What is the fundamental difference between covalent and ionic bonding?
In a covalent bond, the partners share a pair of electrons; in an ionic bond, one partner accepts electrons from the other.
Which of the following is a trace element in the human body?
Clot formation in our blood can lead to a heart attack or stroke. What was altered in the proteins that made the clot?
The proteins were no longer soluble in the blood.
In the equation 2 H2 + O2 → 2 H2O, the H2 molecules are ________ and the H2O molecules are ________.
reactants . . . products
A solution with a pH of 7 is
An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many electrons does boron have?
Medicines are often administered in pill form. In many cases, the active ingredient of the pill (the drug) is joined to another substance by ________. This forms a(n) ________, which is stable in the dry environment of a pill bottle but dissociates under the wet conditions of the digestive system to release the drug to the body.
ionic bonds . . . salt
Which of the following particles is found in the nucleus of an atom?
protons and neutrons
What is the atomic mass of an atom that has 6 protons, 6 neutrons, and 6 electrons?
The four most common elements in living organisms are
C, H, O, N.
In the equation 2 H2 + O2 → 2 H2O,
only H2O is a compound.
donates H+ ions when conditions become too basic and accepts H+ ions when conditions become too acidic.
Water's surface tension and heat storage capacity is accounted for by its
Which of the following statements best describes a compound?
A compound contains two or more different elements in a fixed ratio.
Which of the following statements about pH is true?
An increase in hydrogen ion concentration means a decrease in pH scale units.
A diabetic, who does not utilize insulin properly, will metabolize fats instead of glucose. A condition called diabetic ketoacidosis is a common result of excessive fat metabolism, causing blood pH values of 7.1 or less (normal range = 7.35 — 7.45). What has happened to the blood pH and why?
The pH is below normal (acidic) because the buffering capacity was exceeded.
Which of the following statements about radioactive isotopes is true?
The energy emitted by radioactive isotopes can break chemical bonds and cause molecular damage in cells.
The tendency of water molecules to stick together is referred to as
A(n) ________ forms when two atoms share electrons.
Which of the following statements regarding matter is false?
Matter can be created and destroyed.
The temperature of evaporation is much higher for water than for alcohol. Without knowing more about the chemistry of alcohol, which of the following is the most logical chemical explanation for this phenomenon?
Fewer hydrogen bonds form between alcohol molecules. As a result, less heat is needed for alcohol molecules to break away from solution and enter the air.
In a water molecule, hydrogen and oxygen are held together by a(n) ________ bond.
Which of the following is dependent on the ability of water molecules to form hydrogen bonds with other molecules besides water?
the universality of water as a solvent
Which of the following best describes the atomic number of an atom?
the number of protons in the atom
Typically, nitrogen atoms are composed of electrons, protons, and neutrons. An isotope of nitrogen could
have more than neutrons.