Chapter 2

six

A carbon atom has an atomic number of 6 and an atomic mass of 12. Assuming it is neither an ion nor part of a molecule, how many electrons does it have?

6 valence electrons, 2 open binding sites

A chemist seeks an element with only two open binding sites in the valence shell. He consults the periodic table and finds that oxygen has an atomic number of 8. How many electrons does oxygen have in its valence shell? How many open binding sites?

4

Carbon has an atomic number of 6. This means it has 6 protons and 6 electrons. How many valence electrons does carbon have?

Functional groups confer special chemical properties to molecules.

Functional groups are very important in organic chemistry. Why are they considered to play such a critical role?

No, hydrocarbons are organic molecules consisting entirely of carbon and hydrogen.

Glucose has a chemical formula of C6H12O6. Would glucose be considered a hydrocarbon?

Noble gases do not form covalent bonds with other atoms.

How many covalent bonds do noble gases form in nature?

A base provides either hydroxide ions (OH-) or negatively charged ions that combine with hydrogen ions (H+).

In chemistry, what is a base?

1 x 10

The pH scale is based on the hydrogen ion (H+) concentration of pure water, which has a pH of 7. What is the net difference in hydrogen ion (H+) concentration between pH 7 and pH 8?

covalent

bonds between hydrogen and oxygen within a water molecule are quite strong. What do we call these types of bonds?

The period of time required for 50 percent of an element to decay into another element

what is the half-life of an element?

Hydrogen

which type of chemical bond is responsible for zipping together the two strands of a DNA molecule?

Hydrogen

Water has many unique properties due to the bonds between the water molecules. Which type of bond is found between individual water molecules?

Water can only dissolve polar molecules and ionic compounds. Oils (lipids) are nonpolar.

We refer to water as a solvent. Why do oil and water not mix then?

In ionic bonds, one or more electrons are transferred between atoms, whereas atoms in covalent bonds share electrons.

What is the major difference between ionic and covalent bonds?

charge

When an atom becomes an ion, which property changes the most?

The carbon atom's ability to form four covalent bonds to as many as four different atoms makes it a fundamental structural component in the organic macromolecules.

When exploring the Universe, looking for life, most scientists agree we should look for "carbon-based life forms." Why is carbon considered so important to life?

Elements within the same group share the same electron configuration in their valence shells.

Which of the following describes the property shared by elements within the same column (or group) in the periodic table of elements?

Ethane

Which of the following is a two-carbon hydrocarbon with a single-carbon carbon bond?

An isotope

While analyzing data from the prior week, a chemist determines that she has discovered a new type of atom. While the atom has the same number of protons as nitrogen, the number of neutrons is different. What has she discovered?

Relative differences in electronegativity between elements in a molecule result in negatively charged electrons spending more time near some elements than others, resulting in asymmetrical charge distributions.

Why are some molecules electrically neutral, whereas others display polarity?