Hw 2

The structural diversity of carbon-based molecules is determined by which of the following properties?

1. the ability of those bonds to rotate freely 2. the ability of carbon to form four covalent bonds 3. the orientation of those bonds in the form of a tetrahedron

Which one of the following represents the pH of a solution with the HIGHEST concentration of hydrogen ions?

1.0

What percentage of carbon's orbitals are spherical in conformation?

40

14C is an isotope of carbon that possesses:

6 protons, 8 neutrons, and 6 electrons.

If hydrogen bonds between water molecules were, collectively, not as strong as they are, how would this affect plant height?

As hydrogen bonds are responsible for the movement of water through plant vasculature, plants would be shorter.

Because of hydrogen bonding, water is uniquely suited for its central role in life. Many hydrophilic molecules interact freely with water, but a number of hydrophobic molecules are important for life, too. How does the interaction between water and hydrophobic molecules help to organize biological systems?

Because water molecules preferentially associate with each other, they force hydrophobic molecules to associate with each other and not with water molecules.

Evidence exists that atmospheric CO2 has increased over the last several decades due to human activities. How does increased CO2 levels affect the pH of Earth's waters?

Due to the formation of carbonic acid, increased CO2 levels decrease the pH of Earth's waters.

Which of the following statements about water is correct? Water molecules in ice demonstrate a disorganized, non-lattice arrangement. Ice is more dense than liquid water. Ice is less dense than liquid water. Ice forms on top and sinks to the bottom of lakes and rivers. Bodies of water freeze from the bottom up.

Ice is less dense than liquid water.

Recall that a carbon atom behaves as if it possesses four valence electrons. Given this information, what is the MOST likely structural formula for carbon dioxide (CO2)?

O=C=O

A woman's doctor tells her to gargle with salt water. She stirs a tablespoon of salt into a cup of warm water and watches it dissolve. Why does the salt dissolve in water?

The positive hydrogen atoms in water molecules are attracted to chlorine ions, and the negative oxygen atoms in water molecules are attracted to sodium ions.

A woman's doctor tells her to gargle with salt water. She stirs a tablespoon of salt into a cup of warm water, and watches it dissolve. Why does the salt dissolve in water?

The positive hydrogen atoms in water molecules are attracted to chlorine ions, and the negative oxygen atoms in water molecules are attracted to sodium ions.

Which statement BEST describes an effect of the low density of frozen water in a lake?

When water in a lake freezes, it floats, providing insulation for organisms below the ice.

Of the following types of bonds between atoms, which is the STRONGEST?

covalent bond

A pair of shared valence electrons is referred to as a(n):

covalent bond.

Hydrogen bonding is ultimately due to differences in _____ between two atoms.

electronegativity

The ability of atoms to attract electrons is referred to as:

electronegativity.

As water is heated, the temperature rises before any hydrogen bonds between water molecules are broken.

false

Water is neither hydrophilic nor hydrophobic, as these terms only define the interaction of other molecules with water molecules.

false

A pair of atoms joined by a polar covalent bond:

has a slight positive charge on one atom and a slight negative charge on the other.

A young girl is staring at the raindrops running down her window. She notices that the raindrops remain more or less intact, even as they cascade down the windowpane. This is a result of:

hydrogen bonds between water molecules.

Water readily dissolves compounds that are referred to as:

hydrophilic

Which of the following bonds rely on the attraction of positive and negative charges?

ionic bonds and hydrogen bonds

Which of the following statements regarding an atom with high electronegativity is true? 1. It will have fewer protons than an atom with low electronegativity. 2. It will have a tendency not to attract electrons. 3. It will most likely be located on the left-most side of the periodic table of elements. None of the other answer options is correct.

none

Some species of insects are able to walk across liquid water because:

of the high surface tension of water due to its cohesion.

Which one of the following elements is likely to form exactly three non-ionic interactions with hydrogen?

phosphorus

A water molecule contains what type of bond?

polar covalent

The unique properties of water are due to the _____ of water molecules and the ability of water to form _____ with other water molecules and with other polar molecules.

polarity; hydrogen bonds

Which of the following CORRECTLY pairs the particles of an atom with their physical properties?

proton-positively charged; neutron-uncharged; electron-negatively charged

Which of the following is an example of a hydrogen bond?

the bond that forms between hydrogen and oxygen atoms within different water molecules

Which of the following accurately describes a polar covalent bond?

the unequal sharing of electrons between an atom with a partial positive charge, and an atom with a partial negative charge

Part of the reason why salt dissolves in water is that hydrogen bonds form between water molecules and chlorine ions.

true