Question

exit ticket
for each of the following, draw the lewis diagrams, predicted formula for each, and the name of the ionic compound that would be formed.

elements	lewis diagrams of the compound	predicted formula	name of ionic compound
2. calcium & oxygen

1. *the chemical formula for lithium oxide is __.

a. lio (b) li₂o (c) lio₂ (d) li₂o₃

1. what is the correct formula of iron (ii) chloride?

(a) fecl (b) fecl₂ (c) fe₂cl (d) fecl₃

1. what is the correct lewis dot structure for a neutral atom of arsenic?

a.

..

• as *

..

b.

..

• as *

.

c.

..

• at *

.

d.

..
: ar :
..

Explanation:

Question 3

Step1: Determine ion charges

Lithium (Li) is in Group 1, so it forms \( \text{Li}^+ \) ions. Oxygen (O) is in Group 16, so it forms \( \text{O}^{2-} \) ions.

Step2: Balance charges

To form a neutral compound, the total positive charge must equal the total negative charge. Let the number of \( \text{Li}^+ \) be \( x \) and \( \text{O}^{2-} \) be \( y \). Then \( x(+1) + y(-2) = 0 \), so \( x = 2y \). Using the smallest whole numbers, \( x = 2 \), \( y = 1 \). Thus, the formula is \( \text{Li}_2\text{O} \).

Step1: Determine ion charges

Iron (II) means \( \text{Fe}^{2+} \) (since the Roman numeral II indicates a +2 charge). Chloride is \( \text{Cl}^- \) (from Group 17, so -1 charge).

Step2: Balance charges

Let the number of \( \text{Fe}^{2+} \) be \( x \) and \( \text{Cl}^- \) be \( y \). Then \( x(+2) + y(-1) = 0 \), so \( 2x = y \). Using the smallest whole numbers, \( x = 1 \), \( y = 2 \). Thus, the formula is \( \text{FeCl}_2 \).

Step1: Determine valence electrons

Arsenic (As) is in Group 15, so it has 5 valence electrons. A Lewis dot structure shows valence electrons as dots around the symbol.

Step2: Analyze options

• Option a: Has 5 valence electrons (2 paired, 3 unpaired) around As, which matches.
• Option b: Has 4 valence electrons (incorrect, As has 5).
• Option c: Shows At (Astatine), not As (incorrect symbol).
• Option d: Shows Ar (Argon), not As (incorrect symbol).

Answer:

B. \( \text{Li}_2\text{O} \)

Question 4