Water

• What chemical reaction is depicted in the image?

  $2H +$$O \rightarrow H₂O$

  
• What type of chemical bond is formed between hydrogen and oxygen atoms in water?

  Covalent bonds

  
• Why do hydrogen and oxygen atoms form covalent bonds instead of ionic bonds?

  Because hydrogen and oxygen share electrons rather than one atom completely losing and the other gaining electrons

  
• How many covalent bonds does each oxygen atom form in water?

  Two

  
• How many electrons are involved in a covalent bond between hydrogen and oxygen?

  Two

  
• What determines the geometry of the water molecule?

  The arrangement of electron pairs around the central oxygen atom

  
• What functional group is represented by the structure shown?

  Hydrogen bond

  
• How does the hydrogen bond network influence the physical properties of water?

  • High boiling point: due to strong hydrogen bonds requiring more energy to break
  • High melting point: similar to boiling point, strong bonds resist melting
  • High surface tension: hydrogen bonds create a cohesive film on the surface
  • Excellent solvent: ability to form hydrogen bonds with polar molecules

  
• What are the key characteristics of hydrogen bonds?

  • Attraction between a partially positive hydrogen atom and a partially negative atom of another molecule
  • Involves hydrogen bonded to highly electronegative atoms such as oxygen, nitrogen, or fluorine
  • Non-covalent bonds, weaker than covalent bonds

  
• Why is water an effective solvent for polar substances?

  Because it can form hydrogen bonds with polar molecules, allowing them to disperse effectively

  
• How do hydrogen bonds contribute to the high boiling point of water?

  Hydrogen bonds between water molecules create a strong cohesive network that requires a significant amount of energy to overcome, leading to a high boiling point

  
• What would be the effect of reducing the strength of hydrogen bonds in water?

  Reducing hydrogen bond strength would likely result in:

  • Lowered boiling and melting points
  • Decreased surface tension
  • Reduced solvency for polar molecules

  
• What atoms typically participate in hydrogen bonding?

  Oxygen, nitrogen, or fluorine

  
• What is the difference between a covalent bond and a hydrogen bond?

  • Covalent bonds involve the sharing of electrons between atoms, forming strong chemical links
  • Hydrogen bonds are non-covalent attractions between a partially positive hydrogen and a partially negative atom, forming weaker links

  
• What is the polarity of the water molecule?

  The water molecule is polar because of the electronegativity difference between oxygen and hydrogen, resulting in a partial negative charge on oxygen and partial positive charges on hydrogen atoms

  
• How many hydrogen atoms are directly bonded to each oxygen atom in a water molecule?

  Two

  
• What are the main roles of water in living organisms?

  Solvent, transport medium, cohesion, freezing, thermal stability, metabolic, habitat
• What makes water a good solvent?

  • It is a polar molecule that can dissolve any polar molecule.
  • It allows metabolic processes to occur by enabling chemicals to react together in solutions.
  • It allows cells to maintain concentration gradients.
• What percentage of cytoplasm is water?

  70-95%
• What are the key properties of liquid water?

  • It is a transport medium for essential materials around organisms and cells.
  • It freezes at 0°C and boils at 100°C.
  • The vast majority of water on Earth is liquid.
• Which tissue in the body is an important transport tissue of oxygen, cholesterol, and hormones?

  Blood
• Approximately what percentage of blood is water?

  Around 80%
• How does cohesion affect the transport of water in plants?

  • Cohesion refers to water molecules sticking to each other, creating surface tension.
  • It helps in the transport of water in the xylem of plants.
  • Some small organisms utilize surface tension to ‘walk’ on water surfaces.
• What are the key characteristics of water when it freezes?

  • Water freezes forming ice.
  • Ice is less dense than water and floats.
  • Floating ice insulates the water beneath, allowing organisms to survive.
• How does water provide thermal stability in large bodies of water?

  • Large bodies of water have fairly constant temperatures due to water's high specific heat capacity.
  • Evaporation removes heat energy, helping regulate temperature.
  • Oceans provide a thermally stable environment.
  • Evaporation serves as a cooling mechanism.
• What are water's metabolic roles in living organisms?

  • Water is a reactant in important chemical processes.
  • It is chemically inert, meaning it doesn't readily participate in unwanted chemical reactions.
  • Used in hydrolysis and photosynthesis.
  • Forms predictable products and doesn't produce unexpected ones.
• What makes water an important habitat?

  • It is a common habitat for many species.
  • Nutrients can be dissolved in water, making them available to organisms.
  • Water contains oxygen essential for life.
  • It supports a wide range of animal species, including fish and marine creatures.
• What type of bond is formed between atoms when they share electrons?

  Covalent bond
• What type of bond forms between polar molecules, and how does it behave?

  Hydrogen bond; it forms, breaks, and re-forms constantly
• What are biological molecules and one important type of bond they can form?

  • Biological molecules are the chemical compounds that make up living organisms.
  • One important type of bond is the hydrogen bond.
• What atoms make up a water molecule?

  2 Hydrogen (H) atoms and 1 Oxygen (O) atom
• What type of bonding holds the atoms in a water molecule together?

  Covalent bonding
• Why do water molecules attract each other?

  • Due to polarisation, where one region of the molecule is more negatively charged than the opposite region.
  • This is caused by the movement of electrons throughout the molecule and electronegativity differences between atoms.
  • Slightly negatively charged regions are momentarily attracted to slightly positively charged regions.
• Which part of a water molecule is more likely to be slightly negatively charged?

  The oxygen part
• Which part of a water molecule is more likely to be slightly positively charged?

  The hydrogen parts
• What should you be able to describe by the end of the video?

  Water molecule structure and properties
• Why is water considered one of the most important molecules in biology?

  Due to its unique properties and roles
• What does a water molecule consist of?

  One oxygen atom and two hydrogen atoms
• What type of bonds exist between the oxygen and hydrogen atoms in water?

  Covalent bonds
• What charge does the oxygen atom in a water molecule have?

  A small negative charge