Chapter 6 Q and A
How many valence electrons do elements in Group 1 have?
1
If a new halogen and a new noble gas were discovered, what would their atomic numbers be?
117 and 118, respectively
How many valence electrons do elements in Group 18?
8
If A and B represent the ionic radii of two elements in the same group, what is their correct order (top-to-bottom)?
A is below B. Ionic radius increases down a group.
If A and B represent the atomic radii of two elements in the same period, what is their correct order (left-to-right)?
A is to the left of B. Atomic radius in a period decreases left-to-right.
What does the dark line running between Actinium & Rutherfordium represent?
Actinide series
How many valence electrons does each of the noble gases have?
All noble gases have eight valence electrons, except for helium, which has two.
Explain why atomic radii decrease as you move left-to-right across a period.
Atomic radii decrease left-to-right because the nuclear charge increases as the shielding of inner core electrons remains constant. The increased attraction of the nucleus for its electrons pulls the electrons inward, resulting in a decreased atomic size.
Of the elements magnesium, calcium, and barium, which forms the ion with the largest radius? The smallest? What periodic trend explains this?
Ba²⁺ is the largest; Mg²⁺ is the smallest; ionic size increases down a group.
Write the electron configuration for the element fitting the following description: the metal in group 15 that is part of compounds often found in cosmetics
Bi: [Xe]6s²4f¹⁴5d¹⁰6p³
Write the electron configuration for the element fitting the following description: the halogen in period 3 that is part of a bleaching compound used in paperproduction
Cl: [Ne]3s²3p⁵
Explain how an atom's valence electron configuration determines its place on the periodic table.
Elements in a given column have the same number of valence electrons. The energy level of an atom's valence electrons determines its period.
An element forms a negative ion when ionized. On what side of the periodic table is the element located? Explain.
Elements on the right side of the periodic table gain electrons to gain a stable octet.
What is the group number of alkali metals?
Group 1
What is the group number of halogens?
Group 17
What is the group number of noble gases?
Group 18
What is the group number of alkaline earth metals?
Group 2
Give the chemical symbol of a metal used in thermometers?
Hg
Write the electron configuration for the element fitting the following description: the transition metal that is a liquid at room temperature; is sometimes used in outdoor security lights
Hg: [Xe]6s²4f¹⁴5d¹⁰
What is ionization energy?
Ionization energy is the energy needed to remove an electron from a neutral atom in its gaseous state.
What does the dark line running between Lanthanium & Hafnium represent?
Lanthanide series
Which element in each pair has the larger ionization energy? Cs, Li
Li
How was Mendeleev's periodic table in error?
Mendeleev used atomic mass instead of atomic number to order the elements. This resulted in some elements being out of order
Meyer and Mendeleev both proposed similar periodic tables in 1869. Why is Mendeleev generally given credit for the periodic table?
Mendeleev's work was published first; and he predicted properties of several yet-to-be discovered elements.
What are the general properties of metalloids?
Metalloids have properties intermediate between metals and nonmetals
Describe the general characteristics of metals.
Metals are generally dense, solid, shiny, ductile, malleable, and good conductors of heat and electricity
The figure shows two ways to define an atomic radius. Describe Method A, and identify when it is used.
Method A is used for a metal. The atomic radius is half the distance between two adjacent nuclei in a crystal of the metal.
The figure shows two ways to define an atomic radius. Describe Method B, and identify when it is used.
Method B is used for a nonmetal that occurs as a molecule. The atomic radius is half the distance between nuclei of identical atoms that are bonded together.
Which element in each pair has the larger ionization energy? Li, N
N
Which element in each pair has the larger ionization energy? Kr, Ne
Ne
Explain the contribution of Newland's law of octaves to the development of the modern periodic table.
Newlands introduced the idea of periodically repeating properties
Give the chemical symbol of a transition metal that is the name of a coin?
Ni
Do any of the halogens have their valence electrons in orbitals of the same energy level? Explain.
No. Each halogen is in a different period; therefore, each has its valence electrons in orbitals of a different energy level.
The electron configuration of a chlorine atom is [Ne]3s²3p⁵. When it gains an electron and becomes an ion, its electron configuration changes to [Ne]3s²3p⁶, or [Ar], the electron configuration for argon. Has the chlorine atom changed to an argon atom? Explain.
No; the electron configurations of a chlorine ion and an argon atom are the same, but the chlorine ion still has 17 protons and retains its identity as chlorine.
The transition elements have their valence electrons in orbitals of more than one energy level, but the representative elements have their valence electrons in orbitals of only one energy level. Show this by using the electron configurations of a transition element and a representative element as examples.
Possible answer: The electron configuration of chlorine (a representative element) is [Ne] 3s²3p⁵, which has its valence electrons in orbitals of the third energy level. The electron configuration of iron (a transition element) is [Ar]4s²3d⁶, which has its valence electrons in orbits of both the third and fourth energy levels.
Give the chemical symbol of the noble gas with the greatest atomic mass?
Rn
Give the chemical symbol of a coating for food cans?
Sn
How is the energy level of an atom's valence electrons related to the period it is in on the periodic table?
The energy level of an atom's valence electrons equals its period number.
If A is an ion and B is an atom of the same element, is the ion a positive or negative ion?
The ion is negative. A negative ion is always larger than its atom.
How does the ionic radius of a nonmetal compare with its atomic radius? Explain the change in radius.
The ionic radius of a nonmetal is larger than its neutral atom. Nonmetals tend to gain electrons in the atom's current energy level; these additional electrons repel each other and increase the size of the ion.
Explain the octet rule. Why are the first period elements, hydrogen and helium, exceptions to the octet rule?
The ns2np6 electron configuration, known as the octet configuration, contains eight electrons and generally has the lowest energy and is the most stable. Atoms gain, lose, or share electrons in order to obtain the stable octet configuration. They have a complete energy level with just two valence electrons.
Why do the elements chlorine, used in laundry bleach, and iodine, a nutrient added to table salt, have similar chemical properties?
They have the same valence electron configuration (s²p⁵)
What is the periodic law?
When the elements are arranged by increasing atomic number, there is a periodic repetition of their chemical and physical properties.
Explain why each successive ionization of an electron requires a greater amount of energy.
With each removed electron, there are fewer electrons to shield the remaining electrons from the electrostatic force of attraction of the nucleus. The increased nuclear attraction makes it more difficult to remove subsequent electrons.
One of the transition groups is often called the coinage group because at one time many coins were made of these metals. Which group is this? What elements in this group are still used in many U.S. coins today?
group 11; copper, silver, gold
Determine the group, period, and block in which each of the following elements is located in the periodic table: [Ne]3s²3p¹
group 13, period 3, p-block
Determine the group, period, and block in which each of the following elements is located in the periodic table: [Ar]4s²3d¹⁰4p³
group 15, period 4, p-block
Determine the group, period, and block in which each of the following elements is located in the periodic table: [He]2s²2p⁶
group 18, period 2, p-block
Determine the group, period, and block in which each of the following elements is located in the periodic table: [Kr]5s²4d¹
group 3, period 5, d-block
Given any two elements within a group, is the element with the larger atomic number likely to have a larger or smaller atomic radius than the other element?
larger
Metal, nonmetal, or metalloid? barium
metal
Metal, nonmetal, or metalloid? iron
metal
Metal, nonmetal, or metalloid? germanium
metalloid
Metal, nonmetal, or metalloid? Oxygen
nonmetal
What electron configuration has the greatest stability?
ns²np⁶, where n is the energy level
What are the four blocks of the periodic table?
s-, p-, d-, and f-block
