Unit 8 Readings CHEM 1215

Which type of electrons are best at shielding a 3p electron?

2p

Which electrons are removed first when forming cations of period 4 transition elements?

4s

Which of the following statements correctly describe effective nuclear charge (Zeff)? Select all that apply.

A lower Zeff makes a given electron easier to remove. The effective nuclear charge is lowered by electron-electron repulsions.

Which of the following statements correctly describe atomic radii of representative elements? Select all that apply.

Atomic radii of main group elements decrease across a period. Atomic radii generally increase as n increases.

Which of the following options correctly describe the trends in ionization energy (IE)? Select all that apply.

Atoms with low ionization energies tend to form cations. Noble gases have high ionization energies.

For the representative elements, atomic radius from left to right across a period, and from top to bottom in a group.

Blank 1: decreases, lessens, shrinks, or shortens Blank 2: increases, grows, or lengthens

The nuclear charge an electron actually experiences is called the nuclear charge (Zeff). This charge is always than the actual nuclear charge since in a many-electron system the electrons each other from the nucleus.

Blank 1: effective Blank 2: less, lower, smaller, or lesser Blank 3: shield or screen

As electrons are added to an atom, there is a(n) in electron-electron repulsions. This causes an anion of a given element to be than the neutral atom.

Blank 1: increase, rise, growth, or enlarging Blank 2: larger or bigger

Because valence electrons are effective than core electrons at shielding nuclear charge, the effective nuclear charge moving from left to right across a period of the periodic table.

Blank 1: less Blank 2: increases, rises, or grows

Mendeleev's original periodic table ordered elements by atomic , whereas the modern periodic table is ordered by atomic .

Blank 1: mass Blank 2: number or #

Main group elements tend to form ions that have the electron configurations of gases. Main group metals tend to electrons to achieve such a configuration, while main group nonmetals tend to electrons.

Blank 1: noble Blank 2: lose, give, or donate Blank 3: gain, acquire, take, accept, add, or receive

For any element in the periodic table, the number gives the n value of the highest principal energy level containing electrons. For main group elements only, the number is always equal to the number of valence electrons.

Blank 1: period or row Blank 2: group or family

Which of the following elements will have the greatest effective nuclear charge acting on its valence electrons?

Br

Based on its position in the periodic table, which of the following elements has the highest electron affinity?

Cl

Which element shown exists as a diatomic molecule in its most stable state?

Cl

Although electron affinity generally increases from left to right across the periodic table, there are some exceptions. Which of the following pairs of elements do not follow this general trend? Select all that apply.

Cl vs. Ar K vs. Ca Si vs. P

Which statement correctly describes core electrons?

Core electrons are the innermost electrons of an element.

Based on its position in the periodic table, which of the following elements has the highest electron affinity?

F

True or false: Physical properties vary predictably across a given period in the periodic table.

FALSE

Which of the following options correctly describe the exceptions to the general trend in ionization energy? Select all that apply.

Group 3A elements have lower ionization energies than 2A elements. Group 3A elements have a single electron in their outermost p subshell that is easier to remove than an s electron in the same shell.

Which of the following ions are isoelectronic with Ar? Select all that apply.

K+ Cl- S2-

Which of the following species are isoelectronic with each other? Select all that apply.

K+ S2-

Which of the following options correctly describe the general trends observed in the formation of ions by main group elements?

Metals tend to lose electrons to form cations. Ions formed from main group elements have a noble-gas electron configuration.

Which element has the lowest second ionization energy?

Mg

Which of the following elements exist as diatomic molecules in their most stable form? Select all that apply.

N, O

Which of the following elements is expected to have the highest first ionization energy, based on periodic trends?

Ne

Which statement correctly describes periodic trends in ionization energy?

Nonmetals tend to have high ionization energies.

Which monatomic ions have the electron configuration 1s22s22p6? Select all that apply.

O2- F- Na+

Using the modern periodic table, which element will have similar chemical properties to an element with Z = 7?

P

Identify the correct electron configuration, classification, and magnetic properties for a neutral atom that has 20 electrons.

Representative element Diamagnetic 1s22s22p63s23p64s2

Which of the following statements correctly describe the shielding effects in a many-electron system? Select all that apply.

Shielding reduces the nuclear charge a given electron experiences. The shielding effect increases with an increasing number of electrons in a given sublevel. Inner electrons are more effective at shielding outer electrons than electrons in the same level.

Which element listed below has the largest atomic radius?

Sr

Which of the following options classify the element mentioned correctly? Select all that apply.

Th is an actinide. Ne is a noble gas. Ca is a main group element.

Which of the following statements describe/define ionization energy correctly? Select all that apply.

The ionization energy of an element is a measure of how easily it forms a cation. Ionization energy is the energy required for the complete removal of 1 mole of electrons from 1 mole of gaseous atoms or ions.

Which of the following statements correctly describe the behavior of different groups of electrons with respect to their electron configurations? Select all that apply.

The lanthanides and actinides resemble one another because both types of elements have incompletely filled f subshells. Group 1A elements all have an outer electron configuration of ns1. Group 8A elements have filled ns and np valence subshells and are not very reactive as a result.

Which of the following options correctly describe the numbering systems used for the periodic table? Select all that apply.

The nonsequential B numbering system is used to acknowledge the similarity in the number of outer electrons for transition and main group elements. The IUPAC has suggested using a system where the groups are numbered from 1-18.

Which of the following statements correctly describe the changes that occur as we move from left to right across the periodic table? Select all that apply.

The nuclear charge increases. The number of valence electrons increases for representative elements.

Which of the following statements correctly describe the original periodic table? Select all that apply.

The original periodic table was developed by Dmitri Mendeleev. Some inconsistencies were present in the original periodic table. For example, Ar was listed as in the same group as the alkali metals. The original periodic table predicted the properties of elements that were not discovered until later. The original periodic table had 66 elements.

Why do atomic radii generally increase down a group on the periodic table?

The outer electrons are increasingly farther away from the nucleus and shielded more effectively by additional shells of inner electrons.

Which of the following statements correctly describe general trends in electron configurations? Select all that apply.

The period number of an element corresponds to the n value of the highest energy level containing electrons. Among main group elements the outer electron configurations within a group are identical.

Which of the following options correctly describe the shielding constant σ in the equation Zeff = Z - σ? Select all that apply.

The value of σ cannot be greater than the value of Z. σ cannot be equal to zero in a many-electron system.

What does it mean if two species are isoelectronic? Select all that apply.

They have the same number of electrons. They have the same electron configuration.

Which of the following statements correctly describe the formation of ions by transition metals? Select all that apply.

Transition metals first lose electrons from the ns level when forming ions. Most transition metals can form more than one cation.

Which of the following statements correctly describe the trends in ionic radii? Select all that apply.

Within an isoelectronic series of cations, ionic radius decreases with increasing nuclear charge. Ionic radius increases down a group on the periodic table. An anion is larger than its parent atom.

Atomic radius decreases from left to right across a period, a trend that can seem counterintuitive. This trend is due to the increase in ______ moving from left to right.

Zeff

Which of the following options gives the correct electron configuration for Sn4+?

[Kr] 4d10

Which of the following groups of elements have low values for electron affinity? Select all that apply.

alkali metals alkaline earth metals noble gases

For a series of isoelectronic ions such as P3-, Cl-, K+, and Ca2+, ionic radius ______ as the atomic number increases.

decrease

In general, for representative elements, atomic radii ______ from left to right across a period and ______ down a group.

decrease; increase

Two species that are described as isoelectronic have the same ______.

electron configuration

The periodic table reflects the periodic recurrence of the properties of elements. This behavior reflects the _____ of the elements.

electron configurations

For the main group elements of the periodic table, the ______ number indicates the number of ______.

group; valence electrons

Because of their common valence electron configuration, elements in the ______ group form ions with a charge of -1.

halogen

Second ionization energies are always _____ than first ionization energies because the remaining electrons are attracted _____ strongly as the positive charge on the ion increases. A large jump in ionization energies is always observed after the _____ electrons have been removed.

higher; more; valence

As we move down a group in the periodic table, both atomic and ionic radii tend to _____. Comparisons of ionic radii between groups can only be made if the species are isoelectronic. For an isoelectronic series of ions, cations are _____ than anions.

increase; smaller

As we move from left to right in the periodic table, the effective nuclear charge (Zeff) _____ because the number of _____ electrons remains the same while the actual nuclear charge increases.

increases; core

Atomic radius generally decreases from left to right across a period because the effective nuclear charge _____ while electrons are being added to the same outer level. These additional electrons are shielded _____ by inner electrons and are therefore attracted _____ strongly by the nucleus.

increases; less well; more

The main group element arsenic has an incompletely filled subshell, while the transition metal chromium has an incompletely filled subshell.

p d

In general, a given element will have a greater ionization energy than another element in the same period whose atomic radius is larger. Oxygen and nitrogen are an exception to this trend; oxygen has both a smaller radius and a lower ionization energy than nitrogen. This is because ______.

the 2p subshell of nitrogen is exactly half filled