June 2023
11 Which changes in both charge and radius occur when an atom loses an electron?
(1) A negative ion is formed with a smaller radius than the atom.
(2) A negative ion is formed with a larger radius than the atom.
(3) A positive ion is formed with a smaller radius than the atom.
(4) A positive ion is formed with a larger radius than the atom.
Solution: An electron has a -1 charge. When an electron is lost, a positive ion will be formed (since there will be more protons (+1 charge) than electrons). Losing an electron will also decrease the radius of an atom.
Answer: 3
35 Compared to the metals in Period 2, the nonmetals in Period 2 have
(1) lower first ionization energies and lower electronegativity values
(2) lower first ionization energies and higher electronegativity values
(3) higher first ionization energies and lower electronegativity values
(4) higher first ionization energies and higher electronegativity values
Solution: Ionization energy and electronegativity increase as we go from the left to the right across a Period on the Periodic Table. Metals are to the left of the staircase on the Periodic Table and nonmetals are to the right. If you do not remember the trend for ionization energy and electronegativity, you can also compare the value of elements in Table S on the Reference Table.
Answer: 4
34 At room temperature, a student determines the density of a sample of nickel to be 9.79 g/cm3. Based on Table S, what is the student’s percent error for the density of nickel?
(1) 0.091%
(2) 0.10% (3) 9.1%
(4) 10.%
Solution: According to table S, the density of nickel is 8.90 g/cm3. Table T shows the formula for % error which is
% error= (measured value – accepted value/accepted value)*100.
Now all we need to do is plug everything in. The values in Table S are accepted values.
Answer: 4
January 2023
4 Which list of elements includes a metal, a metalloid, and a noble gas?
(1) Rb, Cl, Ne
(2) Sr, Si, Rn
(3) Rn, Cl, Ne
(4) Si, Rb, Sr
Solution: Metals are to the left of the staircase on the Periodic Table. Nobles gases are group 18 on the Periodic Table. Metalloids are on the staircase on the Periodic Table and include: B, Si, Ge, As, Sb, Te.
Answer: Choice 2 is correct.
5 Which element has the lowest density at 298 K and 101.3 kPa?
(1) argon
(2) fluorine
(3) nitrogen
(4) oxygen
Solution: Table S on the Reference Table lists all of the densities for all the elements on the Periodic Table.
Answer: Choice 3 is correct
7 Which element has chemical properties most similar to sulfur?
(1) argon
(2) fluorine
(3) nitrogen
(4) oxygen
Solution: Elements in the same group (column) on the Periodic Table have similar chemical properties due to the same number of valence electrons.
Answer: Choice 4 is the correct answer.
August 2022
6. Which Group 15 element is classified as a metal?
(1) N
(2) P
(3) As
(4) Bi
Solution: Refer to the Periodic Table on the reference table. Groups are vertical columns. Group 15 has the following elements: N, P, As, Sb, and Bi. Notice the periodic table has a staircase diving it into two sections. To the right of the staircase are nonmetals. To the left of the staircase are metals. Metalloids(B, Si, Ge, As, Sb, Te, At) are located on the staircase. Nitrogen is to the right of the staircase and is therefore nonmetal. Same goes for phosphorus. As is on the staircase and is a metalloid. Bi is to the left of the staircase and is a metal!
Answer: 4
7. Compared to the number of electron shells and radius of an aluminum atom in the ground state, a boron atom in the ground state has
(1) fewer electron shells and a smaller radius
(2) fewer electron shells and a larger radius
(3) more electron shells and a smaller radius
(4) more electron shells and a larger radius
Solution: Let's first find Aluminum and Boron on the Periodic Table on our reference table. Aluminum (Al) is number 13 and boron (B) is number 5.
Aluminum is in the third period (row) and has 3 electron shells while boron is in the second period and has 2 electron shells. Therefore, boron has fewer electron shells. Less electron shells means smaller radius.
Atomic radius increases up and to the right. Alternatively, you can actually look up atomic radius in Table S for each element and compare the two element given.
Answer: 1
June 2022
4 The elements on the Periodic Table of the Elements are arranged in order of increasing
(1) atomic mass
(2) atomic number
(3) mass number
(4) oxidation state
Solution: This answer is just another fact that needs to be memorized for the chemistry regents exam. Elements on the Periodic Table are arranged in in order of increasing atomic number.
Answer: 2
5 Atoms of which element in Group 15 have the greatest electronegativity?
(1) As
(2) Bi
(3) N
(4) P
Solution: There are two ways to do this question. First, is to remember that electronegativity increases up and to the right on the Periodic Table. Another way is to simply check Table S on the Reference Table. It lists the electronegativity values for all the elements.
Answer: 3
9 Krypton atoms in the ground state tend not to bond with other atoms because their
(1) second electron shell contains eight electrons
(2) third electron shell contains eighteen electrons
(3) innermost electron shell contains two electrons
(4) outermost electron shell contains eight electrons
Solution: Noble gases are elements in group 18 on the Periodic Table. Noble gases are very stable because they have a filled outer shell of electrons (8).
Answer: 4
36 A student measured the melting point of a sample of gallium to be 309 K. Based on Table S, which numerical setup can be used to calculate the student’s percent error?
Solution: Table T on the Reference Table provides us with a formula for piercer error calculation which is equal to (measured value – accepted value)/ accepted value × 100%. Student's melting point is the measured value. We can find the accepted melting point of gallium in table S.
Answer: 1
January 2020
4 The element in Group 14, Period 3, of the Periodic Table is classified as a
(1) metal (2) noble gas (3) metalloid
(4) nonmetal
Solution: Group is vertical column and period is horizontal row. The element in Group 14, Period 3 is Silicon. Silicon is on the staircase on the Periodic Table and is a metalloid.
Answer: 3
5 Which element has chemical properties that are most similar to potassium?
(1) calcium
(2) cesium (3) nitrogen
(4) sulfur
Solution: Elements in the same group (column) on the Periodic Table have similar chemical properties because they have the same number of valence electrons. Potassium is in group 1 on the Periodic Table. Cesium is group 1 as well.
Answer: 2
6 Which element requires the least amount of energy to remove the most loosely held electron from a gaseous atom in the ground state? (1) Na
(2) Ar
(3) P
(4) Cl
Solution: Ionization energy is the amount of energy needed to remove the most loosely held electron from a gaseous atom in the ground state. We can look at the ionization values on Table S for each element.
Answer: 1
10 Based on Table S, an atom of which element has the strongest attraction for electrons in a chemical bond?
(1) aluminum
(2) chlorine (3) magnesium
(4) sulfur
Solution: Electronegativity is a scale for the attraction of an element for electrons in a chemical bond. Table S provides electronegativity values for all the elements.
Answer: 2
August 2019
6 As the elements in Period 2 are considered in order from lithium to fluorine, there is an increase in the (1) atomic radius (2) electronegativity (3) number of electron shells (4) number of electrons in the first shell
Solution: Going from lithium to fluorine on the Periodic table means we are going from left to right. Atomic radius decreases going from left to right. The number of electron shells is the same for the elements in the same period. The number of electrons in the first shell is 2 for all the elements (except H) which can be seen in electron configuration on the Periodic Table. Electronegativity increases going from left to right on the Periodic Table. Alternatively, if we do not remember the trends in atomic radius or electronegativity, we can look at Table S and compare these values for a couple of elements in Period 2.
Answer: 2
7 Which element is classified as a metalloid? (1) boron
(2) potassium
(3) sulfur
(4) xenon
Solution: Metalloids are on the staircase on the Periodic Table and include: B, Si, Ge, As, Sb, Te.
Answer: 1
8 Strontium and barium have similar chemical properties because atoms of these elements have the same number of
(1) protons
(2) neutrons (3) electron shells
(4) valence electrons
Solution: Atoms with the same number of valence electrons have similar chemical properties.
Answer: 4
June 2019
8 As the first five elements in Group 14 are considered in order from top to bottom, there are changes in both the
(1) number of valence shell electrons and number of first shell electrons
(2) electronegativity values and number of first shell electrons
(3) number of valence shell electrons and atomic radii
(4) electronegativity values and atomic radii
Solution: Valence shell electrons are the same for the same group. Therefore, we can eliminate choices 1 and 3. Number of first shell electrons is always 2 (maximum), eliminating choice 2.Both electronegativity values and atomic radii change for group 14 elements.
Answer: Choice 4
33 A student measures the mass and volume of a sample of aluminum at room temperature, and calculates the density of Al to be 2.85 grams per cubic centimeter. Based on Table S, what is the percent error for the student’s calculated density of Al?
(1) 2.7%
(2) 5.3%
(3) 5.6%
(4) 95%
Solution: In Table S the density of Al is 2.70 g/cm3. % error is (measured -accepted)/accepted *100% according to Table T.
((2.85-2.70)/2.70) *100
Answer: Choice 3
34 Magnesium and calcium have similar chemical properties because their atoms in the ground state have
(1) equal numbers of protons and electrons
(2) equal numbers of protons and neutrons
(3) two electrons in the first shell
(4) two electrons in the outermost shell
Solution: Elements in the same group has similar chemical properties because they have the same number of valence electrons ( valence electrons are in the outermost shell)
Answer: Choice 4
35 As the elements in Period 2 of the Periodic Table are considered in order from left to right, which property generally decreases?
(1) atomic radius
(2) electronegativity
(3) ionization energy
(4) nuclear charge
Solution: Atomic radius decreases from left to right. If not sure, we can look at the elements in period 2 and use Table S to see the trend in atomic radius, electronegativity or ionization energy.
Answer: Choice 1
January 2019
6 The elements on the Periodic Table of the Elements are arranged in order of increasing (1) atomic number (2) mass number (3) number of neutrons (4) number of valence electrons
Solution: The elements on the Periodic Table of the Elements are arranged in order of increasing atomic number.
Answer: 1
7 Which element is malleable at STP? (1) chlorine
(2) copper
(3) helium
(4) sulfur
Solution: Malleable means that it can be hammered into sheets. Metals are malleable. Metals are located to the left of the staircase on the Periodic Table.
Answer: 2
8 At 298 K and 1 atm, which noble gas has the lowest density?
(1) Ne
(2) Kr (3) Xe
(4) Rn
Solution: Table S on the Reference Table shows the density for different elements.
Answer: 1
August 2018
5 The elements on the Periodic Table of the Elements are arranged in order of increasing (1) atomic mass
(2) formula mass (3) atomic number
(4) oxidation number
Solution: The elements on the Periodic Table of the Elements are arranged in order of increasing atomic number.
Answer: 3
6 Which element is classified as a metalloid? (1) Te
(2) S (3) Hg
(4) I
Solution: Metalloids are on the staircase on the Periodic Table and include: B, Si, Ge, As, Sb, Te.
Answer: 1
38 When a Mg2+ ion becomes a Mg atom, the radius increases because the Mg2+ ion (1) gains 2 protons
(2) gains 2 electrons
(3) loses 2 protons
(4) loses 2 electrons
Solution: Electrons are negative. When Mg2+ ion becomes a Mg atom, it gains two electrons to become neutral.
Answer: 2
January 2018
3 Which list represents the classification of the elements nitrogen, neon, magnesium, and silicon, respectively? (1) metal, metalloid, nonmetal, noble gas
(2) nonmetal, noble gas, metal, metalloid
(3) nonmetal, metalloid, noble gas, metal
(4) noble gas, metal, metalloid, nonmetal
Solution: Metals are to the left of the staircase on the Periodic Table and nonmetals are to the right of the staircase. Noble gases are in Group 18. Metalloids are on the staircase on the Periodic Table and include: B, Si, Ge, As, Sb, Te.
Answer: 2
4 In the ground state, all atoms of Group 15 elements have the same number of (1) valence electrons
(2) electron shells
(3) neutrons (4) protons
Solution: All atoms of elements that belong to the same group must have the same number of valence electrons.
Answer: 1
10 Which element tends not to react with other elements?
(1) helium
(2) hydrogen (3) phosphorus
(4) potassium
Solution: Noble gases (Group 18 on the Periodic Table) tend not to react with other elements because they have a filled octet.
Answer: 1
34 In which group on the Periodic Table would a nonmetallic element belong if atoms of this element tend to gain two electrons to complete their valence shell?
(1) 14
(2) 15 (3) 16
(4) 17
Solution: If atoms want to gain 2 electrons to complete their valence shell, we are looking for an element with -2 oxidation number (gaining two electrons is gaining two minus charges). We can look at the Periodic Table to see the oxidation numbers.
Answer: 3
35 Which trend is observed as the first four elements in Group 17 on the Periodic Table are considered in order of increasing atomic number? (1) Electronegativity increases. (2) First ionization energy decreases. (3) The number of valence electrons increases.
(4) The number of electron shells decreases.
Solution: Elements in the same group on the Periodic Table have the same number of valence electrons eliminating choice 3. The number of electron shells increases as we go down the group, eliminating choice 4. Electronegativity and Ionization energy increase going up the group. If we do not remember the trend, we can look at Table S on the Reference Table to find electronegativity values and ionization energy values for a couple of elements in Group 17 to establish the trend.
Answer: 2
June 2018
6 Which element is classified as a metalloid? (1) Cr
(2) Cs
(3) Sc
(4) Si
Solution:Metalloids are on the staircase on the Periodic Table and include: B, Si, Ge, As, Sb, Te.
Answer: 4
9 Which ion has the largest radius?
(1) Br-
(2) Cl-
(3) F-
(4) I-
Solution: Atomic radius increases to the left and down on the Periodic Table. Since all the ions have the same charge, their radius trend would remain the same.
Answer: 4
11 Based on Table S, which group on the Periodic Table has the element with the highest electronegativity?
(1) Group 1
(2) Group 2 (3) Group 17
(4) Group 18
Solution: If we look at Table S, we can look up electronegativity values for all the elements. Fluorine has the highest electronegativity. It is located in group 17
Answer: 3
June 2017
13 Compared to a potassium atom, a potassium ion has (1) a smaller radius
(2) a larger radius (3) fewer protons
(4) more protons
Solution: Potassium (K) can be found on the Periodic Table. Its' oxidation number is shown as well and is +1, which means it loses one electron. When it loses an electron, its radius becomes smaller.
Answer:1
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