Question

1. when

ucleus{84}{218}po emits a beta particle, it transforms into a new element.
a. write out the nuclear equation:
_____________________________
b. fill out the chart below:

	name of the element	atomic number	atomic mass	# of protons	# of electrons	# of neutrons
parent element
daughter element

1. in a paper - making factory, beta radiation is used to check that the paper being produced is the correct thickness. if the paper gets too thin, the reading on the detector increases causing the rollers to move apart to make the paper thicker. if the paper gets too thick, the reading on the detector goes down causing the rollers to move closer together. a diagram of this set - up is shown below:

diagram of paper - making factory setup with rollers, paper, detector, and β source
explain why beta radiation is used for this procedure rather than alpha or gamma radiation.

Explanation:

7a. Explanation:

Step1: Recall Beta Decay Rules

In beta decay ($\beta^-$), a neutron converts to a proton, so atomic number ($Z$) increases by 1, mass number ($A$) remains same. For $\ce{_{84}^{218}Po}$, $Z = 84$, $A = 218$. The beta particle is $\ce{_{-1}^0 e}$.

Step2: Write Nuclear Equation

Parent: $\ce{_{84}^{218}Po}$, daughter: $Z = 84 + 1 = 85$ (Astatine, At), $A = 218$. So equation: $\ce{_{84}^{218}Po
ightarrow _{85}^{218}At + _{-1}^0 e}$

7a. Answer:

$\boldsymbol{\ce{_{84}^{218}Po
ightarrow _{85}^{218}At + _{-1}^0 e}}$

7b. Explanation:

Step1: Parent Element (Polonium)

• Name: Polonium (Po)
• Atomic Number ($Z$): 84 (protons = 84, electrons = 84 in neutral atom)
• Atomic Mass ($A$): 218
• Neutrons: $A - Z = 218 - 84 = 134$

Step2: Daughter Element (Astatine)

• Name: Astatine (At)
• Atomic Number: 85 (protons = 85, electrons = 85)
• Atomic Mass: 218 (mass number unchanged in beta decay)
• Neutrons: $218 - 85 = 133$

7b. Answer:

	Name of the Element	Atomic Number	Atomic Mass	# Of Protons	# Of Electrons	# Of Neutrons
Daughter Element	Astatine	85	218	85	85	133

8. Explanation:

Step1: Analyze Alpha Radiation

Alpha particles are large (2 protons, 2 neutrons), highly ionizing, and have low penetration (stopped by paper). So alpha can't pass through paper, can't detect thickness changes.

Step2: Analyze Gamma Radiation

Gamma rays are high-energy photons, very penetrating (pass through thick paper easily). Thickness changes (thin/thick) would have little effect on gamma detection, so can't sense thickness.

Step3: Analyze Beta Radiation

Beta particles (electrons) have moderate penetration: pass through thin paper, but absorbed/attenuated by thicker paper. So paper thickness changes (thin → more beta reaches detector; thick → less beta reaches detector), allowing detection and adjustment.

8. Answer:

Beta radiation is used because:

• Alpha radiation has low penetration (stopped by paper), so it cannot pass through to be detected, making it useless for measuring paper thickness.
• Gamma radiation has very high penetration (passes through most thicknesses of paper), so changes in paper thickness would barely affect the detector reading, making it ineffective.
• Beta radiation has moderate penetration: it can pass through thin paper (more radiation reaches the detector) but is absorbed/attenuated by thicker paper (less radiation reaches the detector). This allows the detector to sense changes in paper thickness, triggering the roller adjustment.

Answer:

7a. Explanation:

Step1: Recall Beta Decay Rules

In beta decay ($\beta^-$), a neutron converts to a proton, so atomic number ($Z$) increases by 1, mass number ($A$) remains same. For $\ce{_{84}^{218}Po}$, $Z = 84$, $A = 218$. The beta particle is $\ce{_{-1}^0 e}$.

Step2: Write Nuclear Equation

Parent: $\ce{_{84}^{218}Po}$, daughter: $Z = 84 + 1 = 85$ (Astatine, At), $A = 218$. So equation: $\ce{_{84}^{218}Po
ightarrow _{85}^{218}At + _{-1}^0 e}$

7a. Answer:

$\boldsymbol{\ce{_{84}^{218}Po
ightarrow _{85}^{218}At + _{-1}^0 e}}$

7b. Explanation:

Step1: Parent Element (Polonium)

• Name: Polonium (Po)
• Atomic Number ($Z$): 84 (protons = 84, electrons = 84 in neutral atom)
• Atomic Mass ($A$): 218
• Neutrons: $A - Z = 218 - 84 = 134$

Step2: Daughter Element (Astatine)

• Name: Astatine (At)
• Atomic Number: 85 (protons = 85, electrons = 85)
• Atomic Mass: 218 (mass number unchanged in beta decay)
• Neutrons: $218 - 85 = 133$

7b. Answer:

	Name of the Element	Atomic Number	Atomic Mass	# Of Protons	# Of Electrons	# Of Neutrons
Daughter Element	Astatine	85	218	85	85	133

8. Explanation:

Step1: Analyze Alpha Radiation

Alpha particles are large (2 protons, 2 neutrons), highly ionizing, and have low penetration (stopped by paper). So alpha can't pass through paper, can't detect thickness changes.

Step2: Analyze Gamma Radiation

Gamma rays are high-energy photons, very penetrating (pass through thick paper easily). Thickness changes (thin/thick) would have little effect on gamma detection, so can't sense thickness.

Step3: Analyze Beta Radiation

Beta particles (electrons) have moderate penetration: pass through thin paper, but absorbed/attenuated by thicker paper. So paper thickness changes (thin → more beta reaches detector; thick → less beta reaches detector), allowing detection and adjustment.

8. Answer:

Beta radiation is used because:

• Alpha radiation has low penetration (stopped by paper), so it cannot pass through to be detected, making it useless for measuring paper thickness.
• Gamma radiation has very high penetration (passes through most thicknesses of paper), so changes in paper thickness would barely affect the detector reading, making it ineffective.
• Beta radiation has moderate penetration: it can pass through thin paper (more radiation reaches the detector) but is absorbed/attenuated by thicker paper (less radiation reaches the detector). This allows the detector to sense changes in paper thickness, triggering the roller adjustment.