Why are the water molecule bonds at an angle and not straight like the CO2?
The reason why the water molecule (H2O) bonds are at an angle instead of being straight like carbon dioxide (CO2) is due to the difference in the molecular shape and arrangement of the atoms.
Water molecule consists of two hydrogen atoms bonded to an oxygen atom. The oxygen atom has 6 valence electrons, while each hydrogen atom contributes 1 valence electron. The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable arrangement of 8 valence electrons.
In order for the oxygen atom to achieve an octet, it needs to share two pairs of electrons. This means that two hydrogen atoms will form covalent bonds with the oxygen atom. These bonds are formed by sharing a pair of electrons, creating two bonds between the oxygen and each hydrogen atom.
Additionally, oxygen is more electronegative than hydrogen, meaning it attracts the shared electrons more strongly. This causes the oxygen atom to pull the electron pairs closer towards itself, creating a slight negative charge near the oxygen atom and a slight positive charge near the hydrogen atoms.
The arrangement of these bonds and the resulting charge distribution give rise to the bent shape of the water molecule. The oxygen atom and its two hydrogen atoms are not in a straight line, but rather form an angle of approximately 104.5 degrees. This angle allows the electron pairs to stay as far apart from each other as possible, reducing electron-electron repulsion and promoting stability.
On the other hand, carbon dioxide molecule consists of one carbon atom bonded to two oxygen atoms. The carbon atom has 4 valence electrons, while each oxygen atom contributes 6 valence electrons. In this case, each oxygen atom forms a double bond with the carbon atom by sharing two pairs of electrons. As a result, the carbon-oxygen bonds are linear with a bond angle of 180 degrees.
In summary, the difference in the molecular shape and electron distribution between water and carbon dioxide molecules is responsible for the bent and linear bond angles, respectively.