Question

1. decide if the following are an element, elemental molecule, or a compound.

a. so₄
b. o₂
c. c₆h₁₂o₆
d. mg₄o₂
e. li
f. n₂
g. hg
h. ch₃oh
i. h₂
j. pb(no₃)₂
k. cl₂
l. tl
m. k
n. h₃po₃
o. clo⁻
p. o₃

1. using only letters and subscripts, write the formula for the following molecules

a.
b.
c.
d.
e.
f.

Explanation:

Step1: Recall definitions

An element is a pure substance made of only one type of atom. An elemental molecule consists of two or more atoms of the same element. A compound is a substance made of two or more different - types of atoms chemically combined.

Step2: Analyze each substance in part 3

a. SO₄

It is a poly - atomic ion (sulfate ion). It is a compound as it has sulfur and oxygen atoms.

b. O₂

It is an elemental molecule since it consists of two oxygen atoms (same element).

c. C₆H₁₂O₆

It is a compound as it contains carbon, hydrogen, and oxygen atoms.

d. Mg₄O₂

It is a compound with magnesium and oxygen atoms.

e. Li

It is an element (lithium).

f. N₂

It is an elemental molecule with two nitrogen atoms.

g. Hg

It is an element (mercury).

h. CH₃OH

It is a compound with carbon, hydrogen, and oxygen atoms.

i. H₂

It is an elemental molecule with two hydrogen atoms.

j. Pb(NO₃)₂

It is a compound with lead, nitrogen, and oxygen atoms.

k. Cl₂

It is an elemental molecule with two chlorine atoms.

l. Tl

It is an element (thallium).

m. K

It is an element (potassium).

n. H₃PO₃

It is a compound with hydrogen, phosphorus, and oxygen atoms.

o. ClO⁻

It is a poly - atomic ion (hypochlorite ion), a compound.

p. O₃

It is an elemental molecule with three oxygen atoms.

Step3: Write formulas for part 4

a.

The diagram shows three oxygen atoms bonded together, so the formula is O₃.

b.

The diagram shows two hydrogen atoms bonded together, so the formula is H₂.

c.

The diagram shows two hydrogen atoms and one oxygen atom, so the formula is H₂O.

d.

The diagram shows one carbon atom and four hydrogen atoms, so the formula is CH₄.

e.

The diagram shows one carbon atom and two oxygen atoms, so the formula is CO₂.

f.

The diagram shows six carbon atoms and six hydrogen atoms, so the formula is C₆H₆.

Answer:

3.
a. Compound
b. Elemental molecule
c. Compound
d. Compound
e. Element
f. Elemental molecule
g. Element
h. Compound
i. Elemental molecule
j. Compound
k. Elemental molecule
l. Element
m. Element
n. Compound
o. Compound
p. Elemental molecule
4.
a. O₃
b. H₂
c. H₂O
d. CH₄
e. CO₂
f. C₆H₆