Question

periodic trends: straw lab

aluminum al 13 0.143
silicon si 14 0.117
phosphorus p 15 0.110
sulfur s 16 0.104

to calculate the scale factor:
measure the length of a precut straw = ______ cm
divide the length of the straw by 2 = ______ cm
divide that number by 0.186 = scale factor ______ cm

to calculate the length of your straw:
multiply the scale factor by the size of radius given in your data table. answer the following
questions in your lab notebook:

1. in a sentence, describe the relationship between atomic number and the size of the atom’s

radius going down a group on the periodic table.

1. why does this relationship make sense in relation to what you know about elements on the

periodic table?

1. in a sentence, describe the relationship between atomic number and the size of each atom’s

radius when going across a period on the periodic table. 4) why does this trend make sense in
relation to what you know about the attraction between subatomic particles within the atom?

ionization energy:
the ionization energy for the following elements is estimated to have the following values:

name	symbol	atomic number	ionization energy (kj/mol)	calculated straw length (cm)
magnesium			736
calcium			590
lithium			519
boron			799
carbon			1088
nitrogen			1406

Explanation:

Since the problem involves understanding periodic trends (atomic radius, ionization energy) and performing calculations related to a lab activity on these concepts, the relevant subfield under Natural Science is Chemistry (specifically, Inorganic Chemistry or Periodic Chemistry, focusing on periodic trends).

Let's tackle a part of the calculation (assuming we measure the precut straw length, say, as an example: let's assume the precut straw length is 10 cm for demonstration; in a real lab, you'd measure it):

Step 1: Measure the length of a precut straw

Let’s assume the measured length of the precut straw is \( 10 \) cm (you would use the actual measured value in the lab).
Expression: \( \text{Straw length} = 10 \) cm

Step 2: Divide the length of the straw by 2

\( \frac{10}{2} = 5 \) cm
Expression: \( \frac{\text{Straw length}}{2} = \frac{10}{2} = 5 \) cm

Step 3: Divide that number by 0.186 to get the scale factor

\( \frac{5}{0.186} \approx 26.88 \) cm (this is the scale factor; the actual value depends on your measured straw length)
Expression: \( \text{Scale factor} = \frac{\frac{\text{Straw length}}{2}}{0.186} = \frac{5}{0.186} \approx 26.88 \) cm

Step 4: Calculate the length of the straw for an element (e.g., Aluminum with radius 0.143 nm)

Multiply the scale factor by the atomic radius (note: the radius units here are likely in nanometers, but the scale factor is in cm; assuming the radius is given in a unit compatible with the scale factor calculation, or there’s a unit conversion—for simplicity, using the given radius value as is):
\( \text{Straw length for Al} = \text{Scale factor} \times \text{Atomic radius} = 26.88 \times 0.143 \approx 3.84 \) cm
Expression: \( \text{Straw length} = \text{Scale factor} \times \text{Atomic radius} \)

For the conceptual questions (e.g., relationship between atomic number and atomic radius across a period):

1. Relationship across a period: As the atomic number increases across a period (from left to right), the atomic radius generally decreases. This is because the number of protons (positive charge) in the nucleus increases, pulling the electron cloud (negative charge) closer to the nucleus, even though the number of electron shells remains the same.

1. Why it makes sense: Elements in the same period have the same number of electron shells. As atomic number (protons) increases, the nuclear charge increases, which exerts a stronger pull on the valence electrons, reducing the atomic radius.

Final Answer (for the calculation example, using the assumed straw length):

• Scale factor (with straw length = 10 cm): \( \approx 26.88 \) cm
• Straw length for Aluminum (radius = 0.143): \( \approx 3.84 \) cm

(Note: Actual values depend on the measured straw length in the lab.)

Answer:

Since the problem involves understanding periodic trends (atomic radius, ionization energy) and performing calculations related to a lab activity on these concepts, the relevant subfield under Natural Science is Chemistry (specifically, Inorganic Chemistry or Periodic Chemistry, focusing on periodic trends).

Let's tackle a part of the calculation (assuming we measure the precut straw length, say, as an example: let's assume the precut straw length is 10 cm for demonstration; in a real lab, you'd measure it):

Step 1: Measure the length of a precut straw

Let’s assume the measured length of the precut straw is \( 10 \) cm (you would use the actual measured value in the lab).
Expression: \( \text{Straw length} = 10 \) cm

Step 2: Divide the length of the straw by 2

\( \frac{10}{2} = 5 \) cm
Expression: \( \frac{\text{Straw length}}{2} = \frac{10}{2} = 5 \) cm

Step 3: Divide that number by 0.186 to get the scale factor

\( \frac{5}{0.186} \approx 26.88 \) cm (this is the scale factor; the actual value depends on your measured straw length)
Expression: \( \text{Scale factor} = \frac{\frac{\text{Straw length}}{2}}{0.186} = \frac{5}{0.186} \approx 26.88 \) cm

Step 4: Calculate the length of the straw for an element (e.g., Aluminum with radius 0.143 nm)

Multiply the scale factor by the atomic radius (note: the radius units here are likely in nanometers, but the scale factor is in cm; assuming the radius is given in a unit compatible with the scale factor calculation, or there’s a unit conversion—for simplicity, using the given radius value as is):
\( \text{Straw length for Al} = \text{Scale factor} \times \text{Atomic radius} = 26.88 \times 0.143 \approx 3.84 \) cm
Expression: \( \text{Straw length} = \text{Scale factor} \times \text{Atomic radius} \)

For the conceptual questions (e.g., relationship between atomic number and atomic radius across a period):

1. Relationship across a period: As the atomic number increases across a period (from left to right), the atomic radius generally decreases. This is because the number of protons (positive charge) in the nucleus increases, pulling the electron cloud (negative charge) closer to the nucleus, even though the number of electron shells remains the same.

1. Why it makes sense: Elements in the same period have the same number of electron shells. As atomic number (protons) increases, the nuclear charge increases, which exerts a stronger pull on the valence electrons, reducing the atomic radius.

Final Answer (for the calculation example, using the assumed straw length):

• Scale factor (with straw length = 10 cm): \( \approx 26.88 \) cm
• Straw length for Aluminum (radius = 0.143): \( \approx 3.84 \) cm

(Note: Actual values depend on the measured straw length in the lab.)