Chapter 2 Atoms, Molecules, and Life
1) A substance with specific properties that cannot be broken down or converted into another substance is called
2) If you examined the human body, which of the following combinations of elements would be most common?
A) C, O, P, S
B) C, Na, O, N
C) Cl, Ca, C, H
D) C, S, Ca, N
E) O, N, H, C
3) The atomic number of an atom is defined as the:
A) number of electrons in the outermost energy level.
B) total number of energy shells.
C) arrangement of neutrons in the atomic nucleus.
D) number of protons in the atomic nucleus.
E) total number of electrons and neutrons.
4) Phosphorus has an atomic number of 15, so what is the distribution of its electrons?
A) The first energy level has eight and the second has seven.
B) The first energy level has two, the second has eight, and the third has five.
C) The first energy level has two and the second has 13.
D) The first, second, and third energy levels have five electrons each.
E) The electron arrangement cannot be determined from the atomic number alone.
5) Which four elements make up approximately 96% of living matter?
A) carbon, hydrogen, nitrogen, oxygen
B) carbon, sulfur, phosphorus, hydrogen
C) carbon, sodium, chlorine, magnesium
D) carbon, oxygen, sulfur, calcium
E) oxygen, hydrogen, calcium, sodium
6) Imagine that you have been hired as a chemist and your first task is to examine a newly discovered atom. The
paperwork you are given states that its atomic number is 110. What does this mean?
A) The atom contains 110 protons.
B) The atom contains 55 electrons.
C) The atom contains 55 protons and 55 neutrons.
D) The atom is an isotope.
7) Iron is an important element in human body cells. If iron has an atomic number of 26, what does this tell you
about this element?
A) An iron atom has 13 electrons and 13 protons.
B) An iron atom has 13 protons and 13 neutrons.
C) An iron atom has 26 protons.
D) An iron atom is unable to become an isotope.
8) Carbon-14 is often used for carbon dating, where scientists measure the rate of carbon-14 decay to determine the
age of items. Carbon-14 contains six protons and eight neutrons. During the process of carbon-14 decay, one of its