Covalent bonds form when atoms share valence electrons in order to achieve a full outer shell and attain greater stability. In the case of the sugar compound glucose (C6H12O6), we can look at the structures of carbon, hydrogen, and oxygen atoms to understand how these bonds are formed.
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Valence Electrons of Carbon, Oxygen, and Hydrogen:
- Carbon (C): Has 4 valence electrons. It needs 4 more electrons to fill its outer shell (total shell capacity is 8), which makes it tetravalent and capable of forming four covalent bonds.
- Hydrogen (H): Has 1 valence electron. Each hydrogen atom needs 1 more electron to fill its outer shell (which can hold 2 electrons), making it monovalent and capable of forming one covalent bond.
- Oxygen (O): Has 6 valence electrons. It needs 2 more electrons to fill its outer shell, making it divalent and capable of forming two covalent bonds.
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Bond Formation:
- In glucose, the carbon atoms (C) form covalent bonds with each other and with hydrogen (H) and oxygen (O) atoms. A carbon atom will share its valence electrons with another atom that has an available valence electron, creating a stable full outer shell configuration through these shared pairs of electrons.
- Each carbon atom can form single bonds with hydrogen atoms, each sharing one of their valence electrons with hydrogen.
- In glucose, there are 6 carbon atoms that can bond with a total of 12 hydrogen atoms (since each carbon shares four of its electrons with four hydrogen atoms) and 6 oxygen atoms which typically bond with carbon in the form of hydroxyl (-OH) groups and a carbonyl (C=O) group in the cyclic form.
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Structure of Glucose:
- Glucose can be represented as a carbon backbone with hydroxyl groups (-OH) attached, as well as an aldehyde group (or a ketone group in the ring form).
- Each carbon atom is bonded to either hydrogen or oxygen through shared electrons, resulting in a stable molecular structure. The covalent bonding allows glucose to be a stable compound with unique properties, such as solubility in water.
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Summary: Covalent bonds in glucose form through the sharing of valence electrons among carbon, oxygen, and hydrogen atoms. Carbon shares its four electrons to bond with four other atoms, while oxygen shares its two, and hydrogen shares its one, creating a stable compound essential for biological processes. Overall, the shared pairs of electrons establish strong bonds that make up the molecular structure of glucose.