Question

1. which of the following is/are metalloid(s)?

a. i and ii only
b. i and iii only
c. ii and iii only
d. i, ii, and iii
i. silicon
ii. boron
iii. neon

Explanation:

Question 3: Completing the Table

To solve this, we use the following relationships:

• Atomic # = #p⁺ = #e⁻ (for neutral atoms)
• Mass # = #p⁺ + #n⁰
• Group # relates to valence electrons (e.g., Group 1 has 1 valence e⁻, Group 15 has 5, Group 18 has 8).
• Period # is the row number (Li is in Period 2, etc.).

Row 1: Li (Lithium)

• Atomic # = 3 (Li’s atomic number is 3)
• #p⁺ = 3 (atomic # = #p⁺)
• #e⁻ = 3 (neutral, so #e⁻ = #p⁺)
• Mass # = 3 (p⁺) + 4 (n⁰, typical Li isotope) = 7
• Group # = 1 (valence e⁻ = 1)
• Period # = 2 (Li is in Period 2)

Row 2: Element with #e⁻ = 15 (neutral, so #p⁺ = 15)

• Atomic # = 15 (Phosphorus, P)
• #p⁺ = 15
• Mass # = 31 (given), so #n⁰ = 31 - 15 = 16
• Group # = 15 (valence e⁻ = 5)
• Period # = 3 (P is in Period 3)

Row 3: Group 18, Period 3

• Group 18 elements have 8 valence e⁻.
• Period 3, Group 18: Argon (Ar)
• Atomic # = 18 (Ar’s atomic number)
• #p⁺ = 18
• #e⁻ = 18 (neutral)
• Mass # = 18 (p⁺) + 22 (n⁰, typical Ar isotope) = 40 (or 39/40; we use 40 for simplicity)
• #n⁰ = 40 - 18 = 22

Filled Table:

ELEMENT	Atomic #	Mass #	#p⁺	#n⁰	#e⁻	GROUP #	PERIOD #	# OF VALENCE e⁻
P	15	31	15	16	15	15	3	5
Ar	18	40	18	22	18	18	3	8

Question 4: Identifying Metalloids

Metalloids have properties of both metals and nonmetals. Common metalloids: B, Si, Ge, As, Sb, Te, Po, At.

• I. Silicon (Si): Metalloid.
• II. Boron (B): Metalloid.
• III. Neon (Ne): Noble gas (nonmetal), not a metalloid.

Thus, I (Si) and II (B) are metalloids.

Question 4 Answer:

Silicon (I) and boron (II) are metalloids. Neon (III) is a noble gas (nonmetal). So only I and II are metalloids.

Answer:

A. I and II only