Chapter 2

Rank the following elements by increasing electron affinity: barium (Ba), copper (Cu), sulfur (S), yttrium (Y).

1) Barium (Ba) 2) Yttrium (Y) 3) Copper (Cu) 4) Sulfur (S)

Rank the following elements by decreasing first ionization energy: calcium (Ca), carbon (C), germanium (Ge), and potassium (K)

1) Carbon 2) Germanium 3) Calcium 4) Potassium

In each of the following pairs, which has the larger radius? 1) F or F- 2) K or K+

1) F- > F 2) K > K+

For each of the properties listed below, write down the groups of the periodic table that exhibit those properties. 1) High reactivity with water 2) Six valence electrons 3) Contain at least one metal 4) Multiple oxidation states 5) negative oxidation states 6) Possess a full octet in the neutral state

1) Groups 1 and 2 2) Groups 6 and 16 3) Groups 1 through 15 4) All groups; most notably Groups 3 through 12 (transition metals) 5) Almost all groups; most notably Groups 14 through 17 (nonmetals) 6) Group 18

Based on their location in the periodic table, identify a the category of elements that likely possess the following properties: 1) Luster 2) Poor conductivity of heat and electricity 3) Good conductivity but brittle

1) Metals 2) Nonmetals 3) Metalloids

Rank the following elements by decreasing electronegativity: antimony (Sb), neon (Ne), oxygen (O), and thallium (Tl).

1) Oxygen (O) 2) Antimony (Sb) 3) Thallium (Tl) 4) Neon (Ne) *Remember that the first three noble gases (He, Ne, and Ar) have no measurable electronegativity.

Rank the following elements by increasing atomic radius: niobium (Nb), praseodymium (Pr), tantalum (Ta), and xenon (Xe).

1) Xenon 2) Niobium (Nb) 3) Tantalum (Ta) 4) Praseodymium (Pr)

Metals are often used for making wires that conduct electricity. Which of the following properties of metals explains why? A. Metals are malleable B. Metals have low electronegativities C. Metals have valence electrons that can move freely D. Metals have high melting points

C) Metals have valence electrons that can move freely All four descriptions of metals are true, but the most significant property that contributes to the ability of metals to conduct electricity is the fact that they have valence electrons that can move freely. Malleability (A) is the ability to shape a material with a hammer, which does not play a role in conducting electricity. The low electronegativity and high melting points of metals, (B) and (D), also do not play a major role in the conduction of electricity.

Antimony(Sb) is used in some anti parasitic medication specifically those targeting Leishmania Donovani What type of element is it? Metal Metalloid Halogen Nonmetal

Metalloid

Carbon and silicon are the basis of biological life and synthetic computing. While these elements share many chemical properties, which of the following best describes a difference between the two elements? a) Carbon has a smaller atomic radius than silicon b) Silicon has a smaller atomic radius than carbon c) Carbon has fewer valence electrons than silicon d) Silicon has fewer valence electrons than carbon

a) Carbon has a smaller atomic radius than silicon Atomic radius increases as you go down a group and decreases as you go left to right on a period.

Mendeleev's table was arranged by atomic weight, but the modern periodic table is arranged by:

atomic number

Which of the following elements has the highest electronegativity? a) Mg b) Cl c) Zn d) I

b) Cl Electronegativity increases as one moves from left to right across the period. Electronegativity decreases as one moves down the periodic table because more electron shells separate the nucleus from the outermost electrons.

When dissolved in water, which of the following ions is most likely to form a complex ion with H2O? a) Na+ b) Fe 2+ c) Cl- d) S 2-

b) Fe 2+ Iron is a transition metal. Transition metals can often form more than one ion. Iron, for example, can be Fe 2+ or Fe 3+. With these various oxidation states, transition metals can often form hydrogen complexes with water. Part of the significance of these complexes is that when a transition metal can form a complex, its solubility within the related solvent will increase. The other ions given might dissolve readily in water, but because none of them are transition metals, they will not likely form complexes.

Lithium and sodium have similar chemical properties. For example, both can form ionic bonds with chloride. Which of the following best explains this similarity? a) Both lithium and sodium ions are positively charged b) Lithium and sodium are in the same group of the periodic table c) Lithium and sodium are in the same period of the periodic table d) Both lithium and sodium have low atomic weights

b) Lithium and sodium are in the same group of the periodic table The periodic table is organized into periods (rows) and groups (columns). Groups are particularly significant because they represent sets of elements with the same valence electron configuration, which in turn will dictate many of the chemical properties of those elements.

Which of the following is an important property of the group 2 alkaline earth metal elements? a) These elements are the best electrical conductors in the periodic table. b) These elements form divalent cations c) The second ionization energy for these elements is lower than the first ionization energy d) The atomic radii of these elements decrease as one moves down the column

b) These elements form divalent cations This block represents the alkaline earth metals, which form divalent cations or ions with a +2 charge. All of the elements in Group 2 have two electrons in their outermost s-subshell. Because the loss of these two electrons would leave a full octet as the outermost shell, becoming a divalent cation is a stable configuration for all of the alkaline earth metals. Although some of these elements might be great conductors, they are not as effective as the alkali metals, eliminating a). c) is also incorrect because, although forming a divalent cation is a stable configuration for alkaline earth metals, the second ionization energy is still always higher than the first. Finally, d) is incorrect because atomic radii increase when moving down a group of elements because the number of electron shells increases.

Which property or properties increase going up a group (column) and across a period left to right? I. Electronegativity II. Atomic Radius III. First ionization energy a) I only b) I and II only c) I and III only d) II and III only

c) Electronegativity and first ionization energy Electronegativity describes how strong an attraction an element will have for electrons in a bond. A nucleus with a larger effective nuclear charge will have a higher electronegativity; Zeff increases toward the right side of a period. A strong nuclear pull will also lead to increased first ionization energy, as the forces make it more difficult to remove an electron. As size decreases, the positive charge becomes more effective at attracting electrons in a chemical bond (higher electronegativity), and the energy required to remove an electron (ionization energy) increases.

What determines the length of an element's atomic radius? I. The number of valence electrons II. The number of electron shells III. The number of neutrons in the nucleus a) I only b) II only c) I and II only d) I, II, and III

c) I and II only As one moves across a period (row), protons and valence electrons are added, and the electrons are more strongly attracted to the central protons. This attraction tightens the atom, shrinking the atomic radius. The number of electron shells is also significant, as demonstrated by the trend when moving down a group (column). As more electron shells are added that separate the positively charged nucleus from the outermost electrons, the electrostatic forces are weakened, and the atomic radius increases.

What is the highest-energy orbital of elements with valence electrons in the n =3 shell? a) s-orbital b) p-orbital c) d-orbital d) f-orbital

c) d-orbital When n = 3, l = 0, 1 or 2. The highest value for l, in this case, is 2, which corresponds to the d subshell. Although the 3d block appears to be part of the fourth period, it still has the principal quantum number n = 3. In general, the subshells within an energy shell increase in energy as follows: s < p < d < f (although there is no 3f subshell).

Ionization energy contributes to an atom's chemical reactivity. Which of the following shows an accurate ranking of ionization energies from lowest to highest? a) first ionization energy of Be < second ionization energy of Be < first ionization energy of Li b) first ionization energy of Be < first ionization energy of Li < second ionization energy of Be c) first ionization energy of Li < first ionization energy of Be < second ionization energy of Be d) first ionization energy of Li < second ionization energy of Be < first ionization energy of Be

c) first ionization energy of Li < first ionization energy of Be < second ionization energy of Be Ionization energy increases from left to right, so the first ionization energy of lithium is lower than that of beryllium. The second ionization energy is always larger than the first ionization energy, so beryllium's second ionization energy should be the highest value. This is because removing an additional electron from Be+ requires one to overcome a significantly larger electrostatic force.

Which of the following atoms or ions has the largest effective nuclear charge? a) Cl b) Cl- c) K d) K+

d) K+ The effective nuclear charge refers to the strength with which the protons in the nucleus can pull on electrons. This phenomenon helps to explain electron affinity, electronegativity, and ionization energy. In a), the nonionized chlorine atom, the nuclear charge is balanced by the surrounding electrons: 17 p+/17 e-. The chlorine ion, b), has a lower effective nuclear charge because there are more electrons than protons 17 p+/18 e-. Next, elemental potassium, c), has the lowest effective nuclear charge because it contains additional inner shells that shield its valence electrons from the nucleus. d), ionic potassium has a higher effective nuclear charge than any of the other options do because it has the same electron configuration as Cl- (and the same amount of shielding from inner shell electrons as neutral Cl) but contains two extra protons in its nucleus: 19 p+/ 18 e-.

Why do halogens often form ionic bonds with alkaline earth metals? a) The alkaline earth metals have much higher electron affinities than the halogens b) By sharing electrons equally, the alkaline earth metals and halogens both form full octets c) Within the same row, the halogens have smaller atomic radii than the alkaline earth metals d) The halogens have much higher electron affinities than the alkaline earth metals

d) The halogens have much higher electron affinities than the alkaline earth metals Ionic bonds are formed through unequal sharing of electrons. These bonds typically occur because the electron affinities of the two bonded atoms differ greatly. For example, the halogens have high electron affinities because adding a single electron to their valence shells would create full valence shells. In contrast, the alkaline earth metals have very low electron affinities and are more likely to be electron donors because the loss of two electrons would leave them with full valence electrons.

How many valence electrons are present in elements in the third period? a) 2 b) 3 c) The number decreases as the atomic number increases d) The number increases as the atomic number increases

d) The number increases as the atomic number increases Within the same period, an additional valence electron is added with each step toward the right side of the table.