Understanding Valency in Elements and Compound Formation

What is valency in chemistry?

• The weight of an element

• The color of an element

• Combining power of an element

• The boiling point of an element

Answer explanation

Valency in chemistry refers to the combining power of an element, indicating the number of bonds it can form with other elements.

How is valency determined for elements?

• Based on the color of the element

• By the number of protons in the nucleus

• According to the atomic mass of the element

• Based on the number of electrons an element needs to gain, lose, or share to achieve a full outer shell.

Answer explanation

Valency is determined based on the number of electrons an element needs to gain, lose, or share to achieve a full outer shell.

What is the valency of sodium in NaCl?

• -1

• 2

• 0

• +1

Answer explanation

The valency of sodium in NaCl is +1 because sodium is a group 1 element and tends to lose one electron to achieve a stable electron configuration.

How does valency affect chemical bonding?

• Valency affects chemical bonding by determining the number of bonds an atom can form and the type of bonds it can participate in.

• Valency determines the color of the compound formed

• Valency has no impact on chemical bonding

• Valency affects the physical state of the compound

Answer explanation

Valency affects chemical bonding by determining the number of bonds an atom can form and the type of bonds it can participate in.

Determine the valency of chlorine in HCl.

• 2

• 3

• 4

• 1

Answer explanation

The valency of chlorine in HCl is 1 because chlorine typically has a valency of 1 when it forms a compound with hydrogen.

Select all the scenarios below where we encounter elements with valency=2.

• Methane (CH4)

• Sodium chloride (NaCl)

• Water (H2O)

• Carbon dioxide (CO2)

Answer explanation

Elements with valency=2 typically form compounds with other elements. In this case, water (H2O) and carbon dioxide (CO2) are examples where we encounter elements with valency=2.

Calculate the valency of nitrogen in NH3.

• 4

• 3

• 1

• 2

Answer explanation

The valency of nitrogen in NH3 is 3 because nitrogen has 5 valence electrons and forms 3 covalent bonds with hydrogen atoms to complete its octet.

Select all examples from below where we find polyvalent (Valency of 3 or more) elements.

• FeCl3 (Iron(III) Chloride)

• CO2 (Carbon Dioxide)

• NaCl (Sodium Chloride)

• H2O (Water)

Answer explanation

FeCl3 (Iron (III) Chloride) and CO2 (Carbon Dioxide) are examples of polyvalent elements with a valency of 3 or more.

Fe has valency of 3 and C has valency of 4