Bio Chapter 2

The atomic number of each atom is given to the left of each of the elements below. Which of the atoms has the same valence as carbon (126C)? A) 10Ne neon B) 12Mg magnesium C) 14Si silicon D) 9F flourine E) 7N nitrogen

14Si silicon

From its atomic number of 15, it is possible to predict that the phosphorus atom has A) 15 neutrons. B) 15 electrons. C) 15 protons. D) 8 electrons in its outermost electron shell. E) 15 protons and 15 electrons.

15 protons and 15 electrons

An atom has 6 electrons in its outer shell. How many unpaired electrons does it have? A) 2 or 4 B) 2 C) 6 D) 0 E) 4

2

What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen? A) 2 B) 6 C) 3 D) 4 E) 1

2

Oxygen has an atomic number of 8 and a mass number of 16. Thus, what is the atomic mass of an oxygen atom? A) approximately 16 grams B) approximately 24 grams C) approximately 8 grams D) approximately 8 daltons E) approximately 16 daltons

approximately 16 daltons

Knowing just the atomic mass of an element allows inferences about which of the following? A) the number of protons plus electrons in the element B) the number of neutrons in the element C) the number of electrons in the element D) the number of protons plus neutrons in the element E) the number of protons in the element

the number of protons plus neutrons in the element

One difference between carbon-12 (126C) is that carbon-14 (146C) has A) two more protons than carbon-12. B) two more electrons and two more neutrons than carbon-12. C) two more neutrons than carbon-12. D) two more protons and two more neutrons than carbon-12. E) two more electrons than carbon-12.

two more neutrons than carbon-12

If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which of the molecules below would be formed? A) H-S-H ! H B) H=S=H C) H-S-H D) S-H H ! E) H-S-H ! H

H-S-H

The atomic number of nitrogen is 7. Nitrogen-15 is heavier than nitrogen-14 because the atomic nucleus of nitrogen-15 contains how many neutrons? A) 7 B) 8 C) 12 D) 6 E) 14

8

Which of the following statements is false? A) All organisms require the same elements in the same quantities. B) Iron is an example of an element needed by all organisms. C) Some naturally occurring elements are toxic to organisms. D) Carbon, hydrogen, oxygen, and nitrogen are the most abundant elements of living matter. E) Approximately one-quarter of the natural elements are essential elements.

All organisms require the same elements in the same quantities

What does the term electron orbital describe? A) An electron orbital describes the orbit of an electron around the nucleus. B) An electron orbital describes the exact distance of an electron from the nucleus. C) An electron orbital describes a three-dimensional space where an electron can be found 90% of the time.

An electron orbital describes a three-dimensional space where an electron can be found 90% of the time

The atomic number of neon is 10. Therefore, which of the following is most correct about an atom of neon? A) It has 8 electrons in its outer electron shell. B) It has 8 electrons in its outer electron shell and it is inert. C) It has an atomic mass of 10 daltons. D) It has 8 electrons in its outer electron shell, it is inert, and it has an atomic mass of 10 daltons. E) It is inert.

It has 8 electrons in its outer electron shell and it is inert

An atom with atomic number 12 would have what type of chemical behavior in bonding with other elements? A) It would form two covalent bonds with other atoms. B) It would form ions with a +1 charge. C) It would form ions with a -2 charge. D) It would form ions with a +2 charge. E) It would form ions with a -1 charge.

It would form ions with a +2 charge

Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers of 92, 94, 95, 96, 97, 98, and 100. Therefore, which of the following can be true? A) The isotopes of molybdenum can have between 50 and 58 protons. B) Molybdenum atoms can have between 50 and 58 neutrons. C) The isotopes of molybdenum have between 50 and 58 protons and have different electron configurations. D) The isotopes of molybdenum have between 50 and 58 neutrons and have different electron configurations. E) The isotopes of molybdenum have different electron configurations.

Molybdenum atoms can have between 50 and 58 neutrons

The nucleus of a nitrogen atom contains 7 neutrons and 7 protons. Which of the following is a correct statement concerning nitrogen? A) The nitrogen atom has a mass number of approximately 14 and an atomic number of 7. B) The nitrogen atom has a mass number of approximately 14 and an atomic number of 14. C) The nitrogen atom has a mass number of approximately 7 and an atomic number of 21. D) The nitrogen atom has a mass number of approximately 14 and an atomic number of 21 E) The nitrogen atom has a mass number of approximately 7 and an atomic number of 14.

The nitrogen atom has a mass number of approximately 14 and an atomic number of 7

About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter? A) oxygen, hydrogen, calcium, nitrogen B) carbon, sodium, hydrogen, nitrogen C) carbon, hydrogen, nitrogen, oxygen D) carbon, oxygen, phosphorus, hydrogen E) carbon, oxygen, nitrogen, calcium

carbon, hydrogen, nitrogen, oxygen

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants? A) sodium B) nitrogen C) iodine D) phosphorus E) calcium

iodine

Phosphorus-32, a radioactive isotope of phosphorus-31 (atomic number 15), undergoes a form of radioactive decay whereby a neutron turns into a proton, which is retained in the nucleus, and emits radiation in the form of an electron. What is the product of such radioactive decay of phosphorus-32? A) a negatively charged phosphorus-32 ion B) sulfur-32 (atomic number 16) C) a positively charged phosphorus-31 ion D) phosphorus-31 E) the conversion of the phosphorus-32 atom into pure energy

sulfur-32 (atomic number 16)