losing electrons

Question 4

explain why the reactivity of group 17 elements decrease down the group.

Answer 4

1. as the atomic radius of elements increase down the group, the nuclear attraction faced by valence electrons decreases
2. neighboring electrons will face a weaker attraction
3. since group 17 elements form ions by gaining electrons

Question 5

explain why transition metal compounds are colored.

Answer 5

1. transition metals have incompletely-filled d-orbitals
2. when ligands are bonded to the TM, causes d-orbitals to split into two levels
3. electrons absorb visible light and is excited from low to high energy level
4. the displayed color is complementary to the light absorbed