Chemistry, Chapter 2

Why are the electron affinity values for the noble gases endothermic?

An electron added to a noble gas must go in the next higher energy level.

Select the TRUE statement:

Cations are smaller than their neutral parent atoms because there are fewer electrons "competing" for the attractive force of the protons in the nucleus.

Identify the largest ion.

Cl-

The periodic trend for electron affinity values is not as consistent as for other trends. Which statement best describes the trend?

Electron affinity becomes more negative going from left to right but does not have a clear trend going from top to bottom for most columns.

Noble gases are named as such because they are very unreactive. However, a few compounds are known to form with krypton and xenon. Which element will react with these noble gases to form compounds?

Fluorine

One of several trends found in the periodic table relates to metallic character. Elements that have more metallic character tend to lose valence electrons easily. Which element has the least metallic character?

Fluorine, F

Which element requires the most energy to lose one electron?

Helium has the highest first ionization energy and is the element that requires the most energy to remove one electron.

The periodic table contains a wealth of information based on how the elements are arranged. This information provides predictive power, in that chemists can extrapolate information about chemical and physical properties based on an element's position on the periodic table. For instance, the elements comprising the Noble Gases are non-reactive or inert gases. Which list of elements belongs to the family commonly called the Noble Gases?

Helium, neon, and argon

One of several trends found in the periodic table relates to the metallic character of an element. Elements that have more metallic character tend to lose valence electrons easily. Moving down the periodic table, from top to bottom, does the metallic character increase, decrease, or stay the same for the elements in the same column?

Increases

Which pair gives the more metallic element first?

K, Li

One of several trends found in the periodic table relates to ionization energy. Ionization energy is the amount of energy required to remove an electron from an atom. In the process, a cation, or positively charged ion, is formed. Which element has the smallest ionization energy?

K, potassium

Additional energy is required to move second and successive electrons from an ion. Which element could have the following series of ionization energies (IE)? IE1 = 738 kJ/mol; IE2 = 1450 kJ/mol; IE3 = 7730 kJ/mol; IE4 = 10545 kJ/mol; IE6 = 17995 kJ/mol

Magnesium

Which sequence lists the ions in order of increasing radius (smallest to largest)?

Mg2+ < Na+ < F− < O2−

One of several trends found in the Periodic Table relates to the atomic radius (the size of an atom). The radius is calculated by measuring the distance between the outer edge of the electron cloud and the nucleus. The outer edge is the last set of orbitals containing the valence electrons. Which sequence lists the atoms in order of increasing atomic radius (smallest to largest)?

O < C < Si < Al

One of several trends found in the periodic table relates to the atomic radius or the size of an atom. The radius is measured by the distance the outer edge of the electron cloud is from the nucleus. The outer edge is the last set of orbitals containing the valence electrons. Which of the following elements has the largest atomic radius?

Rubidium, Rb

The effective nuclear charge is the amount of charge experienced by an electron taking into account any shielding effects from other electrons. Electrons between the nucleus and the electron of interest cause shielding and reduce the actual charge felt by the electron of interest. Compare the outermost electron in each of the following atoms. Which one will experience the smallest effective nuclear charge?

Sodium

One of several trends found in the Periodic Table relates to the atomic radius (the size of an atom). The radius is calculated by measuring the distance between the outer edge of the electron cloud and the nucleus. The outer edge is the last set of orbitals containing the valence electrons. Which one of the following has the smallest atomic radius?

Sulfur

One of several trends found in the periodic table relates to the atomic radius or the size of an atom. The general trend in atomic radius is that moving down the periodic table, the size increases; moving across the periodic table from left to right, the size decreases. Therefore, rubidium has the largest atomic radius whereas helium has the smallest. What factor causes the atomic radius to increase while moving down the periodic table, from top to bottom?

The number of electron shells increase.

One of the several trends found in the periodic table relates to ionization energy. Ionization energy is the amount of energy required to remove an electron from an atom. In the process, a cation, or positively charged ion, is formed. Ionization energy _______ moving down the periodic table from top to bottom. In moving across the periodic table, from left to right, ionization energy _______.

decreases, increases

Alkali metals show trends, such as electron affinity and melting point, that are not typically seen in other groups of metals. Moving from lithium to cesium, the melting point _____ and the electron affinity becomes _____.

decreases; more positive

Group 7A, the halogens, show periodic trends with respect to their melting point, boiling point, and density. As you move down the column, the melting and boiling points _____ and the density _____.

increase; increases

The effective nuclear charge is the amount of charge experienced by an electron taking into account any shielding effects from other electrons. Electrons between the nucleus and the electron of interest cause shielding and reduce the actual charge felt by the electron of interest. For the outermost electron of an atom, effective nuclear charge__________ as you go from left to right on the periodic table. This is because electron shielding ___________ , due to electrons being added to the same energy level as the outermost electron.

increases, stays constant

Ions result from the gain or loss of one or more electrons. The change in the number of electrons results in a change in size for the ion as compared to the neutral atom. Anions are _____ than their neutral parent atom, and cations are _____ than their neutral parent atom.

larger; smaller