select the correct answer. which of these pairs of elements have the same number of valence electrons? a…

select the correct answer. which of these pairs of elements have the same number of valence electrons? a. phosphorus (p) and chlorine (cl) b. berylium (be) and calcium (ca) c. chlorine (cl) and helium (he) d. oxygen (o) and carbon (c)

select the correct answer. which of these pairs of elements have the same number of valence electrons? a. phosphorus (p) and chlorine (cl) b. berylium (be) and calcium (ca) c. chlorine (cl) and helium (he) d. oxygen (o) and carbon (c)

Answer

Explanation:

Step1: Determine valence - electrons of P

Phosphorus (P) is in group 15. It has 5 valence electrons.

Step2: Determine valence - electrons of Cl

Chlorine (Cl) is in group 17. It has 7 valence electrons. So, A is incorrect.

Step3: Determine valence - electrons of Be

Beryllium (Be) is in group 2. It has 2 valence electrons.

Step4: Determine valence - electrons of Ca

Calcium (Ca) is in group 2. It has 2 valence electrons. So, B is correct.

Step5: Determine valence - electrons of Cl

Chlorine (Cl) has 7 valence electrons.

Step6: Determine valence - electrons of He

Helium (He) is a noble gas with 2 valence electrons (it has a full outer - shell with 2 electrons). So, C is incorrect.

Step7: Determine valence - electrons of O

Oxygen (O) is in group 16. It has 6 valence electrons.

Step8: Determine valence - electrons of C

Carbon (C) is in group 14. It has 4 valence electrons. So, D is incorrect.

Answer:

B. beryllium (Be) and calcium (Ca)