Free Printable Properties of Water Worksheet Collection - Free Printable

Amoeba Sisters Video Select Recap: Properties of Water

#### 1. The molecule of water is described as a polar molecule. Polar molecules have an unequal sharing of electrons. Explain how this unequal sharing is present by using our water molecule graphic below.

Explanation:
- In a water molecule (H₂O), the oxygen atom is more electronegative than the hydrogen atoms. This means that the oxygen atom attracts the shared electrons more strongly.
- As a result, the electrons spend more time around the oxygen atom, giving it a partial negative charge (δ⁻).
- The hydrogen atoms, having less electron density, acquire a partial positive charge (δ⁺).
- This unequal sharing of electrons creates a dipole in the water molecule, making it polar.

Answer:
The oxygen atom in a water molecule is more electronegative than the hydrogen atoms, causing the shared electrons to be pulled closer to the oxygen. This results in the oxygen having a partial negative charge (δ⁻) and the hydrogen atoms having partial positive charges (δ⁺), making the water molecule polar.

---

#### 2. Water is an excellent solvent. With water being a polar molecule, it can be an especially strong solvent for other polar molecules. Give an example of how water acting as a solvent is important for living organisms.

Explanation:
- Water's polarity allows it to dissolve many substances, particularly ionic compounds and polar molecules. This property is crucial for biological processes.
- For example, water dissolves salts (like sodium chloride, NaCl) into ions (Na⁺ and Cl⁻), which are essential for maintaining cellular functions such as osmotic balance and nerve impulse transmission.
- Water also dissolves nutrients like glucose and amino acids, allowing them to be transported throughout the body.

Answer:
Water acts as a solvent to dissolve essential substances like salts (e.g., NaCl) and nutrients (e.g., glucose). This is critical for living organisms because it enables the transport and utilization of these substances within cells and throughout the body, supporting vital processes like nerve signaling and energy metabolism.

---

#### 3. The below picture shows water’s ability for adhesion and cohesion. Define adhesion and cohesion and explain why they are important for the plant in the graphic below.

Explanation:
- Cohesion: The attraction between water molecules due to hydrogen bonding. This property allows water molecules to "stick" to each other.
- Adhesion: The attraction between water molecules and other surfaces (e.g., the walls of xylem vessels in plants). This property allows water to adhere to surfaces.

In the context of the plant:
- Cohesion helps water move upward through the xylem vessels against gravity. The continuous chain of water molecules stays intact due to hydrogen bonding.
- Adhesion allows water to stick to the walls of the xylem vessels, further aiding its upward movement.

Answer:
- Cohesion: The attraction between water molecules, allowing them to stick together due to hydrogen bonding.
- Adhesion: The attraction between water molecules and other surfaces (e.g., xylem vessel walls).
- These properties are important for plants because they enable water to move upward from the roots to the leaves through the xylem, ensuring that all parts of the plant receive the water and dissolved nutrients needed for survival.

---

#### 4. Describe the property of water being shown below. How do water’s hydrogen bonds contribute to this property?

Explanation:
- The image shows water forming a droplet on a surface, demonstrating the property of surface tension.
- Surface tension occurs because water molecules at the surface are pulled inward by the cohesive forces of other water molecules beneath them. This creates a "skin-like" effect on the surface of the water.
- Hydrogen bonds play a key role in this property. The strong hydrogen bonds between water molecules create a tight network at the surface, resisting external forces and allowing objects (like insects) to "walk" on water.

Answer:
The property shown is surface tension. Water’s hydrogen bonds contribute to surface tension by creating strong cohesive forces between water molecules at the surface, pulling them inward and resisting external forces. This allows water to form droplets and supports phenomena like insects walking on water.

---

Final Answers:

1. The oxygen atom in a water molecule is more electronegative than the hydrogen atoms, causing the shared electrons to be pulled closer to the oxygen. This results in the oxygen having a partial negative charge (δ⁻) and the hydrogen atoms having partial positive charges (δ⁺), making the water molecule polar.
2. Water acts as a solvent to dissolve essential substances like salts (e.g., NaCl) and nutrients (e.g., glucose). This is critical for living organisms because it enables the transport and utilization of these substances within cells and throughout the body, supporting vital processes like nerve signaling and energy metabolism.
3. Cohesion: The attraction between water molecules, allowing them to stick together due to hydrogen bonding.
Adhesion: The attraction between water molecules and other surfaces (e.g., xylem vessel walls).
These properties are important for plants because they enable water to move upward from the roots to the leaves through the xylem, ensuring that all parts of the plant receive the water and dissolved nutrients needed for survival.
4. The property shown is surface tension. Water’s hydrogen bonds contribute to surface tension by creating strong cohesive forces between water molecules at the surface, pulling them inward and resisting external forces. This allows water to form droplets and supports phenomena like insects walking on water.

Final Answer Box:
\boxed{
1. Oxygen is more electronegative, causing partial charges.
2. Dissolves salts and nutrients for transport.
3. Cohesion: Molecules stick together; Adhesion: Sticks to surfaces; Important for water transport in plants.
4. Surface tension; Hydrogen bonds create cohesive forces at the surface.
}