Question

1. Which alkali metal has 3 electron shells?

A) Lithium
B) Sodium
C) Potassium
D) Rubidium
2. What is the mass # of an atom w 15 protons, 18 electrons, and 17 neutrons?
3. Which element has 6 valence electrons and 3 electron shells?

A) Sodium
B) Potassium
C) Chlorine
D) Phosphorus

Answer 1

Sodium is the alkali metal with 3 electron shells, the atom described has a mass number of 32, and chlorine is the element with 6 valence electrons in 3 electron shells.Correct answer is option A

Step-by-step explanation:

The alkali metal that has 3 electron shells is sodium (Na). Sodium has an atomic number of 11, which means it has 11 protons and 11 electrons when neutral. Therefore, the first two electron shells will be filled (2 electrons in the first shell and 8 in the second shell), with one electron in the third shell, giving it 3 electron shells in total. The mass number of an atom is equal to the sum of its protons and neutrons. For an atom with 15 protons and 17 neutrons, the mass number would be 15 + 17 = 32.

The element that has 6 valence electrons and occupies 3 electron shells is chlorine (Cl). Chlorine, with an atomic number of 17, fills its first two shells (2 in the first shell and 8 in the second) and places the remaining 7 electrons in the third shell. Six of these are valence electrons.