Nucleus

General physics

Atomic and Nuclear Structure — Physics Lesson

🎯 Learning Objectives

Learning Objectives

Distinguish between nucleon number and proton number
Understand that isotopes are forms of the same element with different numbers of neutrons in their nuclei
Understand and use the notation ^A_ZX for the representation of nuclides
Understand that nucleon number and charge are conserved in nuclear processes
Apply conservation laws to balance nuclear equations
Calculate the number of neutrons in different isotopes

🗣️ Language Objectives

Language Objectives

Use scientific terminology related to atomic and nuclear structure accurately
Distinguish between similar terms (nucleon vs proton number, isotope vs nuclide)
Explain nuclear notation using precise mathematical language
Describe conservation principles in nuclear processes clearly
Communicate atomic structure concepts using appropriate scientific discourse

📝 Key Terms

Key Terms

English Term	Russian Translation	Kazakh Translation
Nucleon Number (A)	Массовое число	Нуклон саны
Proton Number (Z)	Атомный номер	Протон саны
Neutron Number (N)	Число нейтронов	Нейтрон саны
Isotope	Изотоп	Изотоп
Nuclide	Нуклид	Нуклид
Nuclear Notation	Ядерная нотация	Ядролық белгілеу
Conservation Law	Закон сохранения	Сақталу заңы
Nuclear Process	Ядерный процесс	Ядролық процесс

🃏 Topic Flashcards

Interactive Flashcards

Practice with these flashcards to memorize key concepts about atomic and nuclear structure.

📚 Glossary

Glossary

Nucleon Number (A): The total number of protons and neutrons in an atomic nucleus. Also called the mass number because it approximates the atomic mass in atomic mass units.
Translation
Russian: Массовое число — общее количество протонов и нейтронов в атомном ядре. Также называется массовым числом, поскольку приближенно равно атомной массе в атомных единицах массы.
Kazakh: Нуклон саны — атом ядросындағы протондар мен нейтрондардың жалпы саны. Атомдық масса бірліктерінде атомдық массаға жуық болғандықтан масса саны деп те аталады.
Proton Number (Z): The number of protons in an atomic nucleus. This determines the element’s identity and its position in the periodic table. Also called the atomic number.
Translation
Russian: Атомный номер — количество протонов в атомном ядре. Это определяет идентичность элемента и его положение в периодической таблице. Также называется зарядовым числом.
Kazakh: Протон саны — атом ядросындағы протондардың саны. Бұл элементтің дербестігін және оның периодтық кестедегі орнын анықтайды. Атомдық нөмір деп те аталады.
Neutron Number (N): The number of neutrons in an atomic nucleus. Calculated as N = A — Z, where A is the nucleon number and Z is the proton number.
Translation
Russian: Число нейтронов — количество нейтронов в атомном ядре. Вычисляется как N = A — Z, где A — массовое число, а Z — атомный номер.
Kazakh: Нейтрон саны — атом ядросындағы нейтрондардың саны. N = A — Z формуласымен есептеледі, мұнда A — нуклон саны, ал Z — протон саны.
Isotope: Atoms of the same element (same proton number) that have different numbers of neutrons, and therefore different nucleon numbers.
Translation
Russian: Изотопы — атомы одного и того же элемента (одинаковое число протонов), которые имеют разное количество нейтронов и, следовательно, разные массовые числа.
Kazakh: Изотоптар — бірдей элементтің атомдары (бірдей протон саны), бірақ әртүрлі нейтрон санына ие, сондықтан әртүрлі нуклон санына ие.
Nuclide: A specific nucleus characterized by its nucleon number (A) and proton number (Z). Each nuclide has a unique combination of protons and neutrons.
Translation
Russian: Нуклид — конкретное ядро, характеризующееся своим массовым числом (A) и атомным номером (Z). Каждый нуклид имеет уникальную комбинацию протонов и нейтронов.
Kazakh: Нуклид — нуклон саны (A) және протон саны (Z) арқылы сипатталатын нақты ядро. Әрбір нуклид протондар мен нейтрондардың бірегей комбинациясына ие.
Nuclear Notation: The standard way of representing nuclides using the format ^A_ZX, where A is the nucleon number, Z is the proton number, and X is the chemical symbol.
Translation
Russian: Ядерная нотация — стандартный способ представления нуклидов в формате ^A_ZX, где A — массовое число, Z — атомный номер, а X — химический символ.
Kazakh: Ядролық белгілеу — нуклидтерді ^A_ZX форматында көрсетудің стандартты тәсілі, мұнда A — нуклон саны, Z — протон саны, ал X — химиялық символ.
Conservation Laws: Fundamental principles stating that certain quantities (like nucleon number and charge) remain constant before and after nuclear processes.
Translation
Russian: Законы сохранения — фундаментальные принципы, утверждающие, что определенные величины (например, массовое число и заряд) остаются постоянными до и после ядерных процессов.
Kazakh: Сақталу заңдары — белгілі шамалардың (нуклон саны мен заряд сияқты) ядролық процестерге дейін және кейін тұрақты болып қалатынын айтатын іргелі принциптер.

📖 Theory: Atomic and Nuclear Structure

Theory: Nucleon Numbers, Isotopes, and Nuclear Notation

Introduction to Atomic Structure

All atoms consist of a central nucleus containing protons and neutrons, surrounded by electrons. Understanding the composition of the nucleus is fundamental to nuclear physics.

Kazakh Translation

Барлық атомдар протондар мен нейтрондарды қамтитын орталық ядродан және оны қоршаған электрондардан тұрады. Ядроның құрамын түсіну ядролық физиканың негізі болып табылады.

Basic atomic structure showing nucleus with protons and neutrons, surrounded by electrons

Nucleon Number vs Proton Number

Proton Number (Z)

The proton number (Z) is the number of protons in an atomic nucleus. This number:

Determines the element identity
Equals the atomic number in the periodic table
Determines the nuclear charge (+Ze)
In neutral atoms, equals the number of electrons

Kazakh Translation

Протон саны (Z) атом ядросындағы протондардың саны. Бұл сан элементтің дербестігін анықтайды, периодтық кестедегі атомдық нөмірге тең, ядролық зарядты анықтайды және бейтарап атомдарда электрондар санына тең.

Nucleon Number (A)

The nucleon number (A), also called mass number, is the total number of nucleons (protons + neutrons) in the nucleus:

A = Z + N

Where N is the neutron number.

Nucleus showing protons (red) and neutrons (blue)

Nuclear Notation

Nuclides are represented using the standard notation:

^A_ZX

Where:

A = Nucleon number (mass number) — top left
Z = Proton number (atomic number) — bottom left
X = Chemical symbol of the element

Examples of nuclear notation for different elements

Examples of Nuclear Notation:

¹₁H — Hydrogen (1 proton, 0 neutrons)
⁴₂He — Helium (2 protons, 2 neutrons)
¹²₆C — Carbon-12 (6 protons, 6 neutrons)
²³⁸₉₂U — Uranium-238 (92 protons, 146 neutrons)

Isotopes

are atoms of the same element that have:

The same proton number (Z)
Different neutron numbers (N)
Different nucleon numbers (A)
The same chemical properties
Different physical properties

Kazakh Translation

Изотоптар — бірдей элементтің атомдары, олардың бірдей протон саны (Z), әртүрлі нейтрон саны (N), әртүрлі нуклон саны (A), бірдей химиялық қасиеттері, бірақ әртүрлі физикалық қасиеттері бар.

Three isotopes of carbon: Carbon-12, Carbon-13, and Carbon-14

Examples of Isotopes:

Element	Isotope	Notation	Protons (Z)	Neutrons (N)	Nucleons (A)
Hydrogen	Protium	¹₁H	1	0	1
Hydrogen	Deuterium	²₁H	1	1	2
Hydrogen	Tritium	³₁H	1	2	3
Carbon	Carbon-12	¹²₆C	6	6	12
Carbon	Carbon-14	¹⁴₆C	6	8	14

Conservation Laws in Nuclear Processes

In all nuclear processes, certain quantities are conserved (remain constant):

1. Conservation of Nucleon Number

The total nucleon number (A) before = total nucleon number (A) after

2. Conservation of Charge (Proton Number)

The total charge (Z) before = total charge (Z) after

Alpha decay showing conservation of nucleon number and charge

Example of Nuclear Equation:

Alpha decay of Uranium-238:

²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He

Checking conservation:

Nucleon number: 238 = 234 + 4 ✓
Charge: 92 = 90 + 2 ✓

Practice Questions

Question 1 (Easy):

For ¹⁶₈O, determine:

The proton number
The nucleon number
The neutron number

Answer

a) Proton number (Z) = 8
b) Nucleon number (A) = 16
c) Neutron number (N) = A — Z = 16 — 8 = 8

Question 2 (Medium):

Identify which of the following are isotopes of the same element:

¹⁴₆C, ¹²₆C, ¹⁴₇N, ¹³₆C

Answer

¹⁴₆C, ¹²₆C, and ¹³₆C are isotopes of carbon because they all have the same proton number (Z = 6) but different nucleon numbers.
¹⁴₇N is nitrogen, not carbon, because it has Z = 7.

Question 3 (Medium):

Complete the nuclear equation and identify the unknown nuclide X:

⁹₄Be + ⁴₂He → ¹²₆C + X

Answer

Using conservation laws:
Nucleon number: 9 + 4 = 12 + A_X, so A_X = 1
Charge: 4 + 2 = 6 + Z_X, so Z_X = 0
Therefore, X = ¹₀n (a neutron)

Question 4 (Critical Thinking):

Explain why isotopes of the same element have identical chemical properties but different physical properties. Use the example of carbon-12 and carbon-14 to illustrate your answer.

Answer

Chemical properties: Determined by electron configuration, which depends only on proton number (Z). Since isotopes have the same Z, they have identical electron arrangements and therefore identical chemical behavior.

Physical properties: Depend on nuclear mass and nuclear stability. Carbon-12 and carbon-14 both have 6 protons but different neutron numbers (6 vs 8), giving them different masses (12 vs 14) and different nuclear stability (C-12 is stable, C-14 is radioactive with half-life 5,730 years).

Example: Both C-12 and C-14 form the same chemical compounds (like CO₂) and participate in identical chemical reactions, but C-14 can be detected through its radioactive decay, making it useful for carbon dating.

🧠 Memorization Exercises

Exercises on Memorizing Terms

Exercise 1: Fill in the Blanks

The _______ number (Z) determines the element’s identity.
The _______ number (A) is the total number of protons and neutrons.
Isotopes have the same _______ number but different _______ numbers.
In nuclear notation ^A_ZX, the A represents the _______ number.
The neutron number is calculated as N = _______ — _______.

Answer

1. proton
2. nucleon (or mass)
3. proton, neutron
4. nucleon (or mass)
5. A, Z

Exercise 2: Nuclear Notation Practice

Write the nuclear notation for the following:

Lithium with 3 protons and 4 neutrons
Oxygen with 8 protons and 8 neutrons
Iron with 26 protons and 30 neutrons
Gold with 79 protons and 118 neutrons

Answer

1. ⁷₃Li (A = 3 + 4 = 7)
2. ¹⁶₈O (A = 8 + 8 = 16)
3. ⁵⁶₂₆Fe (A = 26 + 30 = 56)
4. ¹⁹⁷₇₉Au (A = 79 + 118 = 197)

Exercise 3: Conservation Laws

Check if the following nuclear equations satisfy conservation laws:

⁷₃Li + ¹₁H → ⁴₂He + ⁴₂He
²³⁵₉₂U + ¹₀n → ¹⁴⁴₅₆Ba + ⁸⁹₃₆Kr + 3¹₀n
¹⁴₆C → ¹⁴₇N + ⁰_-1e

Answer

1. A: 7 + 1 = 4 + 4 ✓ (8 = 8); Z: 3 + 1 = 2 + 2 ✓ (4 = 4)
2. A: 235 + 1 = 144 + 89 + 3(1) ✓ (236 = 236); Z: 92 + 0 = 56 + 36 + 0 ✓ (92 = 92)
3. A: 14 = 14 + 0 ✓ (14 = 14); Z: 6 = 7 + (-1) ✓ (6 = 6)
All equations satisfy conservation laws.

📺 Educational Video

Video Tutorial: Atomic and Nuclear Structure

Additional Resources:

🔬 Problem Solving Examples

Worked Examples

Example 1: Analyzing Isotopes

Problem: Uranium has several isotopes. Consider ²³⁵₉₂U and ²³⁸₉₂U.

Calculate the number of neutrons in each isotope
Explain why they are isotopes
Determine which isotope is heavier and by how many neutrons

🎤 Audio Solution

Detailed Solution with Pronunciation

Step 1: Calculate neutrons (pronounced: NEW-trons)

For ²³⁵₉₂U: N = A — Z = 235 — 92 = 143 neutrons

For ²³⁸₉₂U: N = A — Z = 238 — 92 = 146 neutrons

Step 2: Why they are isotopes

Both have the same proton number (Z = 92), making them uranium atoms

They have different nucleon numbers (235 vs 238), so different neutron numbers

Step 3: Mass comparison

U-238 is heavier than U-235 by 146 — 143 = 3 neutrons

This makes U-238 about 3 atomic mass units heavier

📝 Quick Solution

Brief Solution

1. Neutron calculation:

²³⁵₉₂U: N = 235 — 92 = 143

²³⁸₉₂U: N = 238 — 92 = 146

2. Isotopes because:

Same Z (92), different A (235 vs 238)

3. Mass difference:

U-238 heavier by 3 neutrons

Example 2: Nuclear Equation Balancing

Problem: Complete and balance the following nuclear equation for beta decay:

¹⁴₆C → ? + ⁰_-1e

🎤 Audio Solution

Detailed Solution with Pronunciation

Step 1: Apply conservation of nucleon number

Before decay: A = 14

After decay: A = A_unknown + 0

Therefore: A_unknown = 14

Step 2: Apply conservation of charge

Before decay: Z = 6

After decay: Z = Z_unknown + (-1)

Therefore: Z_unknown = 6 + 1 = 7

Step 3: Identify the product

Element with Z = 7 is nitrogen (N)

Complete equation: ¹⁴₆C → ¹⁴₇N + ⁰_-1e

📝 Quick Solution

Brief Solution

Conservation laws:

Nucleon number: 14 = A + 0, so A = 14

Charge: 6 = Z + (-1), so Z = 7

Answer:

¹⁴₆C → ¹⁴₇N + ⁰_-1e

Check: 14 = 14 + 0 ✓, 6 = 7 + (-1) ✓

🔬 Investigation Task

Interactive Simulation

Use this PhET simulation to build atoms and explore isotopes:

Investigation Questions:

Build three isotopes of carbon. How do their masses compare?
What happens to the element identity when you change the number of protons?
Create an atom with 8 protons and 10 neutrons. Write its nuclear notation.
Why doesn’t changing the number of electrons affect the nuclear notation?

Brief Answers

1. Carbon isotopes have masses 12, 13, and 14 (corresponding to C-12, C-13, C-14)
2. Element identity changes completely — different number of protons = different element
3. ¹⁸₈O (oxygen-18)
4. Nuclear notation only shows nuclear composition; electrons don’t affect nuclear identity

👥 Group/Pair Activity

Collaborative Learning Activity

Work with your partner or group to complete this isotope identification challenge:

Discussion Points:

Why are some isotopes stable while others are radioactive?
How do neutron-to-proton ratios affect nuclear stability?
What practical applications do different isotopes have?
How are artificial isotopes created in laboratories?

Group Challenge Activities:

Create isotope «trading cards» with properties of different isotopes
Build atomic models using different colored objects for protons, neutrons, and electrons
Design a nuclear equation balancing game
Research and present on medical applications of radioisotopes

✏️ Individual Assessment

Structured Questions — Individual Work

Question 1 (Analysis):

The element chlorine exists naturally as two isotopes: ³⁵₁₇Cl (75% abundance) and ³⁷₁₇Cl (25% abundance).

Calculate the number of neutrons in each isotope.
Explain why both are classified as chlorine atoms.
Calculate the average atomic mass of chlorine.
Discuss why the atomic mass on the periodic table (35.45) is not a whole number.
Predict which isotope would be more common in nature and explain your reasoning.

Answer

a) ³⁵₁₇Cl: N = 35 — 17 = 18 neutrons; ³⁷₁₇Cl: N = 37 — 17 = 20 neutrons
b) Both have Z = 17, so same number of protons = same element identity
c) Average mass = (35 × 0.75) + (37 × 0.25) = 26.25 + 9.25 = 35.5
d) Atomic mass is weighted average of isotope masses, not whole number
e) Cl-35 is more common (75% vs 25%) — lighter isotopes often more abundant due to nuclear stability considerations

Question 2 (Synthesis):

A student is studying nuclear reactions and encounters the following equation:

²₁H + ³₁H → ⁴₂He + X

Identify the unknown particle X using conservation laws.
Name the reactants and products in this equation.
Calculate the total number of nucleons before and after the reaction.
Explain what type of nuclear process this represents.
Discuss the energy implications of this reaction.

Answer

a) Using conservation: A: 2 + 3 = 4 + A_X, so A_X = 1; Z: 1 + 1 = 2 + Z_X, so Z_X = 0. Therefore X = ¹₀n (neutron)
b) Reactants: deuterium (²₁H) and tritium (³₁H); Products: helium-4 and neutron
c) Before: 2 + 3 = 5 nucleons; After: 4 + 1 = 5 nucleons (conserved)
d) Nuclear fusion — light nuclei combining to form heavier nucleus
e) Fusion releases energy because products have lower total mass than reactants (mass-energy equivalence)

Question 3 (Evaluation):

Compare and contrast the three hydrogen isotopes: ¹₁H, ²₁H, and ³₁H.

Create a comparison table showing their nuclear composition.
Explain why they all have identical chemical properties.
Describe how their physical properties differ.
Discuss their relative abundance and stability.
Evaluate their applications in science and technology.

Answer

a) Protium: 1p, 0n; Deuterium: 1p, 1n; Tritium: 1p, 2n
b) Same electron configuration (1 electron) determines chemical behavior
c) Different masses (1:2:3 ratio), different nuclear stability (tritium radioactive)
d) Protium most abundant (99.98%), deuterium rare (0.02%), tritium trace/artificial
e) Protium: fuel, reducing agent; Deuterium: heavy water, NMR; Tritium: fusion fuel, radioluminescent devices

Question 4 (Critical Thinking):

A nuclear medicine technologist uses ^99m₄₃Tc for medical imaging. The ‘m’ indicates a metastable state.

Determine the nuclear composition of this isotope.
Explain what «metastable» means in nuclear terms.
Why is this isotope particularly suitable for medical imaging?
Compare its properties to ⁹⁹₄₃Tc (ground state).
Discuss the safety considerations when handling this isotope.

Answer

a) 43 protons, 99-43 = 56 neutrons, total 99 nucleons
b) Metastable = excited nuclear state with longer-than-usual lifetime before decay
c) Ideal half-life (6 hours), pure gamma emission, no beta/alpha particles, readily available
d) Same composition but higher energy state; decays to ⁹⁹₄₃Tc ground state
e) Short half-life minimizes exposure; gamma rays require shielding; no ingestion/inhalation; proper disposal

Question 5 (Application):

Carbon dating uses the ratio of ¹⁴₆C to ¹²₆C to determine the age of organic materials.

Explain why both isotopes are chemically identical in living organisms.
Describe what happens to the C-14/C-12 ratio after an organism dies.
Write the nuclear equation for C-14 decay.
Calculate how many neutrons are gained or lost in this decay process.
Evaluate the limitations of carbon dating and suggest alternative dating methods.

Answer

a) Same Z (6 protons) = same electron configuration = identical chemical behavior
b) C-14 decays (radioactive) while C-12 remains constant (stable), so ratio decreases
c) ¹⁴₆C → ¹⁴₇N + ⁰_-1e
d) No change in neutron number: both parent and daughter have same A, neutron converts to proton
e) Limitations: ~50,000 year limit, contamination issues. Alternatives: K-Ar dating, U-Pb dating for older samples

🔗 Additional Resources

Useful Links and References

📚 Study Materials:

🎥 Video Resources:

🧮 Interactive Tools:

📖 Reference Materials:

🤔 Lesson Reflection

Reflection Questions

Think about your learning today:

💡 Understanding:

Can you clearly distinguish between nucleon number and proton number in your own words?
How does understanding isotopes help explain the non-whole-number atomic masses on the periodic table?
What connections can you make between nuclear notation and the information it conveys?
How do conservation laws help you understand nuclear processes?

🎯 Application:

How would you explain to someone why carbon-12 and carbon-14 behave chemically the same but differ physically?
What practical applications of isotopes can you think of beyond those discussed?
How might this knowledge apply to understanding nuclear energy or medical procedures?
Which problem-solving strategies were most effective for nuclear equations?

🔄 Next Steps:

What aspects of nuclear physics would you like to explore further?
How confident do you feel about writing and balancing nuclear equations?
What questions do you still have about atomic structure and isotopes?
How might this knowledge connect to other areas of physics you’ve studied?

📝 Self-Assessment Scale (1-5):

Rate your confidence in:

Distinguishing nucleon and proton numbers: ___/5
Understanding isotopes: ___/5
Using nuclear notation ^A_ZX: ___/5
Applying conservation laws: ___/5
Balancing nuclear equations: ___/5

🎯 Learning Goals Achieved:

☐ I can distinguish between nucleon number and proton number
☐ I understand that isotopes have the same proton number but different neutron numbers
☐ I can use nuclear notation ^A_ZX correctly
☐ I understand conservation of nucleon number and charge in nuclear processes
☐ I can balance nuclear equations using conservation laws

🌟 Key Insights:

«Nuclear notation is like a passport for atoms — it tells us exactly who they are (element identity from Z) and their ‘weight’ (from A). Isotopes are like family members — same last name (element) but different ages (masses). Conservation laws in nuclear processes are like accounting — what goes in must equal what comes out!»