Periodic Trends Investigation PDF

Preview

Summary

I got a 25/25 on this so it's all correct....

Description

Periodic Properties of the Elements Periodic Trends Investigation

Objectives ● ●

Analyze trends within groups and periods on the periodic table of elements. (Exploration 1) Determine the identity of seven mystery elements based on periodic table trends. (Exploration 2)

Description of Activity In this activity, a partial periodic table is provided. You will select an element and evaluate the element’s physical properties. After fixing,the element, you will analyze the patterns of these properties as they occur across a period and trends that exist down a group. You will identify several mystery elements by investigating and interpreting periodic trends. Remember that valence electrons are the electrons in an atom’s outermost orbitals, which are involved in chemical bonding. Transition metals tend to form more than one cation, and the trend associated with the number of valence electrons is, therefore, less predictable for the transition elements.

Jump Start 1. Dmitri Mendeleev organized the periodic table according to increasing atomic mass. How is the modern periodic table organized? Dmitri Mendeleev’s organization of the periodic table is quite the same. The elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass, and the rows are called periods. 2. Explain the difference between a chemical property and a physical property. A physical property can be observed and measured. Also, it never changes the identity of the substance. Physical properties include color, density, hardness, and melting and boiling points. Unlike physical properties, chemical properties include flammability, corrosion, and oxidation. 3. Define periodicity as it relates to the organization of elements on the periodic table. Periodicity leads to trends or recurring differences in element properties with growing atomic numbers. 4. What defines a group of elements? The thing that defines a group of elements is the valance electron count.

Exploration 1: Looking for Trends Procedure:

Part I In Exploration 1, select the element from period 2, group 1, on the periodic table. When selected, the group and the period number will be highlighted by red circles. Select the element’s period (row) number, represented by a red circle. Record the element’s properties from the list provided in part 1 of Table 1. Note that you can select various periodic trends for the element and period. These trends appear as graphs on the right side of the screen. Observe the graph for the atomic radius (pm). Describe the relationship between nuclear radius and atomic number for all the elements in period 2, and record these observations in part 1 of Table 2 in the row labeled Trends Across Period 2. Select Atomic mass (AMU). Observe the graph, and evaluate the trend for atomic mass as a function of increasing atomic number. Record your observations in Table 2 in the row labeled Trends Across Period 2. Similarly, evaluate the trends for the number of valence electrons of the main group elements, electronegativity, density (g/cm3), and melting point (°C) as a function of increasing atomic number for period 2. Record observations for each trend in Table 2 in the row labeled Trends Across Period 2. When finished, select Close to return to the periodic table. Repeat steps 1–7 for the group 1 element in periods 3, 4, and 5, respectively. Record each element’s properties in part 1 of Table 1 and each period’s trends in the appropriate row of part I, Table 2. Part II Select the element that resides in period 2, group 1. Choose the element’s group (column) number, represented by a red circle. Record the element’s properties in part 2 of Table 1. Select the graph buttons, and observe the graph trends for the atomic radius (pm), nuclear mass (AMU), number of valence electrons, electronegativity, density (g/cm3), and melting point (°C). Record these trends in part 2 of Table 2 in the row labeled Trends Down Group 1. Repeat steps 9–11 for the period 2 elements in groups 2, 13, 14, 15, 16, 17, and 18. (There are no transition elements in period 2, so there is a gap in the group numbering between 2 and 13.) Observations and Analysis Table 1 Part 1:

Symbol

Period

Atomic

Atomic

Atomic

Density

Electro-ne

Melting

Valence

Number

Mass

Radius

(g/cm3)

gativity

Point (°C)

Electrons

(AMU)

(pm)

Number

2

Li

3

6.941

152

0.535

1

180.54

1

3

Na

11

22.99

186

0.968

0.9

97.72

1

4

K

19

39.098

227

0.856

0.8

63.38

1

5

Rb

37

85.468

248

1.532

0.8

39.31

1

Part 2:

Symbol

Group

Atomic

Atomic

Atomic

Density

Electro-ne

Melting

Valence

Number

Mass

Radius

(g/cm3)

gativity

Point (°C)

Electrons

(AMU)

(pm)

Number

1

Li

3

6.941

152

0.535

1

180.54

1

2

Be

4

9.012

112

1.848

1.6

1287

2

13

B

5

10.811

85

2.46

2

2076

3

14

C

6

12.011

77

2.267

2.6

3527

4

15

N

7

14.007

75

0.001241

3

-210

5

16

O

8

15.999

73

0.001429

3.4

-218.3

6

17

F

9

18.998

71

0.001251

4

-219.62

7

18

Ne

10

20.18

71

0.000899

0

-248.59

8

Table 2 Part 1

Atomic Radius (pm)

Atomic Mass (AMU)

Number of Valence Electrons

Electro-negativi ty

Density 3

(g/cm )

Melting Point (°C)

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Across

number

number

number

number

number

number

Period 2

increases, the

increases, the

increases, the

increases, the

increases,

increases, the

Atomic radius

atomic mass

number of

electronegativity

the density

melting point

decreases.

increases.

valance

increases until

has a large

spikes but

electrons

the graph ends.

hill in the

flattens at the

increases.

Once it hits the

graph and

atomic number

end, it rapidly

flattens out

7.

decreases.

the atomic number 7.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Across

number

number

number

number

number

number

Period 3

increases, the

increases, the

increases, the

increases, the

increases,

increases, the

Atomic radius

atomic mass

number of

electronegativity

the density

melting point

decreases.

increases.

valance

increases until

has a large

spikes but

electrons

the graph ends.

hill in the

slowly

increases.

Once it hits the

graph and

decreases at

end, it rapidly

flattens out at

the atomic

decreases.

the atomic

number 16.

number 17.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Across

number

number

number

number

number

number

Period 4

increases, the

increases, the

increases, the

increases,

increases,

increases, the

Atomic radius

Atomic radius

number of

eases, the

the density

melting point

rapidly

rapidly jumps

valance

electronegativity

spikes on the

spikes up and

decreases but

up but then

electrons

increases until

graph but

down but

slowly

slowly

increases.

the graph ends.

then rapidly

rapidly

decreases at

increases at

Once it hits the

decreases.

decreases at

the atomic

the atomic

end, it rapidly

the atomic

number 32.

number 31.

decreases.

number 33.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Across

number

number

number

number

number

number

Period 5

increases, the

increases, the

increases, the

increases, the

increases,

increases, the

Atomic radius

Atomic radius

number of

electronegativity

the density

melting point

decreases.

rapidly jumps

valance

increases until

spikes on the

spikes up and

up but slowly

the graph ends.

graph but

down.

increases at

Once it hits the

the atomic

electrons

end, it rapidly

then rapidly

number 49.

increases.

decreases.

decreases.

Part 2

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Down

number

number

number

number

number

number

Group 1

increases, the

increases, the

increases, the

increases, the

increases,

increases, the

Atomic radius

Atomic radius

number of

electronegativity

the density

melting point

decreases.

increases.

valance

decreases.

increases.

decreases.

electrons stays the same.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Down

number

number

number

number

number

number

Group 2

increases, the

increases, the

increases, the

increases, the

increases,

increases, the

Atomic radius

Atomic radius

number of

electronegativity

the density

melting point

increases.

increases.

valance

decreases.

decreases

decreases

electrons stays

then rapidly

rapidly and

the same.

increases.

increases barely.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Down

number

number

number

number

number

number

Group 13

increases, the

increases, the

increases, the

increase,s the

increases,

increases, the

Atomic radius

Atomic radius

number of

electronegativity

the density

melting point

increases.

increases.

valance

spikes down,

decreases

decreases.

electrons stays

then up, it

then rapidly

the same.

flattens out.

increases.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Down

number

number

number

number

number

number

Group 14

increases, the

increases, the

increases, the

increases the

increases the

increases the

Atomic radius

Atomic radius

number of

electronegativity

density

melting point

increases.

increases.

valance

decreases

increases.

decreases.

electrons stays

rapidly but then

the same.

flattens out.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Down

number

number

number

number

number

number

Group 15

increases, the

increases, the

increases, the

increases, the

increases,

increases, the

Atomic radius

Atomic radius

number of

electronegativity

the density

melting point

increases.

increases.

valance

decreases

increases.

increases

electrons stays

rapidly but then

rapidly but then

the same.

flattens out.

decreases only a little.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Down

number

number

number

number

number

number

Group 16

increases, the

increases, the

increases, the

increases, the

increases,

increases, the

Atomic radius

Atomic radius

number of

electronegativity

the density

melting point

increases.

increases.

valance

decreases.

increases.

increases.

electrons stays the same.

Trends

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

As the atomic

Down

number

number

number

number

number

number

Group 17

increases, the

increases, the

increases, the

increases, the

increases,

increases, the

Atomic radius

Atomic radius

number of

electronegativity

the density

melting point

increases.

increases.

valance

decreases.

increases.

increases.

electrons stays the same.

Trends

As the atomic

As the atomic

As the atomic

(The

As the atomic

As the atomic

Down

number

number

number

electronegativity

number

number

Group 18

increases, the

increases, the

increases, the

button does not

increases,

increases, the

Atomic radius

Atomic radius

number of

work on this

the density

melting point

increases.

increases.

valance

one.) I assume

increases.

increases.

electrons stays

that as the

the same.

atomic number increases, the electronegativity decreases.

1. What is the trend in the number of valence electrons as you move down a group? Across a period? The trend I saw was that the number of valance electrons stays the same when going across a period, but when I looked at going down a group, I saw that the number of valance electrons increases as the atomic number increases. 2. Interpret the general electronegativity trend that exists for elements across the same period. Explain why this trend occurs. As I went across the same period, I saw the general electronegativity as the atomic number increases and the electronegativity decreases. This would make sense because you move from the far right to the far left as you increase the atomic number. That would explain the sudden spikes going from the atomic number 10 to 11. 3. Analyze the trend in atomic radius for elements located within the same group on the periodic table. Explain this trend. As you move down the group, the radius grows. This is due to the nucleus being sma...