Structure of Water and Hydrogen Bonding

The property of water that allows water molecules to stick to each other is

• adhesion

• cohesion

• density

• specific heat

Tags

NGSS.HS-ESS2-5

Small insects can walk across the surface of calm water. Their feet push the surface of the water down slightly, somewhat like a person walking across a trampoline, but they do not break the surface. What is the best explanation for why this happens?

• The insects are light enough so that they do not break the hydrogen bonds holding the water molecules together

• The insects actually use their wings to hover slightly above the water's surface and they only skim it with their feet

• The insects' feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water's surface

• The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next

The partial negative charge at one end of a water molecule is attracted to a partial positive charge of another water molecule. What is this type of attraction called?

• a polar covalent bond

• an ionic bond

• a hydration shell

• a hydrogen bond

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

• hydrogen bonds.

• nonpolar covalent bonds

• polar covalent bonds.

• ionic bonds.

• van der Waals interactions

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?

• a covalent bond

• a hydrogen bond

• an ionic bond

• a hydrophilic bond

• a hydrophobic bond

An example of a hydrogen bond is the bond between

• C and H in methane (CH4).

• the H of one water molecule and the O of another water molecule.

• Na+and Cl- in salt.

• the two hydrogen atoms in a molecule of hydrogen gas (H2).

• Mg+and Cl- in MgCl2.

Water is able to form hydrogen bonds because

• oxygen has a valence of 2.

• the water molecule is shaped like a tetrahedron.

• the bonds that hold together the atoms in a water molecule are polar covalent bonds.

• the oxygen atom in a water molecule has a weak positive charge.

• each of the hydrogen atoms in a water molecule is weakly negative in charge.

What gives rise to the cohesiveness of water molecules?

• hydrophobic interactions

• nonpolar covalent bonds

• ionic bonds

• hydrogen bonds

• both A and C

The bonds that are broken when water vaporizes are

• ionic bonds.

• hydrogen bonds between water molecules.

• covalent bonds between atoms within water molecules.

• polar covalent bonds.

• nonpolar covalent bonds

Why does ice float in liquid water?

• The liquid water molecules have more kinetic energy and thus support the ice.

• The ionic bonds between the molecules in ice prevent the ice from sinking.

• Ice always has air bubbles that keep it afloat.

• Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water

• The crystalline lattice of ice causes it to be denser than liquid water