Question

activity b (continued from previous page)5. count: review the lewis diagrams you drew on the previous page. note that each element tends to form a certain number of chemical bonds. this value is the valence of the element.for each element in the table below, use the gizmo to find the number of valence electrons and the list the valence based on the lewis diagram. then find the sum of these numbers.| element | symbol | # of valence electrons | valence | sum || ---- | ---- | ---- | ---- | ---- || fluorine | f | 7 | 1 | 8 || hydrogen | h | 1 | 1 | 2 || oxygen | o | 6 | 2 | 8 || nitrogen | n | 5 | 3 | 8 || chlorine | cl | 7 | 1 | 8 || carbon | c | 4 | 4 | 8 |make a rule: if you knew the number of valence electrons in a nonmetal atom, how would you determine the valence of the element? (hint: ignore hydrogen for now.)

Explanation:

Step1: Recall valence electron rules

• For main group elements: Valence electrons = group number (for groups 1-2, 13-18). Hydrogen (group 1): 1 valence electron, Fluorine (group 17):7, Oxygen (group16):6, Nitrogen (group15):5, Chlorine (group17):7, Carbon (group14):4.

Step2: Define valence for nonmetals

Valence = 8 - number of valence electrons (except H, valence=1, since it fills 2 electrons max).

Step3: Calculate sum (valence + valence electrons)

Sum = valence electrons + valence
---

Hydrogen (H):

Step1: Valence electrons (group1)

$1$

Step2: Valence (H fills 2 e⁻)

$1$

Step3: Sum

$1+1=2$
---

Fluorine (F):

Step1: Valence electrons (group17)

$7$

Step2: Valence ($8-7$)

$1$

Step3: Sum

$7+1=8$
---

Oxygen (O):

Step1: Valence electrons (group16)

$6$

Step2: Valence ($8-6$)

$2$

Step3: Sum

$6+2=8$
---

Nitrogen (N):

Step1: Valence electrons (group15)

$5$

Step2: Valence ($8-5$)

$3$

Step3: Sum

$5+3=8$
---

Chlorine (Cl):

Step1: Valence electrons (group17)

$7$

Step2: Valence ($8-7$)

$1$

Step3: Sum

$7+1=8$
---

Carbon (C):

Step1: Valence electrons (group14)

$4$

Step2: Valence ($8-4$)

$4$

Step3: Sum

$4+4=8$
---

Rule for nonmetals (excl. H):

Step1: Relate valence to valence e⁻

Valence = $8 - \text{valence electrons}$

Answer:

Element	Symbol	# of valence electrons	Valence	Sum
Fluorine	F	7	1	8
Oxygen	O	6	2	8
Nitrogen	N	5	3	8
Chlorine	Cl	7	1	8
Carbon	C	4	4	8

Rule: For a nonmetal atom (excluding hydrogen), valence = $8 - \text{number of valence electrons}$ (this ensures the atom can gain/share electrons to reach a full 8-electron outer shell).