5. write the number of outer most electrons for each element. na____ mg____ al____ si____ p____ s____ cl____…

Explanation:

Step1: Recall electron - configuration rules

Elements in the same period have electrons filling the same principal energy level. The number of valence (outer - most) electrons can be determined from their group number in the periodic table (for main - group elements).

Step2: Determine valence electrons for Na

Sodium (Na) is in Group 1. So, it has 1 outer - most electron.

Step3: Determine valence electrons for Mg

Magnesium (Mg) is in Group 2. So, it has 2 outer - most electrons.

Step4: Determine valence electrons for Al

Aluminum (Al) is in Group 13. So, it has 3 outer - most electrons.

Step5: Determine valence electrons for Si

Silicon (Si) is in Group 14. So, it has 4 outer - most electrons.

Step6: Determine valence electrons for P

Phosphorus (P) is in Group 15. So, it has 5 outer - most electrons.

Step7: Determine valence electrons for S

Sulfur (S) is in Group 16. So, it has 6 outer - most electrons.

Step8: Determine valence electrons for Cl

Chlorine (Cl) is in Group 17. So, it has 7 outer - most electrons.

Step9: Determine valence electrons for Ar

Argon (Ar) is in Group 18. So, it has 8 outer - most electrons.

Answer:

Na: 1, Mg: 2, Al: 3, Si: 4, P: 5, S: 6, Cl: 7, Ar: 8