CHE 170 Chapter 7 Homework

Which pair lists the element with the lower first ionization energy first? A. Magnesium, Calcium B. Helium, Neon C. Oxygen, Fluorine D. Chlorine, Sulfur

C. Oxygen, Fluorine

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

True

Elements have a series of ionization energies for removing the first and additional electrons from the atom. Each ionization energy increases for successive electrons being removed. Where will the largest jump in ionization energies occur for aluminum?

between the third and fourth ionization energies Aluminum has three valence electrons. Removing the fourth electron will require significantly more energy due to the necessity of removing a core electron.

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

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 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.

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 This indicates that removal of the third electron will be removing a core electron rather than a valence electron. The first two ionization energies, which are before the large increase, are for the removal of the valence electrons. Magnesium has two valence electrons and could have this set of ionization energies. Sodium has one valence electron and will have a large increase after the first ionization energy. Chlorine has seven valence electrons and will have a large increase after the seventh ionization energy. Nitrogen has five valence electrons and will see a large increase after the fifth ionization energy.

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? A. Rb B. Xe C. Ne D. Li

Rb. Rubidium

The outermost electron of boron experiences a lower effective nuclear charge than carbon. Why?

The nuclear charge increases from boron to carbon, but there is no additional shielding Going from boron to carbon, the nuclear charge is increasing due to the addition of a proton to the nucleus. There is no additional shielding because the addition of an electron is to the same energy level. Therefore there is no increase in shielding due to additional electrons. As a result, the outermost electron of boron will experience a lower effective nuclear charge than the outermost electron of carbon.

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 The electron affinities for the alkali metals becomes more positive going from top to bottom of the periodic table while the melting points decrease.

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, increase

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 one of the following statements is true regarding ionization energies?

ionization energies are all endothermic

Anions are _____ than their neutral parent atom cations are _____ than their neutral parent atom.

larger; smaller

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?

potassium Effective nuclear charge decreases going down a column and increases from left to right.

What is the effective nuclear charge?

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

What factor causes the atomic radius to increase while moving down the periodic table, from top to bottom?

the number of electron shells increase

Group 1A Metals react vigorously with halogens. What equation best represents the reaction of Sodium and Bromine?

2Na + Br2 → 2NaBrBromine is a diatomic element that reacts vigorously with sodium metal to produce NaBr. Other alkali metals will react with halogens in a similar manner. The reaction will not produce atomic bromine because it is not a stable form of bromine. Based on the ions formed by sodium and bromine, the ratio of the resulting compound must be 1:1 in order to form a neutral ionic compound.

Which element is the most metallic? A. Cs B. O C. Mn D. Si

A. Cs

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? A. Fluorine B. Sulfur C. Sodium D. Chlorine

A. Fluorine Xenon and krypton can react with fluorine, the most reactive nonmetal, under fairly extreme circumstances, to produce a small number of compounds. Xenon can also form compounds with oxygen, but in general, the noble gases are very unreactive and can be used when an inert gas is needed

Compare the outermost electron in each of the following atoms. Which one will experience the smallest effective nuclear charge? A. Beryllium B. Calcium C. Potassium D. Sodium

A. Potassium Effective nuclear charge decreases going down a column and increases from left to right. Therefore, the outermost electron of potassium will experience the lowest effective nuclear charge

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

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? A. Silicon B. Sulfur C. Sodium D. Selenium

B. Sulfur

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? A. Kr B. Ne C. K D. H

C. K, Potassium

Electron affinity is the energy associated with the gain of an electron by an atom in the gaseous state. Which element will release the most energy when gaining an electron?

Chlorine

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? A. Si B. Cs C. Na D. F

D. Fluorine

the periodic trend for electron affinity values is not as consistent as for the 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.

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.