HW From textbook “CHEMISTRY a Contemporary Approach”

Do Exercises 5.1, 5.2, 5.3 p173&174

Do Questions 9,10,16,21,22,28 p179-181

The succession of elements within the same group and period demonstrates characteristic trends. See table S

Atomic radius trend

• In groups, atomic radii increase with atomic number because the number of energy level increases.

  Problem

  Verify the trend  by making a bar graph for group 1.

   

• In periods, atomic radii decrease when atomic number increases because the nuclear charges increase attracting electrons closer to the nucleus.

  Problem

  Verify the trend  by making a line graph for period 2.

Ionic radius trend

            Cations (positive ions) are always smaller than their parent atoms and anions (negative ions) are always larger.

            Example

            When compare to the neutral atom of  S, the ion S^-2 has a larger radius than S while S⁺⁴ and S⁺⁵ are respectively smaller.

Electronegativity trend

• In groups, electronegativity decreases when atomic number increases because the added energy levels shield the power of the nucleus to attract electrons.

  Problem

  Verify the trend  by making a bar graph for group 2.

   

• In periods, electronegativity increases with atomic number because the increase in nuclear charge makes the nucleus more powerful to hold on to electrons.

  Problem

  Verify the trend  by making a line graph for period 3.

First ionization energy trend

• In groups,  ionization energy decreases when atomic number increases because the added energy levels shield the power of the nuclear charge making it easier to remove outmost electrons.

  Problem

  Verify the trend  by making a bar graph for group 17.

   

• In periods,  ionization energy increase with atomic number because the increase in nuclear charge makes it more difficult to remove outmost electrons.

  Problem

  Verify the trend  by making a line graph for period 2.

Metallic properties trend

All elements possess from very low to very high metallic character.  Fr has the most metallic character and F has the least.

• In groups,  metallic character increases with atomic number because each successive element gets closest to Fr.

   

• In periods,  metallic character decreases when atomic number increases because each successive element gets closest to F.

Metals reactivity trend

• In groups, reactivity of metals increases with atomic number because the ionization energy decreases.

Note: Very reactive metals such as Li and Na are obtained from their fused salts under electrolysis.

Example

LiCl and NaBr

• In periods, reactivity of metals decreases when atomic number increases because the ionization energy increases.

Nonmetals reactivity trend

• In groups, reactivity of non-metals decreases when atomic number increases because the electronegativity decreases.

Note: Very reactive nonmetals such as F and Cl are obtained from their fused salts under electrolysis.

Example

LiF and NaF

• In periods, reactivity of non-metals  increases with atomic number because the electronegativity increases.

TEST YOUR UNDERSTANDING

6/07

5 Which two characteristics are associated with metals?

(1) low first ionization energy and low electronegativity  (2) low first ionization energy and high electronegativity

(3) high first ionization energy and low electronegativity (4) high first ionization energy and high electronegativity

32 Which grouping of circles, when considered in order from the top to the bottom, best represents the relative size of the atoms of Li, Na, K, and Rb, respectively?

8/07

14 An ion of which element has a larger radius than an atom of the same element? (1) aluminum (2) chlorine (3) magnesium (4) sodium

34 How do the atomic radius and metallic properties of sodium compare to the atomic radius and metallic properties of phosphorus?

(1) Sodium has a larger atomic radius and is more metallic. (2) Sodium has a larger atomic radius and is less metallic.

(3) Sodium has a smaller atomic radius and is more metallic. (4) Sodium has a smaller atomic radius and is less metallic.

1/06

6/06

8/06

1/05

33 As the elements in Group 17 on the Periodic Table are considered from top to bottom, what happens to the atomic radius and the metallic character of each successive element?

                (1) The atomic radius and the metallic character both increase.

                (2) The atomic radius increases and the metallic character decreases.

                (3) The atomic radius decreases and the metallic character increases.

                (4) The atomic radius and the metallic character both decrease.

6/05

35 The data table below shows elements Xx, Yy, and Zz from the same group on the Periodic Table.

What is the most likely atomic radius of element Yy? (1) 103 pm          (2) 127 pm            (3) 166 pm            (4) 185 pm

1/04

8 The amount of energy required to remove the outermost electron from a gaseous atom in the ground state is known as
        (1) first ionization energy (2) activation energy (3) conductivity (4) electronegativity

34 As the atoms of the Group 17 elements in the ground state are considered from top to bottom,
each successive element has
        (1) the same number of valence electrons and similar chemical properties

        (2) the same number of valence electrons and identical chemical properties
        (3) an increasing number of valence electrons and similar chemical properties
        (4) an increasing number of valence electrons and identical chemical properties

49 As each successive element in Group 15 of the Periodic Table is considered in order of increasing atomic number, the atomic radius
        (1) decreases (2) increases (3) remains the same

6/04

50 As the elements of Group 1 on the Periodic Table are considered in order of increasing atomic radius, the ionization energy of each successive element generally (1) decreases (2) increases (3) remains the same

8/03

38 As the elements in Period 2 of the Periodic Table are considered in succession from left to right, there is a decrease in atomic radius with increasing atomic number. This may best be explained by the fact that the
        (1) number of protons increases, and the number of shells of electrons remains the same

        (2) number of protons increases, and the number of shells of electrons increases
        (3) number of protons decreases, and the number of shells of electrons remains the same
        (4) number of protons decreases, and the number of shells of electrons increases

Base your answers to questions 56 through 58 on the Reference Tables for Physical Setting/ Chemistry.
56 Complete the data table provided below for the following Group 18 elements: He, Ne, Ar, Kr, Xe

57 Using information from your data table in question 56, construct a line graph following the directions below. Circle each point and connect the points.

58 Based on your graph in question 57, describe the trend in first ionization energy of Group 18 elements as the atomic number increases.

6/02

1 Base your answers on the table below which shows the electronegativity of selected elements of Period 2 of the Periodic Table.

a) On the grid provided in your answer booklet, set up a scale for electronegativity on the y-axis. Plot the data by drawing a best-fit line.  

b) Using the graph, predict the electronegativity of nitrogen.

c) For these elements, state the trend in electronegativity in terms of atomic number. 

2 Which of the following Group 15 elements has the greatest metallic character? (1) nitrogen (2) phosphorus  (3) antimony (4) bismuth

3 What are two properties of most nonmetals?

        (1) high ionization energy and poor electrical conductivity (2) high ionization energy and good electrical conductivity

        (3) low ionization energy and poor electrical conductivity (4) low ionization energy and good electrical conductivity

4 Compared to the radius of a chlorine atom, the radius of a chloride ion is

        (1) larger because chlorine loses an electron (2) larger because chlorine gains an electron

        (3) smaller because chlorine loses an electron (4) smaller because chlorine gains an electron

8/02

1 One electron is removed from both a Na atom and a K atom, producing two ions. Using principles of atomic structure, explain why the Na ion is much smaller than the K ion. Discuss both ions in your answer.  

2 Which of the following Group 2 elements has the lowest ionization energy?  (1) Be  (2) Mg (3) Ca  (4) Ba

3 Compared to the nonmetals in Period 2, the metals in Period 2 generally have larger

            (1) ionization energies   (2) electronegativities                (3) atomic radii             (4) atomic numbers

4 As the elements in Group 17 are considered in order of increasing atomic number, the chemical reactivity of each successive element

            (1) decreases    (2) increases     (3) remains the same

5  In Period 3, from left to right in order, each successive element will

            (1) decrease in electronegativity   (2) decrease in atomic mass (3) increase in number of protons          (4) increase in metallic character

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