Unit 9: Periodic Trends

All of these are factors that affect the effective nuclear charge, Zeff, EXCEPT A) mass number B) the type of orbital an electron occupies C) the number of core electrons D) the number of valence electrons E) atomic number

A) mass number

Which of the following radii comparisons is incorrect? A) Sr²⁺ < Sr B) Br⁻ < Br C) Fe³⁺ < Fe²⁺ D) Se²⁻ > Se E) Sn²⁺ > Sn⁴⁺

B) Br⁻ < Br

Which periodic trend quantifies the amount of energy required to remove an electron from a neutral, gaseous atom? A) Atomic Radius B) Ionization Energy C) Ionic Radius D) Electron Affinity E) Electronegativity

B) Ionization Energy

Which of the following atom(s) below has/have five valence electrons? A) C B) N C) O D) F E) All of the above

B) N

Which of the following would you expect to have the most negative (most exothermic) electron affinity? A) Li B) O C) K D) Se E) Rb

B) O

Which of the following would you expect to have the most negative (most exothermic) electron affinity? A) Si B) S C) Cl D) Sn E) I

C) Cl

All of the following pairs of ions are isoelectronic except which one? A) Al³⁺ and N³⁻ B) Fe²⁺ and Co³⁺ C) Fe²⁺ and Mn³⁺ D) K⁺ and Ca²⁺ E) Zn²⁺ and Cu⁺

C) Fe²⁺ and Mn³⁺

The trend towards smaller atomic radii as one moves to the right in a period is _____. A) faulty, as atomic radii in a period are nearly uniform in size. B) because of electron pair repulsion causing the expansion of the orbitals. C) wrong. Atomic radii increase across a period left to right as the larger d and p orbitals are occupied after the s orbital. D) due to the effective nuclear charge decreasing. E) due to the effective nuclear charge increasing.

E) due to the effective nuclear charge increasing.

are ionization processes exothermic or endothermic?

always exothermic and IE is always positive

Which atom has is larger based on its periodic trend? 1. Sb or Bi 2. Sr or Te 3. Cr or Cr³⁺ 4. Se²⁻ or Te²⁻

1. Bi 2. Sr 3. Cr 4. Te²⁻

Consider the atoms P, Br, and Ba. 1. Which atom would have the greatest electron affinity? 0.33 of 0.33 points earned 2. Which atom would have the highest effective nuclear charge for its 1s electrons? 0.33 of 0.33 points earned 3. Which atom would have the largest atomic radius? 0.33 of 0.33 points earned

1. Br 2. Ba 3. Ba

Which haas a higher first ionization energy? 1. Al or Si 2. Mg or S 3. Sr or O

1. Si 2. S 3. O 4. K

Which of the following pairs of ions have the same total number of electrons? A) Cl⁻; Ca²⁺ B) Mg²⁺; Ca²⁺ C) Mg²⁺; Fe²⁺ D) Pb⁴⁺; Ba²⁺ E) F⁻; Li⁺

A) Cl⁻; Ca²⁺

Under which process does an atom demonstrate the largest increase in size in one step? A) Gaining its first electron to become a -1 anion. B) Gaining its second electron to become a -2 anion. C) The size of an atom is constant. D) Losing its first electron to become a +1 cation. E) Losing its second electron to become a +2 cation.

A) Gaining its first electron to become a -1 anion.

Which of the following groups of elements tend to form cations? A) Metals B) Metalloids C) Nonmetals D) Noble gases E) Radioactive elements

A) Metals

Which of the following elements would have a very different electron affinity value compared to the others? A) Ne B) Al C) O D) F E) Na

A) Ne

Which of the following radii comparisons is correct? A) N³⁻ < N B) Ti⁴⁺ > Ti³⁺ C) In³⁺ < In⁺ D) C⁴⁺ > C⁴⁻ E) As³⁻ < As³⁺

C) In³⁺ < In⁺

Which of the following is true concerning successive ionizations of an atom and its ions? A) Each successive ionization requires less energy to achieve. B) All ionizations require the same amount of energy. C) The amount of energy required to achieve a successive ionization doubles with each electron removed. D) Each successive ionization requires increasing amounts of energy. E) The first two ionizations are endothermic but each ionization afterwards is exothermic.

D) Each successive ionization requires increasing amounts of energy.

Which of the following series of isoelectronic ions (Mg²⁺, N³⁻, F⁻, Si⁴⁺) has the ionic radii in order of largest to smallest? A) Mg²⁺ > N³⁻ > F⁻ > Si⁴⁺ B) Mg²⁺ > Si⁴⁺ > F⁻ > N³⁻ C) N³⁻ > F⁻ > Si⁴⁺ > Mg²⁺ D) N³⁻ > F⁻ > Mg²⁺ > Si⁴⁺ E) F⁻ > N³⁻ > Si⁴⁺ > Mg²⁺

D) N³⁻ > F⁻ > Mg²⁺ > Si⁴⁺

Rank the following atoms in order of increasing size (i.e., smallest to largest): Li, Al, Be, Ba, O. A) Li < Al < Be < Ba < O B) Ba < Al < Li < Be < O C) Li < Be < O < Al < Ba D) O < Be < Li < Al < Ba E) O < Li < Be < Ba < Al

D) O < Be < Li < Al < Ba

how do cations and anions' radii compare?

cations have a smaller radius due to lost electrons; increased electrons results in anions having a larger radius than the parent atom

what types of orbitals are energetically favorable?

half-filled orbitals

covalent radius

one-half the distance between the nuclei of two identical atoms when they are joined by a covalent bond

electron affinity

the energy needed to remove an electron from a negative ion to form a neutral atom or molecule

ionization energy (IE)

the energy required to remove an electron from a gaseous atom in its ground state

first and second ionization energy

the energy required to remove the most loosely bound electron from a gaseous atom in its ground state

effective nuclear charge

the net positive charge experienced by valence electrons

Rank the following atoms in order of decreasing size (i.e., largest to smallest): Rb, F, Mg, B, N. A) Rb > Mg > B > N > F B) N > F > B > Mg > Rb C) Rb > Mg > F > N > B D) Mg > Rb > B > N > F E) Rb > Mg > N > B > F

A) Rb > Mg > B > N > F

Which has a higher ionization energy? A) Rb⁺ B) Sr⁺

A) Rb⁺

Which has the smallest size? A) Cs⁺ B) Ba²⁺

B) Ba²⁺

In which direction on the periodic table does metallic character increase? A) Down and to the right. B) Down and to the left. C) As you move toward the middle of the table. D) Up and to the right. E) Up and to the left.

B) Down and to the left.

The energy released in the reaction F(g) + e⁻ → F⁻(g) is known as the A) Ionization energy B) Electron affinity C) Enthalpy of ionization D) Electronegativity E) Enthalpy of electronegativity

B) Electron affinity

Rank the following atoms in order of decreasing first ionization energies (i.e., highest to lowest): Li, Be, Ba, F. A) Ba > Li > Be > F B) F > Be > Li > Ba C) Li > Be > F > Ba D) F > Be > Ba > Li E) Ba > F > Be > Li

B) F > Be > Li > Ba

Which has the greatest electron affinity? A) Xe B) I

B) I

Halogens tend to form anions because A) losing electrons will fill their octet faster than gaining them. B) gaining electrons will fill their octet faster than losing them. C) halogen element ionization energies are lower than transition metal ionization energies. D) halogen atomic radii tend to be larger than their corresponding ionic radii. E) halogen atomic radii tend to be smaller than their corresponding ionic radii.

B) gaining electrons will fill their octet faster than losing them.

Elements that are most similar in their properties are found _____ A) in the same period. B) in the same group. C) have the same electron configurations. D) to occur randomly throughout the table. E) diametrically opposite each other on the periodic table.

B) in the same group.

How many core electrons does an atom of beryllium (Be) contain? A) 0 B) 1 C) 2 D) 3 E) 4

C) 2

The first five ionization energies of an element are as follows (in kJ/mol): 577.9, 1820, 2750, 11600, 14800. Which of the following elements is most likely to have these ionization energy values? A) Na B) Mg C) Al D) Si E) P

C) Al

Valence electrons in which of the following atoms experience the greatest effective nuclear charge (Zeff)? A) Cl B) Ar C) F D) Ne E) B

D) Ne

Rank the following atoms in order of increasing first ionization energies (i.e., lowest to highest): Rb, F, Mg, B, N. A) F < N < B < Mg < Rb B) Rb < Mg < F < N < B C) Mg < Rb < F < N < B D) Rb < Mg < B < N < F E) Rb > B > N > F > Mg

D) Rb < Mg < B < N < F

Which of these statements is true concerning the following reaction? Na(g) → Na⁺(g) + e⁻. A) The energy required is the electron affinity B) The reaction is exothermic C) Na⁺(g) is an anion D) This is an ionization process.

D) This is an ionization process.

Effective nuclear charge, Zeff, is defined as A) the number of protons minus the number of valence electrons. B) the difference in electronegativities of two bonded atoms or ions. C) the number of protons minus the number of electrons. D) the true nuclear charge minus the charge that is shielded by electrons. E) the number of protons in the nucleus.

D) the true nuclear charge minus the charge that is shielded by electrons.

For an atom of carbon, which ionization will exhibit a very large increase in the energy relative to the preceding ionization? A) 1st B) 2nd C) 3rd D) 4th E) 5th

E) 5th

Which of the following elements has the smallest first ionization energy? A) S B) O C) Si D) Sr E) Cs

E) Cs

Which of the following metals would be expected to have the smallest atomic radius? A) Cesium (Cs) B) Barium (Ba) C) Lanthanum (La) D) Europium (Eu) E) Tantalum (Ta)

E) Tantalum (Ta)

is electron affinity exothermic or endothermic?

negative EA values

shielding

shielding occurs when inner electrons partially shield outer electrons from the nucleus

ionic radius

size of an ion