Molecular Compounds

Question 1

What are molecular compounds?

Answer 1

Molecular compounds are composed of only non-metallic atoms.

• The non-metals are held together by covalent bonds.
• Covalent bonds involve the “sharing” of electrons between the atoms involved in the compound.
• The simultaneous attraction of electrons between the nuclei of adjacent atoms results in the covalent bonds.
• Made up of non-metals, no charged species are involved.

Question 2

When naming binary molecular compounds we use a system of prefixes.

Answer 2

-Subscript:1
Prefix:Mono
-Subscript:2
Prefix:Di
-Subscript:3
Prefix: Tri
-Subscript:4
Prefix:Tetra
-Subscript:5
Prefix: Pentra
-Subscript:6
Prefix: Hexa
-Subscript:7
Prefix: Hepta
-Subscript:8
Prefix: Octa
-Subscript:9
Prefix:Nona
-Subscript:10
Prefix: Deca

Question 3

How do you write covalent compound formulas?

Answer 3

1. Write the chemical symbol for the first element in the name.
2. Write the appropriate subscript according to the prefix given in the name.
3. Repeat steps 1 and 2 for the second element.

Question 4

How do you name covalent compounds?

Answer 4

1. Look at the subscript on the first atom; write the proper prefix(Mono is not used as a prefix on the first atom in the compound).
2. Write the name of the first atom as all one word with the prefix.
3. Repeat steps 1 and 2 for the second atom, except here the ending of the name if “ide”.

Question 5

Why do some molecular compounds need to be memorized?

Answer 5

They do not follow the prefix rule.

Question 6

What is the memorized “formula of molecule” for propane?

Answer 6

C3H8(g)

Question 7

What is the memorized “formula of molecule” for methane?

Answer 7

CH4(g)

Question 8

What is the memorized “formula of molecule” for methanol?

Answer 8

CH3OH(l)

Question 9

What is the memorized “formula of molecule” for ethane?

Answer 9

C2H6(g)

Question 10

What is the memorized “formula of molecule” for ethanol(ethyl acid)?

Answer 10

C2H5OH(l)

Question 11

What is the memorized “formula of molecule” for acetic acid(ethanoic acid)(vinegar)?

Answer 11

CH3CooH(aq)

Question 12

What is the memorized “formula of molecule” for ammonia?

Answer 12

NH3(g)

Question 13

What is the memorized “formula of molecule” for glucose?

Answer 13

C6H12O6(s)

Question 14

What is the memorized “formula of molecule” for hydrogen sulfide?

Answer 14

H2S(g)

Question 15

What is the memorized “formula of molecule” for ozone?

Answer 15

O3(g)

Question 16

What is the memorized “formula of molecule” for sucrose?

Answer 16

C12H22O11(s)

Question 17

What is the memorized “formula of molecule” for water?

Answer 17

H2O(l)

Question 18

What is the memorized “formula of molecule” for hydrogen peroxide?

Answer 18

H2O2(l)

Question 19

There are a number of elements on the periodic table that are never found by themselves in nature.

Answer 19

• H1(g): hydrogen
• F2(g): fluorine
• I2(s): iodine
• O2(g): oxygen
• Cl2(g): chlorine
• At2(s): astatine
• N2(g): nitrogen
• Br2(l): bromine

Question 20

There are two more elements that are never found alone in nature, however, these elements are found as a quartet and octet.

Answer 20

• P4: phosphorus

- S8: sulphur

Question 21

What are the properties of molecular compounds?

Answer 21

• Share electrons.
• Covalent bonds.
• Non-metal bonded to non-metal.
• molecules exist as individual packages.
• s, l or g at room temperature.
• Usually will not conduct electricity in solution (Non-electrolytes).
• When naming use prefixes.

Question 22

How can you tell the difference between an ionic compound and a covalent compound?

Answer 22

Ionic has a metal and non-metal bond. Covalent has 2 non-metal bonds. Covalent don’t conduct in solutions.

Question 23

A substance that conducts electricity in solution is called an _______, while a substance that does not conduct electricity in solution is called a _______.

Answer 23

Electrolyte, non-electrolyte.