1. ATOMIC CONCEPTS
Regents Review

2. Regents Review 1. A neutron has approximately the same mass as a
A)    An alpha particle
B)    A beta particle
C)    An electron
D)    A proton
Correct Answer: Option D - A proton

3. Regents Review 2. Which atom contains exactly 15 protons? A) P-32
B)    S-32
C)    O-15
D)    N-15
Correct Answer: Option A - P-32
The 32 is the weight of that isotope. The number of protons is always the atomic number (An atom with 15 protons also has an atomic number of 15) So if you take the isotope number (32) and subtract the proton number (15) you get the number of neutrons for that isotope. (17).

4. Regents Review
3. When electrons in an atom in an excited state fall to lower energy levels, energy is
A)    Absorbed, only
B)    Released, only
C)    Neither released nor absorbed
D)    Both released and absorbed
Correct Answer: Option B - Released, only
The ground state is the lowest energy state. To raise the atom to an excited state, energy must be added. To fall back to the ground state (lowest energy), the energy it had absorbed must be released in the form of light or radiation.

5. Regents Review
4. What is the mass number of an atom which contains 28 protons, 28 electrons, and 34 neutrons?
A)    28
B)    62
C)    56
D)    90
Correct Answer: Option - B - 62
The atomic number is equal to the number of protons in an atom's nucleus. The atomic number is the number of protons in an atom of an element. By definition, atoms have no overall electrical charge. That means that there must be a balance between the positively charged protons and the negatively charged electrons. Atoms must have equal numbers of protons and electrons. Atomic mass is found by adding protons plus neutrons = 62. Electrons have a mass of nearly 0 so they are not counted in the formula for atomic mass.

6. Regents Review
5. Atoms of the same element that have different numbers of neutrons are classified as:
A)    Isotopes
B)    Charged atoms
C)    Isomers
D)    Charged nuclei
Correct Answer: Option A - Isotopes
Atoms of the same element can have different numbers of neutrons; the different possible versions of each element are called isotopes. For example, the most common isotope of hydrogen has no neutrons at all; there's also a hydrogen isotope called deuterium, with one neutron, and another, tritium, with two neutrons.

7. Regents Review 6. Which symbols represent atoms that are isotopes?
A)    C-14 and N-14
B)    O-16 and O-18
C)    Rn-222 and Ra-222
D)    I-131 and I-131
Correct Answer: Option D - I-131 and I-131
Isotopes are atoms of the same element with same atomic number but, with a different number of neutrons (different atomic mass). Hence, only option D is correct.

8. Regents Review
7. Compared to the charge and mass of a proton, an electron has
A)    The same charge and a smaller mass
B)    The same charge and the same mass
C)    An opposite charge and a smaller mass
D)    An opposite charge and the same mass
Correct Answer: Option C - An opposite charge and a smaller mass
Protons are positively charged and electrons are negatively charged. An electron has a mass that is approximately 1843 times less than that of the proton. The proton is a subatomic particle with an electric charge of +1 elementary charge.

9. Regents Review
8. Compared to an electron in the first electron shell of an atom, an electron in the third shell of the same atom has:
A)    Less mass
B)    More mass
C)    Less energy
D)    More energy
Correct Answer: Option D - More energy
Electron shells in an atom are orbits in which electrons move around the nucleus. The closer orbit more tightly bound are the electrons and lesser is the energy they posses for reactions. As the electrons move farther from the nucleus they are less bound to the nucleus and have higher energy available for reaction.

10. Regents Review
9. What is the atomic number, of an ion with 5 protons, 6 neutrons, and a charge of 3+?
A)    5
B)    6
C)    8
D)    11
Correct Answer: Option A - 5
The number of protons in the nucleus of an atom is known as the atomic number, which determines the chemical element to which the atom belongs. The chemical properties of each atom are determined by the number of (negatively charged) electrons, which for neutral atoms is equal to the number of (positive) protons so that the total charge is zero. There are 5 protons so the atomic number is also 5. The charge of an atom is not involved in arriving at the atomic number of that atom.

11. Regents Review
10. In which group do the particles contain only nucleons?
A)    Protons and electrons
B)    Neutrons and electrons
C)    Protons and neutrons
D)    Protons, neutrons, and electrons
Correct Answer: Option C - Protons and neutrons

12. Regents Review
11. What is the electron configuration of a sulfur atom in the ground state?
A)    2-4
B)    2-8-4
C)    2-6
D)    2-8-6
Correct Answer: Option D

13. Regents Review
12. Which element's ionic radius is smaller than its atomic radius?
A)    Neon
B)    Sodium
C)    Nitrogen
D)    Sulfur
Correct Answer: Option B - Sodium
Elements that lose electrons form positive ions that are smaller than atoms of the same element. Therefore the ionic radius of these ions is smaller than its atomic radius. Only option B, sodium, is a metal that will lose electrons.

14. Regents Review
13. What is the total number of neutrons in an atom of  5726Fe?
A)    26
B)    57
C)    31
D)    83
Correct Answer: Option C - 31
The atomic mass being 56 is the sum of the protons and neutrons of the nucleus = 57
The atomic number (number of protons) in the nucleus = 26
Number of neutrons = Atomic mass - Atomic number = = 31

15. Regents Review
14. In which shell are the valence electrons of the elements in Period 2 found?
A)    1
B)    2
C)    3
D)    4
Correct Answer: Option B - 2
Valence electrons are the electrons contained in the outermost, or valence, electron shell of an atom. Valence electrons are important in determining how an element reacts chemically with other elements: The fewer valence electrons an atom holds the less stable it becomes and the more likely it is to react. The reverse is also true, the more full/complete the valence shell is with valence electrons, the more inert an atom is and the less likely it is to chemically react with other chemical elements or with chemical elements of its own type.

16. Regents Review
15. How many electrons are in the outermost principal energy level of an atom of carbon in the ground state?
A)    6
B)    2
C)    3
D)    4
Correct Answer: Option D - 4
The electronic configuration of carbon in the ground state is:

17. Regents Review
16. When alpha particles are used to bombard gold foil, most of the alpha particles pass through undeflected. This result indicates that most of the volume of a gold atom consists of:
A)    Deuterons
B)    Neutrons
C)    Protons
D)    Unoccupied space
Correct Answer: Option D - Unoccupied space
Because most of the particles do not hit anything (pass right through), one can infer the atom is mostly empty space.

18. Regents Review
17. The elements in Period 3 all contain the same number of
A)    Occupied principal energy levels
B)    Protons
C)    Neutrons
D)    Valence electrons
Correct Answer: Option A - Occupied principal energy levels

19. Regents Review
18. Which statement about the mass of an electron is correct?
A)    The mass of an electron is equal to the mass of a proton.
B)    The mass of an electron is less than the mass of a proton.
C)    The mass of an electron is equal to the mass of a neutron.
D)    The mass of an electron is greater than the mass of a neutron.
Correct Answer: Option B - The mass of an electron is less than the mass of a proton.

20. Regents Review
19. What is the atomic number of an element that has six protons and eight neutrons?
A)    8
B)    10
C)    6
D)    14
Correct Answer: Option C - 6
The atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element. In an atom of neutral charge, atomic number is equal to the number of electrons.

21. Regents Review 21. An atom is electrically neutral because
A)    Number of protons equals the number of electrons
B)    Number of protons equals the number of neutrons
C)    Ratio of the number of neutrons to the number of electrons is 1:1
D)    Ratio of the number of neutrons to the number of protons is 2:1
Correct Answer: Option A - Number of protons equals the number of electrons

22. Regents Review
22. Atoms of which element have the greatest tendency to gain electrons?
A)    Bromine
B)    Fluorine
C)    Chlorine
D)    Iodine
Correct Answer: Option B - Fluorine

23. Regents Review
23. Which element is a good conductor of electricity and a solid at standard temperature and pressure?
A)    Nickel
B)    Iodine
C)    Mercury
D)    Sulfur
Correct Answer: Option A - Nickel
Nickel is silvery-white, malleable and ductile metal. It is one of the elements of the iron group and it takes on a high polish. It is a solid and a fairly good conductor of heat and electricity at STP; due to its characteristic of being bivalent.

24. Regents Review
24. How do the energy and the most probable location of an electron in the third shell of an atom compare to the energy and the most probable location of an electron in the first shell of the same atom?
A)    In the third shell, an electron has more energy and is closer to the nucleus.
B)    In the third shell, an electron has less energy and is closer to the nucleus.
C)    In the third shell, an electron has less energy and is farther from the nucleus.
D)    In the third shell, an electron has more energy and is farther from the nucleus.
Correct Answer: Option D - In the third shell, an electron has more energy and is farther from the nucleus.

25. Regents Review
25. A sample composed only of atoms having the same atomic number is classified as
A)    A compound
B)    An element
C)    A solution
D)    An isomer
Correct Answer: Option B - An element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.

26. Regents Review
26. What does the wave-mechanical model of the atom state?
A)    Atoms travel in defined circles
B)    Atoms are most likely found in an excited state
C)    Atoms have a positive charge
D)    Atoms are located in orbitals outside the nucleus
Correct Answer: Option D - Atoms are located in orbitals outside the nucleus

27. Regents Review
27. Which two particles each have a mass approximately equal to one atomic mass unit?
A)    Electron and neutron
B)    Electron and positron
C)    Proton and neutron
D)    Proton and electron
Correct Answer: Option C - Proton and neutron

28. Regents Review 28. Which phrase describes an atom?
A)    A negatively charged electron cloud surrounding a positively charged nucleus
B)    A positively charged electron cloud surrounding a positively charged nucleus
C)    A positively charged electron cloud surrounding a negatively charged nucleus
D)    A negatively charged electron cloud surrounding a negatively charged nucleus
Correct Answer: Option A - A negatively charged electron cloud surrounding a positively charged nucleus

29. Regents Review
29. Among the following combinations, which total mass is the smallest?
A)    The sum of the masses of 1 electron and 1 proton
B)    Mass of 2 electrons
C)    Mass of 2 neutrons
D)    The sum of the masses of 1 neutron and 1 electron
Correct Answer: Option B - Mass of 2 electrons

30. Regents Review
30. Elements on the modern Periodic Table are arranged in order of increasing
A)    Atomic mass
B)    Number of neutrons
C)    Number of valence electrons
D)    Atomic number
Correct Answer: Option D - Atomic number
The atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element. In an atom of neutral charge, atomic number is equal to the number of electrons.