Chapter 1 The Outsiders S.E. Hinton

Biochemistry Worksheet 1. Why is water such an important molecule to living things? Water is crucial for life on Earth due to its unique properties. It serves as a solvent for biochemical reactions, provides a medium for metabolic processes, regulates temperature, transports nutrients and waste, and participates in many other biological functions 2. Describe the chemical make up and type of bonding found in water molecules. The chemical makeup of a water molecule (H2O) consists of two hydrogen atoms covalently bonded to one oxygen atom. The type of bonding found in water molecules is polar covalent bonding 3. Explain why the hydrogen and oxygen atoms don't share electrons equally in a water molecule. In a water molecule, oxygen is more electronegative than hydrogen, meaning it attracts electrons more strongly. This causes the shared electrons in the O-H bonds to be pulled closer to the oxygen atom, resulting in an uneven distribution of charge within the molecule 4. What is the effect of this uneven sharing of electrons in water? The uneven sharing of electrons in a water molecule results in a polarity, with the oxygen atom carrying a partial negative charge (δ-) and the hydrogen atoms carrying partial positive charges (δ+). This polarity gives water its unique properties, such as its ability to form hydrogen bonds and dissolve many substances 5. Sketch a molecule of water showing the charges on the molecule. 6. What is the overall charge on a water molecule? Explain why. The overall charge on a water molecule is neutral because the positive charges from the hydrogen atoms balance out the negative charge from the oxygen atom 7. Define polar compound and give an example. A polar compound is a molecule that has a partial positive charge on one end and a partial negative charge on the other due to differences in electronegativity. An example of a polar compound is ammonia (NH3) 8. Water's polarity makes it very effective in _ dissolving_ other substances. 9. Name 2 types of compounds that dissolve well in water. Two types of compounds that dissolve well in water are ionic compounds (e.g., sodium chloride) and polar covalent compounds (e.g., sugars) 10. What happens when an ionic compound such as sodium chloride (table salt) dissolves in water? When an ionic compound such as sodium chloride dissolves in water, the water molecules surround the individual ions, separating them from each other and allowing them to disperse throughout the solution 11. Water molecules are __ attracted ___ to other water molecules. 12. What type of bonding holds 2 or more water molecules together? Hydrogen bonds hold two or more water molecules together 13. Are hydrogen bonds strong or weak bonds? Can they be easily broken? Hydrogen bonds are relatively weak bonds compared to covalent or ionic bonds, but they can still have a significant effect on the properties of substances. They can be broken relatively easily under certain conditions 14.Water molecules attracting other water molecules is called cohesion_____. 15. Cohesion of water molecules produces ____ surface _____ tension making water seem like it has a "skin" on it. Surface tension enables some ___ small organisms___ to walk across the surface of the water. 16. Water molecules attracting other types of molecules is called ________ adhesion_______. 17. Adhesion and cohesion together enable water molecules to move _________ upward ___ through narrow tubes against the force of gravity. 18. The above property of water is called _____ capillarity______. 19. Give an example of an organism using capillarity. An example of an organism using capillarity is a plant drawing water from the soil through its roots and transporting it to its leaves for photosynthesis 20. What must be true for water to change temperature? For water to change temperature, energy must be added or removed from the system, causing the kinetic energy of the water molecules to increase or decrease 21. What effect does heating water have on the hydrogen bonds holding the water molecules together? What happens to the speed at which the molecules are moving? Heating water breaks the hydrogen bonds holding the water molecules together, allowing them to move more freely. This increases the speed at which the molecules are moving, resulting in an increase in temperature 22. Give an example of how this water property helps organisms in the environment. This property of water helps organisms in the environment by regulating temperature and providing a stable habitat for aquatic life, preventing drastic temperature fluctuations