Question

free response questions
answer the following questions related to k.
(a) in terms of atomic structure, explain why the atomic radius of k is larger than that of na.
(b) in terms of atomic structure, explain why the first - ionization energy of k is less than that of ca.
ionization energy is the minimum energy required to remove an electron
(c) k forms the compound k₂o, which is an ionic compound that is brittle. identify another element, m, that is likely to form a brittle, ionic compound with the formula m₂o. justify your answer in terms of periodic trends.

Explanation:

(a) Potassium (K) has an additional electron - shell compared to sodium (Na). As the number of electron - shells increases, the outermost electrons are further from the nucleus, resulting in a larger atomic radius for K.
(b) Potassium has one valence electron in its 4s orbital, while calcium has two. Calcium has a higher effective nuclear charge due to more protons in the nucleus and the same shielding effect from inner - shell electrons. So, it is harder to remove an electron from Ca, making its first - ionization energy higher than that of K.
(c) Sodium (Na) is likely to form a brittle, ionic compound with the formula $Na_2O$. Sodium is in the same group as potassium. Elements in the same group have similar chemical properties. Both Na and K are alkali metals with one valence electron, and they readily lose this electron to form a + 1 ion. When they react with oxygen, they form ionic compounds with a 2:1 metal - to - oxygen ratio, and these ionic compounds are typically brittle due to the strong electrostatic forces between ions and the way they break along planes of weakness.

Answer:

(a) K has an extra electron - shell, increasing atomic radius.
(b) Ca has higher effective nuclear charge, making its first - ionization energy higher.
(c) Na. It's in the same group as K, has similar chemical properties and forms a 2:1 ionic compound with O.