Question

hanging together: building molecules
atoms come together to make extended structures called molecules. a formula known as a molecular formula can be written to show what atoms it contains. today you will determine the molecular formulas for a number of molecules.
a) read the chemical names and look at the images below.
b) identify the elements in order of the molecular formula.
c) write the molecular formula for each molecule.

1. hydrogen chloride
2. carbon dioxide
3. phosphorus pentoxide
4. water

Explanation:

Step1: Analyze Hydrogen Chloride

• Element Name: Hydrogen, Element Symbol: H, How Many: 1
• Element Name: Chlorine, Element Symbol: Cl, How Many: 1
• Molecular Formula: HCl

Step2: Analyze Carbon Dioxide

• Element Name: Carbon, Element Symbol: C, How Many: 1
• Element Name: Oxygen, Element Symbol: O, How Many: 2
• Molecular Formula: CO₂

Step3: Analyze Phosphorus Pentoxide

• Element Name: Phosphorus, Element Symbol: P, How Many: 2
• Element Name: Oxygen, Element Symbol: O, How Many: 5
• Molecular Formula: P₂O₅

Step4: Analyze Water

• Element Name: Hydrogen, Element Symbol: H, How Many: 2
• Element Name: Oxygen, Element Symbol: O, How Many: 1
• Molecular Formula: H₂O

Answer:

1)

Element Name	Element Symbol	How Many?
Chlorine	Cl	1

Molecular Formula: HCl

2)

Element Name	Element Symbol	How Many?
Oxygen	O	2

Molecular Formula: CO₂

3)

Element Name	Element Symbol	How Many?
Oxygen	O	5

Molecular Formula: P₂O₅

4)

Element Name	Element Symbol	How Many?
Oxygen	O	1

Molecular Formula: H₂O