Mastering Chemistry - Ch. 7
The shielding of electrons gives rise to an effective nuclear charge, Zeff, which explains why boron is larger than oxygen. Estimate the approximate Zeff felt by a valence electron of boron and oxygen, respectively?
+3 and +6 The valence electrons in an oxygen atom are attracted to the nucleus by a positive charge nearly double that of boron. Therefore, the electrons in oxygen are held closer to the nucleus, giving it a smaller radius.
Which group is likely to react with chlorine to form compounds in the form XCl?
1
Potassium metal is exposed to an atmosphere of chlorine gas.
2K(s)+Cl2(g)→2KCl(s)
Sodium metal reacts with molten sulfur.
2Na(s)+S(l)→Na2S(s)
Consider the following neutral electron configurations in which n has a constant value. Which configuration would belong to the element with the most negative electron affinity, E_ea?
2s^22p^5
A fresh surface of lithium metal is exposed to oxygen gas.
4Li(s)+O2(g)→2Li2O(s)
Which element is most likely to react with oxygen?
Aluminum
The red stepped line divides metals from nonmetals. How are common oxidation states divided by this line?
Anions are above the line; cations are below the line.
What element XX is most likely to react to form the compound XF5?
Antimony
A main group metal was studied and found to exhibit the following properties: It does not occur free in nature. It loses valence electrons readily. It reacts readily with the halogens, oxygen, and nitrogen. It is produced by high-temperature reduction of its oxide. It reacts vigorously with water. Which of the following metals might have been the element studied?
Ba
A certain element has a melting point over 700 ∘C∘C and a density less than 2.00 g/cm3. Give one possible identity for this element.
Be Based on the information given, the unknown element is either calcium or beryllium.
Which halogen is a liquid at room temperature?
Bromine
Arrange the elements S, P, Cl, and Ca in order of increasing electronic affinity (EA).
Ca<P<S<Cl
Which of the following correctly lists nonmetals that exist under ordinary conditions as diatomic molecules?
Cl, Br, F, O
Who is considered the founder of the periodic table of the elements?
Dmitri Mendeleev
Copper, silver, and gold have all been know since ancient times because they appear in nature in ____________ and were thus discovered thousands of years ago
Elemental Form
What is the reaction that corresponds to the electron affinity of fluorine, F?
F+e−→F−
Of the well-characterized elements of group 7A, which would exhibit the following properties? It reacts with the alkali metals (M) to form a salt MX, where X is the halogen. Its hydrogen halide, HX, forms a weakly acidic solution. It is more reactive than the other halogens. It forms interhalogen compounds only of the form XA, where A is the unknown and X is another halogen.
Fluorine
Arrange the following elements from greatest to least tendency to accept an electron.
Greatest --> Least F, O, C, Li, Be The tendency to gain an electron is quantitatively measured by the electron affinity, the amount of energy involved in the addition of an electron to a neutral gaseous atom. Ordering these elements by the electron affinity provides an identical order: F>O>C>Li>Be
Why are the electron affinities of the Group 4A elements more negative than those of the Group 5A elements?
Group 5A half-filled pp-subshells discourage addition of an electron.
Elements of group 8A of the periodic table are known as the noble gases. Determine which of the following properties are characteristic of all naturally occurring noble gases
Have a large ionization energy
A sample of soil from a newly discovered cave is analyzed by a team of explorers. They find an element that is a good conductor of electricity. It also forms a chloride in the form XCl2 and an oxide in the form XO. The element is a liquid at room temperature. What is the identity of this element?
Hg
For the series of elements XX, YY, and ZZ all in the same period (row), arrange the elements in order of decreasing first ionization energy. ElementRadius(pm)X124 Y 179 Z 257
Highest --> Lowest Element X, Element Y, and Element Z The inward "pull" on the electrons from the nucleus is called the effective nuclear charge. When looking at a series of atoms within the same period, the greater the pull on the electrons, the smaller the atom and the harder it is to remove an electron.
Arrange the elements in decreasing order of first ionization energy.
Highest --> Lowest Se, Ge, In, Cs
Which of the following correctly describes the measurement of an atom's electron affinity?
It measures the ease with which an atom gains an electron.
Na, Ra, and Sr: Rank elements from largest atomic radius to smallest atomic radius.
Larges --> Smallest Ra, Sr, Na
H, B, and C: Rank elements from largest atomic radius to smallest atomic radius.
Largest --> Smallest B, C, H
Se, Sn, and Sb: Rank elements from largest atomic radius to smallest atomic radius.
Largest --> Smallest Sn, Sb, Se
Rank the following elements in order of decreasing atomic radius.
Largest --> Smallest Rb, K, Na, Li
Rank the following elements in order of decreasing atomic radius.
Largest --> Smallest Si, P, S, Cl
What is the reaction that corresponds to the first ionization energy of lithium, Li?
Li(g)→Li+(g)+e−
How do the periodic trends in metallic character compare to those for ionization energy?
Metals tend to have lower ionization energies than nonmetals.
A compound ACl3 (A is an element) has a melting point of -112 ∘C. Would you expect the compound to be molecular or ionic?
Molecular
Moving from boron to aluminum?
Moving from boron to aluminum, the intensity of the bulb increases because Z increases from 5 to 13. The thickness of the frosting also increases because A l has the core configuration of Ne, while B has the core of He.
Moving from boron to carbon?
Moving from boron to carbon, the intensity of the bulb increases because Z increases from 5 to 6. The thickness of the frosting stays the same because the core electron configuration is the same for both atoms.
Which element has the following configuration: [Xe]6s^24f^4?
Nd
Which of the following shows a correct relationship between first ionization energies of the given atoms?
Ne > F
An element X reacts with F2(g) to form the molecular product shown here. Do you think that X is a metal or nonmetal?
Nonmetal X is a nonmetal because it contains fluorine and it creates an anion. Submit
Given Br, O, S, F, and Cl atoms, arrange them in order of increasing ability to accept electrons to form anions in reactions.
O < S < Br < F < Cl
A compound ACl3 (A is an element) has a melting point of -112 ∘C. If you were told that AA is either scandium or phosphorus, which do you think is the more likely choice?
PCl3
Predict the product(s) of the following reaction: Cs + Br2 ⇌ The equation is not necessarily balanced.
Product of Cs + Br2 is 2CsBr Since all ionic compounds have a neutral charge, metal halides of alkali metals have a 1:1 ratio between alkali metal and halogen.
Predict the products of the following reaction: Rb + N2⇌ The equation is not necessarily balanced.
Product of Rb + N2Rb + N2 is no reaction
If we had potassium vapor lamps, what color would they be?
Purple
Place the following elements in order of decreasing atomic size: selenium, chlorine, fluorine, rubidium, calcium, and sulfur.
Rb, Ca, Se, S, Cl, F
But the majority of elements ____________ and, consequently, are hard to find in nature.
Readily Form Compounds
Which sphere represents a metal and which a nonmetal?
Red sphere represents a metal, the blue sphere represents a nonmetal. The red sphere represents a metal because it loses electrons in the reaction and turns into a cation.
Would you expect rubidium metal to be more or less reactive with water than potassium metal?
Rubidium metal is more reactive with water than potassium metal.
Metalloids have properties intermediate between those of metals and nonmetals. An example of a metalloid is _____.
Sb
Strontium oxide is added to water.
SrO(s)+H2O(l)→Sr(OH)2(aq)
Predict the relative reducing power of the group 2A elements.
Strongest --> Weakest Ba, Sr, Ca, Mg, Be
Gaseous hydrogen halide compounds dissolve in water to form the hydrohalic acids. Use periodic trends to rank the hydrohalic acids in order of strength.
Strongest --> Weakest Hl, HBr, HCl, HF It important to note that concentration, not strength, is generally the best indication of the corrosiveness of an acid solution. A concentrated weak acid can be far more dangerous than a dilute strong acid.
Another element is silvery-white with a shiny luster, is very brittle, and forms ions with a −2 charge. Give one possible identity of this element.
Te Tellurium is the only metalloid in group 6A, and therefore it is the only possible identity for this element.
Which of the following occurs upon moving from left to right across a period (row) of elements on the periodic table?
The effective nuclear charge increases.
In 1913, the English physicist Henry Moseley developed the concept of atomic numbers. He correctly identified the atomic number with which of the following?
The number of protons in the nucleus of the atom and the number of electrons in the atom
Which is not a characteristic of metals?
They are poor conductors of heat and electricity.
An element belongs to Group 9. What common name might be used to describe the group to which this element belongs?
Transition Metal
An element X reacts with F2(g) to form the molecular product shown here. Write a balanced equation for this reaction (do not worry about the phases for X and the product) .
X + 2F2 → XF4
What is the ground state electronic configuration of Ti+4?
[Ar]
What is the ground-state electron configuration of the chloride ion Cl−?
[Ar]
What is the ground-state electron configuration of a neutral atom of nickel?
[Ar]3d^84s^2
Which would you expect to experience a greater effective nuclear charge?
a 2p electron of a Ne atom
Which part of the periodic table has the elements with the largest atoms?
bottom and left
In the group 3 to group 12 elements, which subshell is filled up going across the rows?
d subshell In the group 3 to group 12 transition metals, the outermost s electron shell contains one or two electrons. However, in these metals, it is the d subshells that fill up going across the row. In period 4 of the table, the 3d subshell fills, and in periods 5 and 6, the 4d and 5d subshells fill, respectively. It is important to keep in mind that this filling is not always regular. For example, in period 4, element 23, vanadium, has an electron configuration of [Ar]3d34s2, but element 24, chromium, has an electron configuration of [Ar]3d54s.
The ionization energy for lithium is 520 kJ/molkJ/mol. The electron affinity for fluorine is -328 kJ/molkJ/mol. Use these values and Hess's law to calculate the change in enthalpy for the following reaction per mole of reagent: Li(g)+F(g)→Li+(g)+F−(g), ΔH=?
ΔHDelta H per mole =192 kJ This is an endothermic reaction, as indicated by a positive enthalpy change.
