Lesson 3: Practice Exercises

How many valence electrons are in an atom of each of the following elements? a) Ne b) Br c) S d) Sr e) Na f) As g) Sn h) In

A. 8 B. 7 C. 6 D. 2 E. 1 F. 5 G. 4 H. 3

Select the symbol of the element that fits the following descriptions. a) the Group 13 metal in the third period b) the Group 15 metalloid in the fourth period c) the lightest of the noble gases d) the halogen that exists as a liquid at room temperature e) the only metal that is a liquid at room temperature

A. Al B. As C. He D. Br E. Hg

What is the group number of each of the following families of elements? Write the symbols for the elements in each family. a) alkali metals b) halogens c) alkaline earth metals d) noble gases

A. Group 1: Li, Na, K, Rb, Cs, and Fr B. Group 17: F, Cl, Br, I, and At C. Group 2: Be, Mg, Ca, Sr, Ba, and Ra D. Group 18: He, Ne, Ar, Kr, Xe, and Rn

Classify each of the elements in question 6 as a metal, nonmetal, or metalloid.

A. nonmetal B. nonmetal C. nonmetal D. metal E. metal F. metalloid G. metal H. metal.

Use the periodic table to identify by name and symbol the elements that have the following locations. a) Group 15, Period 3 b) Group 2, Period 6 c) Group 17, Period 2 d) Group 14. Period 5

A. phosphorous, P B. barium, Ba C. fluorine, F D. tin, Sn

Americium (Am) is an actinide that's used in smoke detectors. What property of actinides makes this element useful in a smoke detector?

Americium is radioactive.

Germanium has the same type of structure and semiconducting properties as silicon. What type of semiconductor would you expect arsenic-doped germanium to be?

Arsenic has five valence electrons, and germanium has four. Therefore, arsenicdoped germanium would be an n-type semiconductor.

What can you deduce from the periodic table about the properties of the element barium?

Barium is a metal in Group 2 with two valence electrons in the sixth energy level. It has all the properties of a typical metal.

Which elements among the following have similar chemical properties? a) Be b) Sr c) Cs d) F e) Ar f) I

Be and Sr; F and I

Identify the two elements that are liquids at room temperature and pressure. Explain why one is a metal and the other is a nonmetal.

Bromine and mercury are liquids. Mercury is a metal because it has two valence electrons that are not tightly held. Bromine is a nonmetal because it has seven valence electrons that are tightly held.

What two fields did Primo Levi combine in his life's work?

Chemistry and literature

Explain why electrical conductivity increases in the elements in Group 14 as atomic number increases.

Electrical conductivity increases because the outer-level electrons are farther from the nucleus and can move more freely.

Describe element number 18 in terms of its period and group number, family name, and closest neighboring elements.

Element number 18 is in Period 3 and Group 18. It is a noble gas, and its nearest neighbors are Ne, F, Cl, Br, and Kr.

In the system of numbering groups of elements from 1 to 18 on the periodic table, explain the significance of the group numbers 1, 2, 13, 14, 15, 16, 17, and 18.

Group numbers 1 and 2 are equal to the number of valence electrons. The second digit of group numbers 13, 14, 15, 16, 17, and 18 is equal to the number of valence electrons.

How is the transformation from one crystalline phase to another different from melting or boiling?

Melting and boiling involve a change of state, whereas transformation from one crystalline phase to another occurs in the atom.

Mendeleev said that the properties of the elements repeat periodically when the elements are arranged in a certain way. How did Mendeleev arrange the elements?

Mendeleev arranged the elements according to increasing atomic mass.

Explain how the metallic properties of the elements change as you move across a period from left to right. Why do the properties change in the manner?

Metallic properties decrease from left to right in the periodic table because of increasing numbers of valence electrons.

What are the major differences in the physical properties of metals, nonmetals, and metalloids?

Metals are lustrous, are easily deformed and drawn into wires, and are good conductors of heat and electricity. Nonmetals are not lustrous, may be hard or soft, are usually brittle, and are poor conductors of heat and electricity. Metalloids look Ne Cl P B He like metals but have physical properties that are between those of metals and nonmetals.

Where are metals usually found on the periodic table? Where are nonmetals found? The metalloids?

Metals are on the left side and in the center; nonmetals are in the upper-right corner; metalloids form a border between the metals and nonmetals.

Compare the atomic structure of metal, metalloids, and nonmetals. Explain how atomic structure accounts for differences in electrical conductivity.

Metals have three or fewer valence electrons; metalloids have three to six valence electrons; nonmetals have four to eight valence electrons. Metals are good conductors because their valence electrons are not tightly held and are free to move. Metalloids hold their valence electrons tightly in crystal structures, and the electrons have limited freedom to move. Nonmetals hold their valence electrons tightly, and they are not free to move.

What properties of nickel and zinc make them good substitutes for copper and silver in coins?

Ni and Zn are corrosion resistant, malleable, and relatively abundant.

An incomplete set of atomic mass, density, and melting point data is given for three elements in a triad. Following the patterns of Dobereiner's triads, predict a likely number for each missing value. Element: K, Rb, Cs Atomic Mass (u): 39.1, ?, 133 Density (g/mL): ?, 1.53, 1.87 Melting Point (K): 336, 313, ?

Rb—atomic mass, 86.1u; K—density, 1.19 g/ml; Cs—melting point, 290 K

The noble gases share a unique chemical property. Describe this property and explain why they have it.

The noble gases are unreactive because they have a filled valence level.

How does the arrangement of elements in periods reflect electron structure?

The period number of an element is equal to the number of the energy level that is occupied by the valence electrons.

What is the modern periodic law? How does it differ from Mendeleev's periodic law?

The physical and chemical properties of the elements repeat in a regular pattern when the elements are arranged in order of increasing atomic number. Mendeleev's periodic law stated that the properties repeat when the elements are arranged in order of increasing atomic mass.

The modern periodic law says that the properties of the elements repeat periodically when the elements are arranged according to a certain trend. What is that trend?

The properties of the elements repeat periodically when the elements are arranged according to increasing atomic number.

Which of the Dobereiner triads shown are still listed in the same column of the modern periodic table? Triad 1: Li, Na, K Triad 2: Mn, Cr, Fe Triad 3: S, Se, Te

Triad 1 (Li, Na, and K) and Triad 3 (S, Se, and Te) are still in the same columns.

What are two factors that contributed to the widespread acceptance of Mendeleev's periodic table?

Two factors that led to the widespread acceptance of Mendeleev's table were its ability to predict undiscovered elements and its grouping of elements with similar chemical properties

Use the periodic table to separate these 12 elements into six pairs of elements having similar properties. Ca, K, Ga, P, Si, Rb, B, Sr, Sn, Cl, Bi, Br

You would predict that Ca and Sr, K and Rb, Ga and B, P and Bi, Si and Sn, and Cl and Br would have similar properties.