Question

module 2
9 what do all isotopes of an element have in common? what differs?
10 what design attribute of water allows for so many unusual, life - supporting properties?
11 explain what makes a water molecule polar.
12 match the property of water with its description.
description
a. water’s ability to attract other water molecules
b. water’s ability to absorb large amounts of thermal energy before its temperature increases
c. water’s ability to float as a solid
d. water’s ability to attract other polar substances
e. water’s ability to dissolve substances
answer
property
a. universal solvent
b. adhesion
c. high heat capacity
d. cohesion
e. density

Explanation:

Question 9

Isotopes of an element have the same number of protons (atomic number) as the element, which defines the element's identity. They differ in the number of neutrons, leading to different atomic masses.

Water is a polar molecule with a bent structure (due to two lone pairs on oxygen). The electronegativity difference between oxygen and hydrogen creates partial charges, allowing hydrogen bonding. This polarity and hydrogen bonding give water properties like cohesion, adhesion, high heat capacity, and being a universal solvent.

A water molecule ($H_2O$) has an oxygen atom bonded to two hydrogen atoms. Oxygen is more electronegative than hydrogen, so it pulls the shared electrons in the covalent bonds closer to itself. This creates a partial negative charge ($\delta^-$) on the oxygen and partial positive charges ($\delta^+$) on the hydrogens. The molecule is also bent (due to lone pairs on O), so the polar bonds don't cancel out, resulting in a net dipole moment.

Answer:

Common: Same number of protons (atomic number). Differs: Number of neutrons (atomic mass).

Question 10