Question

calcium (ca) is predicted to have a reactivity than potassium (k) and a reactivity than magnesium (mg). this is because the nucleus of a calcium atom attracts its valence electrons strongly than the nucleus of a potassium atom but strongly than the nucleus of a magnesium atom.

Explanation:

Step1: Recall periodic - table trends

Reactivity of metals increases down a group and decreases across a period. Potassium is in Group 1 and Period 4, calcium is in Group 2 and Period 4, and magnesium is in Group 2 and Period 3.

Step2: Compare reactivity with potassium

Since calcium is to the right of potassium in the same period, calcium has a smaller atomic radius and a stronger nuclear - attraction for valence electrons, so it is less reactive than potassium.

Step3: Compare reactivity with magnesium

Since calcium is below magnesium in the same group, calcium has a larger atomic radius and a weaker nuclear - attraction for valence electrons compared to magnesium, so it is more reactive than magnesium.

Step4: Analyze nuclear - attraction

The nucleus of a calcium atom attracts its valence electrons more strongly than the nucleus of a potassium atom because calcium has more protons in the nucleus and a smaller atomic radius in the same period. But it attracts its valence electrons less strongly than the nucleus of a magnesium atom because calcium has an additional electron shell.

Answer:

Less; More; More; Less