Chapter 2: Chemical Components of Cells

Question 1

Define the following terms

Atom:

Element:

Molecule:

Covalent Bond:

Ionic Bond:

Atomic Number:

Atomic Mass:

Subatomic Particles:

Answer 1

Atom:The smallest particle of an element that still retains its distinctive chemical properties; consists of a positively charged nucleus surrounded by a cloud of negatively charged electrons.

Element: A substance that cannot be decomposed into simpler substances by chemical means, and is made up of atoms all with an identical number of protons.

Molecule: Group of atoms joined together by covalent bonds.

Covalent Bond: Stable chemical link between two atoms produced by sharing one or more pairs of electrons.

Ionic Bond: Interaction formed when one atom donates electrons to another; this transfer of electrons causes both atoms to become electrically charged.

Atomic Number: The number of protons in the nucleus of an atom

Atomic Mass: It is approximately equivalent to the number of protons and neutrons in the atomor to the average number allowing for the relative abundances of different isotopes.

Subatomic Particles: Any of various particles of matter that are smaller than a hydrogen atom. Protons, neutrons, and electrons are subatomic particles by definitive means.

Question 2

Draw a Carbon atom with the correct number of protons and electrons (in the electron shells).

Answer 2

Question 3

What are the three main types of chemical bond? How are the bonds different from each other?

Answer 3

Ionic bonds: Electrons are transferred between atoms. An ion will give one or more electrons to another ion. Table salt, sodium chloride (NaCl), is a common example of an ionic compound.

Hydrogen bond: is an intermolecular attractive force in which a hydrogen atom that is covalently bonded to a small, highly electronegative atom is attracted to a lone pair of electrons on an atom in a neighboring molecule. Hydrogen bonds are very strong compared to other dipole interactions. The strength of a typical hydrogen bond is about 5% of that of a covalent bond.

Covalent Bond: is the force of attraction that holds together two nonmetal atoms that share a pair of electrons. One electron is provided by each atom, and the pair of electrons is attracted to the positive nuclei of both atoms.

Question 4

Draw a water molecule. What type of bond holds together a water molecule?

Answer 4

Hydrogen bonds are what holds together a water molecule. attracted towards the oxygen atom of a neighboring water molecule; generally, a proton shared by two lone electron pair

Question 5

Why is water polar? What type of bond results from water’s polarity (when there is more than one water molecule)?

Answer 5

is polar because of the bent shape of the molecule. The shape means most of the negative charge from the oxygen on side of the molecule and the positive charge of the hydrogen atoms is on the other side of the molecule.

Question 6

What does it mean to be hydrophilic? Why does salt dissolve easily in water? Why does sugar dissolve easily in water?

Answer 6

Molecule or part of a molecule that readily forms hydrogen bonds with water, allowing it to readily dissolve; literally, “water loving.” individual molecules are held together by relatively weak intermolecular forces. When sugar dissolves in water, the weak bonds between the individual sucrose molecules are broken much like as salts dissociate into their ions when they dissolve in water.

Question 7

Draw each functional group. :

Hydroxyl =

Carbonyl =

Carboxyl =

Phosphate =

Amino =

Sulfhydryl =

Answer 7