Simple Chemical Reactions Unit Test
12 of 1912 of 19 Items
Question
Use the electronegativity and valence electron information to answer the question.
H electronegativity: 2.2
H valence electrons: 1
C electronegativity: 2.55
C valence electrons: 4
O electronegativity: 3.44
O valence electrons: 6
Chemical weathering over hundreds of thousands of years formed modern caves. One form of chemical weathering occurs when carbon dioxide reacts with water to produce carbonic acid, H2CO3. How many bonds formed in H2CO3?
(1 point)
Responses
three
three
six
six
five
five
eight
eight
To determine the number of bonds formed in H2CO3, we need to know the number of valence electrons each element contributes and their electronegativity.
In H2CO3, we have:
- 2 hydrogen atoms (H) with 1 valence electron each
- 1 carbon atom (C) with 4 valence electrons
- 3 oxygen atoms (O) with 6 valence electrons each
To form bonds, each atom needs to fulfill the octet rule, which states that atoms tend to gain, lose, or share electrons in order to have a full outer shell of 8 electrons. However, hydrogen atoms can only hold 2 electrons in their outer shell.
Since each oxygen atom needs 2 electrons to complete its octet (since it already has 6 valence electrons), it will form a double bond with the carbon atom, which contributes 4 electrons.
To determine the total number of bonds formed, we need to divide the remaining electrons (after considering double bonds) by 2 since each bond consists of 2 electrons.
Calculating the remaining electrons:
- Hydrogen needs 2 electrons for a full outer shell, so it contributes 0 electrons (2 - 2 = 0)
- Carbon forms a double bond with each oxygen atom, using 4 electrons (4 * 2 = 8)
- Each oxygen atom contributes 2 electrons to its double bond with carbon (2 * 3 = 6)
Adding up the remaining electrons: 0 + 8 + 6 = 14
Dividing the remaining electrons by 2 to determine the number of bonds: 14 / 2 = 7
Therefore, the number of bonds formed in H2CO3 is seven.