exam 3 take 2

How many electrons should be shown in the Lewis dot structure for hydrogen?

1

How many resonance structures can be drawn for ozone, O3?

2

Determine the number of bonding electrons and the number of nonbonding electrons in the structure of SI2.

4,16

An atom has the electron configuration 1s22s22p63s23p 3 . How many valence electrons does the atom have?

5

How many valence electrons does a nitrogen atom possess?

5

Using the equation Zeff=Z−S and assuming that core electrons contribute 1.00 and valence electrons contribute 0.00 to the screening constant, S, calculate Zeff for the 2p electrons in both ions.

7,9 e−

Determine the number of bonding electrons and the number of nonbonding electrons in the structure of CO2.

8,8

Why are ionization energies always positive quantities?

According to Coulomb's law, the energy of an electron in an atom is negative, because of the electrostatic attraction of the electron for the nucleus. In order to overcome this attraction, remove the electron and increase its energy; energy must be added to the atom. Ionization energy, DeltaE for this process, is positive, regardless of the magnitude of Z or the quantum numbers of the electron.

Rank items from the element with the largest atomic radius to the element with the smallest one. Al, Be, Si.

Al, Si, Be

What is an isoelectronic series?

An isoelectronic series is a group of atoms or ions that have the same number of electrons, and thus the same electron configuration.

Based on their positions in the periodic table, predict which atom of the following pairs will have the larger first ionization energy. Cl, Ar

Ar

For isoelectronic ions, how are effective nuclear charge and ionic radius related?

As nuclear charge (Z) increases, ionic radius decreases.

Rank items from the element with the largest atomic radius to the element with the smallest one. Ba, Ca, Na

Ba, Ca, Na

Based on their positions in the periodic table, predict which atom of the following pairs will have the larger first ionization energy. Be, Ca

Be

For each of the following pairs, indicate which element has the larger first ionization energy. Ge, Cl

Cl

Based on their positions in the periodic table, predict which atom of the following pairs will have the larger first ionization energy. K, Co

Co

Which element in the periodic table has the smallest ionization energy?

Cs

Rank the following ions in order of decreasing radius: Rb+, K+, Li+, Cs+, and Na+.

Cs+, Rb+, K+, Na+, Li+

For each of the following pairs, indicate which element has the larger first ionization energy. Ag, Cu

Cu

Why are monatomic cations smaller than their corresponding neutral atoms?

Electrostatic repulsions are reduced by removing an electron from a neutral atom, Z_eff increases, and the cation is smaller.

Explain any differences in the orders of the atomic and ionic sizes.

Even though K has the largest Z value, the n-value of the outer electron is larger than the n-value of valence electrons in S and Cl so K atoms are largest. When the 4s electron is removed, K^+ is isoelectronic with Cl^- and S^2-. The larger Z value causes the 3p electrons in K^+ to experience the largest effective nuclear charge and K^+ is the smallest ion.

In the molecule FBr, which atom is the negative pole?

F

Why does F have a larger first ionization energy than O?

F has a greater first ionization energy than O, because F has a greater Z_eff and the outer electrons in both elements are approximately the same distance from the nucleus.

Write equations that show the process for the first two ionization energies of tin.

First stage: Sn(g)→Sn+(g)+e− Second stage: Sn+(g)→Sn2+(g)+e−

Why does the size of ions increase as one proceeds down a column in the periodic table?

Going down a column, the n value of the valence electrons increases and they are farther from the nucleus. Valence electrons also experience greater shielding by core electrons. The greater radial extent of the valence electrons outweighs the increase in Z, and the size of particles with like charge increases.

Which element in the periodic table has the largest ionization energy?

He

Which neutral atom is isoelectronic with Bi3+?

Hg

What is the general relationship between the size of an atom and its first ionization energy?

In general, the smaller the atom, the larger its first ionization energy.

List the atom in order of decreasing size. S, Cl, K

K, S, Cl

K+ is larger than Ca2+. Explain

K^+ is larger than Ca^2+ because for isoelectronic ions, the ion with the smaller Z has the larger radius.

Which neutral atom is isoelectronic with Se2−?

Kr

Which ion is smaller? F-, Na+

Na+

Rank the following items in order of decreasing radius: Na, Na+, and Na−.

Na-, N, N+

Which neutral atom is isoelectronic with N3−?

Ne

Based on position in the periodic table and electron configuration, arrange these elements in order of decreasing Ei1. K, O, Na, P, Al, S.

O, P, S, Al, Na, K

O2− is larger than O; Explain

O^2- is larger than O because the increase in electron repulsions that accompany addition of an electron causes the electron cloud to expand.

Of the molecules PF3 and PCl3, which has bonds that are more polar?

PF3

Based on their positions in the periodic table, predict which atom of the following pairs will have the larger first ionization energy. S, Ge

S

List the ions in order of decreasing size. S2−, Cl−, and K+

S2-, Cl-, K+

S2− is larger than K+; Explain

S^2- is larger than K^+ because the two ions are isoelectronic and K^+ has the larger Z and Z_eff.

S2− is larger than O2−; Explain

S^2- is larger than O^2-, because for particles with like charges, size increases going down a family.

For each of the following pairs, indicate which element has the larger first ionization energy. Pb, Sb

Sb

The difference between the third and fourth ionization energies of scandium is much larger than the difference between the third and fourth ionization energies of titanium. Why?

Sc: [Ar]4s^23d^1; Ti: [Ar]4s^23d^2. The fourth ionization of titanium involves removing a 3d valence electron, while the fourth ionization of Sc requires removing a 3p electron from the [Ar] core. The effective nuclear charges experienced by the two 3d electrons in Ti are much more similar than the effective nuclear charges of a 3d valence electron and a 3p core electron in Sc. Thus, the difference between the third and fourth ionization energies of Sc is much larger.

Rank items from the element with the largest atomic radius to the element with the smallest one. Sn, Sb, As.

Sn, Sb, As

Based on their positions in the periodic table, predict which atom of the following pairs will have the larger first ionization energy. Sn, Te

Te

Why are monatomic anions larger than their corresponding neutral atoms?

The additional electrostatic repulsion produced by adding an electron to a neutral atom causes the electron cloud to expand, so that the radius of the anion is larger than the radius of the neutral atom.

Why does Li have a larger first ionization energy than Na?

The effective nuclear charges of Li and Na are similar, but the outer electron in Li has a smaller n-value and is closer to the nucleus than the outer electron in Na. More energy is needed to overcome the greater attraction of the Li electron for the nucleus.

Why does Li have a much larger second ionization energy than Be?

The electron configuration of Li^+ is 1s^2 or [He] and that of Be^+ is [He]2s^1. Be^+ has one more valence electron to lose while Li^+ has the stable noble gas configuration of He. It requires much more energy to remove a 1s core electron close to the nucleus of Li^+ than a 2s valence electron farther from the nucleus of Be^+.

Why is the second ionization energy of an atom always greater than its first ionization energy?

The second ionization energy of an element is greater than the first because Z_eff is larger for the +1 cation than the neutral atom; more energy is required to overcome the larger Z_eff.

How are metallic character and first ionization energy related?

The smaller the first ionization energy of an element, the greater the metallic character of that element.

For each of the following pairs, indicate which element has the larger first ionization energy. Ti, Ba

Ti

Write equation that shows the process for the fourth ionization energy of titanium.

Ti3+(g)→Ti4+(g)+e−

What are valence electrons?

Valence electrons are those that take part in chemical bonding, those in the outermost electron shell of the atom. This usually means the electrons beyond the core noble-gas configuration of the atom, although it is sometimes only the outer shell electrons.

Which neutral atom is isoelectronic with Ba2+?

Xe

Both of the carbon-oxygen double bonds in CO2 are polar. In which direction should the polarity arrows point?

away from the central carbon atom

Carbon tetrachloride (CCl4) is used as a propellant in aerosol cans. What type of bonding occurs between the atoms of a CCl4 molecule?

covalent

What type of bonding occurs in iron(III) chloride, FeCl3?

ionic

What type of bonding occurs in a sample of pure sodium, Na? In other words, how is one sodium atom held to another sodium atom?

metallic