Q1. Write the symbolic notation for atoms with:

• a. 5 protons and 6 neutrons.

• b. 35 protons and 46 neutrons.

Background

Topic: Atomic Number, Mass Number, and Symbolic Notation

This question tests your understanding of how to represent atoms using symbolic notation, based on their number of protons and neutrons.

Key Terms and Formulas

• Atomic Number (Z): Number of protons in the atom.

• Mass Number (A): Number of protons plus neutrons.

• Symbolic Notation: where is the element symbol, is the mass number, and is the atomic number.

Step-by-Step Guidance

1. For each atom, identify the atomic number () as the number of protons.

2. Calculate the mass number () by adding the number of protons and neutrons: .

3. Find the element symbol () using the periodic table for the atomic number.

4. Write the symbolic notation in the form for each atom.

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Q2. Determine the number of protons, neutrons, and electrons for each of the following atoms:

• a.

• b.

• c.

Background

Topic: Subatomic Particles in Atoms

This question tests your ability to interpret symbolic notation and determine the number of protons, neutrons, and electrons in an atom.

Key Terms and Formulas

• Protons: Equal to atomic number ().

• Neutrons: (mass number minus atomic number).

• Electrons: For a neutral atom, electrons = protons.

Step-by-Step Guidance

1. For each atom, identify the atomic number () and mass number () from the symbolic notation.

2. Calculate the number of protons ().

3. Calculate the number of neutrons: .

4. For neutral atoms, set the number of electrons equal to the number of protons.

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Q3. There are three naturally occurring isotopes of magnesium: magnesium-24, magnesium-25, and magnesium-26.

• a. How many neutrons are present in each isotope?

• b. Write complete symbolic notation for each isotope.

• c. Based on the average atomic mass given in the periodic table, which isotope of magnesium is the most abundant?

Background

Topic: Isotopes and Atomic Mass

This question tests your understanding of isotopes, symbolic notation, and how atomic mass relates to isotope abundance.

Key Terms and Formulas

• Isotope: Atoms of the same element with different numbers of neutrons.

• Symbolic Notation: (Magnesium has atomic number 12).

• Neutrons: .

Step-by-Step Guidance

1. For each isotope, use the mass number () and atomic number ( for Mg) to calculate neutrons: .

2. Write the symbolic notation for each isotope: .

3. Compare the mass numbers to the average atomic mass of magnesium (from the periodic table) to predict the most abundant isotope.

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Q4. ALLIED HEALTH: A routine dental exam often includes four bite-wing X-rays, exposing a patient to a total of 5 mrem of radiation. Would this cause radiation sickness in the patient? If so, what would be the effects?

Background

Topic: Biological Effects of Radiation

This question tests your understanding of radiation units (mrem) and the clinical effects of exposure.

Key Terms and Formulas

• mrem: Millirem, a unit of radiation dose.

• Radiation Sickness: Clinical effects depend on dose (see table of effects).

Step-by-Step Guidance

1. Identify the total radiation dose received (5 mrem).

2. Compare this dose to the threshold values for clinical effects (e.g., temporary decrease in white blood cells, mild radiation sickness, etc.).

3. Determine if the dose is high enough to cause any detectable effects.

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Q5. Write a balanced nuclear equation for the decay of each of the following:

• a. carbon-14 undergoing beta decay

• b. polonium-212 undergoing alpha decay

Background

Topic: Nuclear Equations and Radioactive Decay

This question tests your ability to write balanced nuclear equations for radioactive decay processes.

Key Terms and Formulas

• Beta Decay:

• Alpha Decay:

Step-by-Step Guidance

1. For each decay, write the symbolic notation for the starting isotope.

2. Apply the rules for beta or alpha decay to determine the products.

3. Balance the mass number and atomic number on both sides of the equation.

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Q6. ALLIED HEALTH: A brain scan uses the radioisotope oxygen-15. The recommended dosage is 50 mCi. A supply of 250 mCi in 20 mL arrives at the lab. How many milliliters will be injected into a patient?

Background

Topic: Radiation Units and Dosage Calculations

This question tests your ability to perform dosage calculations using radioactivity units (mCi) and volume.

Key Terms and Formulas

• mCi: Millicurie, a unit of radioactivity.

• Dosage Calculation: Use ratio and proportion to determine volume needed for a specific activity.

Step-by-Step Guidance

1. Set up a proportion using the supplied activity and volume: .

2. Determine the volume needed for 50 mCi: .

3. Solve for using cross-multiplication.

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Q7. ALLIED HEALTH: Radioactive indium-111 has an effective half-life of 2.5 days. If a dose with an activity of 3.0 mCi is injected in a patient to detect blood clots, how much of the will be active 10 days after the injection is given?

Background

Topic: Half-Life Calculations

This question tests your ability to use the half-life formula to determine the remaining activity of a radioisotope after a given time.

Key Terms and Formulas

• Half-Life (): Time for half the atoms to decay.

• Remaining Activity Formula: where is the number of half-lives elapsed.

Step-by-Step Guidance

1. Calculate the number of half-lives: .

2. Use the formula for remaining activity: .

3. Perform the exponentiation and multiplication to find the remaining activity.

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Q8. ALLIED HEALTH: Chromium-51 is used in imaging red blood cells and has an effective half-life of 27 days. If a dose with an activity of 40 μCi is given to a patient, how long will it take for the patient to have less than 5 μCi present?

Background

Topic: Half-Life and Radioactive Decay

This question tests your ability to determine the time required for a radioactive sample to decay below a certain activity threshold.

Key Terms and Formulas

• Half-Life (): 27 days for chromium-51.

• Decay Formula:

• Threshold: Find such that remaining activity .

Step-by-Step Guidance

1. Set up the inequality: .

2. Solve for using logarithms.

3. Multiply by the half-life (27 days) to find the total time required.

Try solving on your own before revealing the answer!