Subjects

Subjects

More

Search

AI Knowunity

Understanding Atomic Structure and Electron Arrangement in AQA Physics

Open

1338

10

A

Alice Stevens

19/06/2023

Physics

Aqa physics paper 1

Subjects

/

Physics

Understanding Atomic Structure and Electron Arrangement in AQA Physics

The development of our understanding of atomic structure has been shaped by several key scientists and their groundbreaking discoveries throughout history.

The journey began with Thomson's plum pudding model, but it was Rutherford's atomic model that revolutionized our understanding by proving the existence of a dense, positively-charged nucleus. Through his famous gold foil experiment, Rutherford demonstrated that atoms were mostly empty space with a concentrated central nucleus, leading to what became known as the nuclear model. Niels Bohr further refined this model by showing that electrons (negatively charged particles) orbit the nucleus in specific energy levels or shells, rather than randomly. This explained how electrons could maintain stable orbits without losing energy and crashing into the nucleus.

A crucial breakthrough came when James Chadwick discovered the neutron in 1932, completing our basic understanding of atomic structure. Through his experiments with beryllium radiation, Chadwick identified neutral particles with approximately the same mass as protons, solving the mystery of atomic mass numbers. This discovery explained why elements could have different isotopes and led to our modern understanding of radioactive decay. The atomic model we use today shows that atoms consist of a nucleus containing protons (discovered by Rutherford) and neutrons (discovered by Chadwick), with electrons orbiting in shells around the nucleus. This knowledge forms the foundation of the periodic table, where elements are arranged by their atomic numbers (number of protons) and electron arrangements. Understanding atomic structure is essential for explaining chemical reactions, radioactivity, and the behavior of elements in both physics and chemistry.

...

19/06/2023

17980

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

Understanding Atomic Structure and Subatomic Particles

The Atomic Structure Physics forms the foundation of matter, consisting of a positively charged nucleus surrounded by negatively charged electrons. The nucleus, containing protons and neutrons, is remarkably compact - about 10,000 times smaller than the atom's total radius of approximately 1 x 10⁻¹⁰ meters. Despite its tiny size, the nucleus holds nearly all of the atom's mass.

Definition: An atom consists of three main subatomic particles: protons (relative mass 1, charge +1), neutrons (relative mass 1, charge 0), and electrons (relative mass 0.0005, charge -1).

Elements are distinguished by their atomic number (number of protons), while isotopes of the same element have different numbers of neutrons. In neutral atoms, the number of protons equals the number of electrons, resulting in no net charge. When atoms gain or lose electrons, they become ions with either negative or positive charges respectively.

Electromagnetic (EM) radiation plays a crucial role in electron behavior. When electrons absorb energy, they can move to higher energy levels farther from the nucleus. Conversely, when electrons fall to lower energy levels, they emit EM radiation. If an electron gains sufficient energy, it can completely escape the atom, forming a positive ion.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

Evolution of Atomic Models Through History

The understanding of atomic structure evolved significantly through various models. In 1800, Dalton proposed that matter consisted of indivisible spheres called atoms. The Rutherford atomic model emerged from the famous gold foil experiment, which revealed that atoms were mostly empty space with a dense, positive nucleus.

Highlight: The gold foil experiment showed that:

  • Most alpha particles passed straight through, indicating mostly empty space
  • Some particles deflected slightly, suggesting a charged nucleus
  • Few particles reflected back, proving a dense, massive nucleus

The Niels Bohr atomic model addressed a critical flaw in Rutherford's model. If electrons simply orbited the nucleus like planets, they would spiral inward and collapse. Bohr proposed that electrons (negatively charged particles) have been shown to orbit the nucleus at distances in fixed energy levels or "orbitals."

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

James Chadwick's Contributions and Radiation

James Chadwick's discovery of the neutron in the 1930s completed our modern understanding of atomic structure. James Chadwick experiment provided crucial evidence for the existence of neutrons, neutral particles within the nucleus alongside protons.

Vocabulary: Radioactive decay is a random process where unstable nuclei emit radiation to become more stable. Activity, measured in becquerels (Bq), represents the decay rate.

Three main types of radiation exist:

  1. Alpha (α) radiation: Highly ionizing but weakly penetrating helium nuclei
  2. Beta (β) radiation: Moderately ionizing and penetrating electrons
  3. Gamma (γ) radiation: Weakly ionizing but highly penetrating electromagnetic waves
Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

Half-Life and Radioactive Applications

Half-life represents the time required for half of a radioactive sample to decay. While individual atomic decay is unpredictable, half-life provides a reliable measure for large numbers of atoms. This concept has practical applications in various fields.

Example: If a sample's activity decreases from 80 to 20 counts over 10 minutes, the half-life is 5 minutes because:

  • First half-life: 80 → 40
  • Second half-life: 40 → 20

Radioactive materials with different half-lives serve various purposes. Short half-life isotopes pose intense but brief radiation risks, while long half-life isotopes, like Americium in smoke detectors, provide sustained but lower-level radiation. Contamination occurs when radioactive atoms transfer to other materials, creating ongoing radiation hazards.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

Understanding Irradiation and Nuclear Processes in Physics

Atomic Structure Physics and radiation processes are fundamental concepts in nuclear physics. Irradiation occurs when an object is exposed to radiation without becoming radioactive itself. The radiation source emits particles or waves that interact with the target object for a limited time period.

Background radiation exists naturally in our environment from multiple sources. This includes cosmic rays from space, radiation from underground rocks, and residual nuclear fallout. Medical facilities also contribute to background radiation through diagnostic equipment. The standard measurement unit for radiation dose is the Sievert (Sv).

Medical applications utilize radioactive tracers like Technetium-99m, which has specific properties making it ideal for diagnostic imaging. With a Radioactive decay half-life of 6 hours, it decays into a safe isotope that the body can eliminate naturally. As a gamma emitter, it can penetrate body tissues without significant absorption, allowing doctors to track its movement through the body while minimizing radiation exposure.

Definition: Irradiation is the process of exposing an object to radiation without making it radioactive. The radiation interacts with the object temporarily but does not leave behind radioactive particles.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

Nuclear Fission and Fusion Processes

Nuclear fission involves splitting large unstable nuclei into smaller ones. While spontaneous fission is rare, the process typically begins when an unstable nucleus absorbs a neutron. This triggers the nucleus to split into two roughly equal parts, releasing additional neutrons and gamma rays along with significant energy.

The released neutrons can trigger a chain reaction by colliding with other radioactive nuclei. Each subsequent split releases more neutrons and energy, creating a self-sustaining process. In nuclear power plants, this chain reaction is carefully controlled, while nuclear weapons allow it to proceed exponentially.

The Rutherford atomic model helped explain how nuclear processes work at the atomic level. The model, which was later refined by Niels Bohr atomic model, showed how electrons (negatively charged particles) have been shown to orbit the nucleus at distances that affect nuclear reactions.

Highlight: Nuclear fusion, unlike fission, combines small nuclei to form larger ones. This process powers the Sun and releases enormous energy, though creating sustainable fusion reactions on Earth remains challenging.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

Energy Transfer and Storage Systems

Energy exists in various forms and can transfer between different storage systems. When analyzing energy changes, it's crucial to consider the entire system - defined as an object or group of objects that interact. Common scenarios include projectile motion, collisions, acceleration, and thermal processes.

Kinetic energy of moving objects can be calculated using the equation Ek = ½mv², where m is mass and v is velocity. Similarly, gravitational potential energy follows the equation Ep = mgh, where h is height and g is gravitational field strength. These equations help quantify energy transformations in physical systems.

The specific heat capacity of materials determines how much energy is needed to change their temperature. This relationship is expressed as ΔE = mcΔθ, where m is mass, c is specific heat capacity, and Δθ is temperature change.

Example: When a car brakes, kinetic energy transforms into thermal energy through friction. The energy isn't lost but converts to a less useful form, demonstrating energy conservation.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

Electrical Circuits and Current Flow

Understanding electrical circuits requires knowledge of charge flow, current, and potential difference. Current (I) represents the rate of charge flow through a circuit, measured in amperes (A). The relationship between charge flow (Q), current, and time (t) follows Q = It.

In circuit components, resistance (R) affects current flow according to Ohm's Law: V = IR, where V is potential difference. Different components exhibit varying resistance characteristics. While some maintain constant resistance (ohmic conductors), others like thermistors and light-dependent resistors (LDRs) show variable resistance depending on conditions.

Standard circuit symbols provide a universal language for representing electrical components. These include basic elements like cells, switches, and resistors, as well as more complex components like diodes and variable resistors.

Vocabulary: Potential difference (voltage) is the driving force that moves electrical charge through a circuit, measured in volts (V).

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

View

Understanding Electrical Circuits and Safety in Physics

Atomic Structure Physics fundamentals help us understand how electrical circuits work at their most basic level. When examining current flow and potential difference in circuits, we must consider how electrons move through different arrangements of components.

In series circuits, components are connected end-to-end in a single path. The current remains constant throughout the circuit while the potential difference is divided among the components. This follows a key mathematical relationship where the total resistance equals the sum of individual component resistances (Rtotal = R₁ + R₂). This principle is crucial for designing circuits where precise voltage drops are needed across specific components.

For parallel circuits, components are connected across different branches. Each branch experiences the same potential difference, while the total current splits between the paths. The total resistance in parallel is always less than the smallest individual resistance, making parallel circuits ideal for applications requiring multiple devices to operate independently at the same voltage.

Definition: A thermistor is a temperature-dependent resistor whose resistance decreases as temperature increases, while a Light Dependent Resistor (LDR) shows decreased resistance with increased light intensity.

Highlight: In UK domestic electricity, the mains supply operates at 230V with a frequency of 50Hz, using a three-core cable system for safety and proper operation.

Can't find what you're looking for? Explore other subjects.

Knowunity is the #1 education app in five European countries

Knowunity has been named a featured story on Apple and has regularly topped the app store charts in the education category in Germany, Italy, Poland, Switzerland, and the United Kingdom. Join Knowunity today and help millions of students around the world.

Ranked #1 Education App

Download in

Google Play

Download in

App Store

Knowunity is the #1 education app in five European countries

4.9+

Average app rating

17 M

Pupils love Knowunity

#1

In education app charts in 17 countries

950 K+

Students have uploaded notes

Still not convinced? See what other students are saying...

iOS User

I love this app so much, I also use it daily. I recommend Knowunity to everyone!!! I went from a D to an A with it :D

Philip, iOS User

The app is very simple and well designed. So far I have always found everything I was looking for :D

Lena, iOS user

I love this app ❤️ I actually use it every time I study.

Subjects

/

Physics

Understanding Atomic Structure and Electron Arrangement in AQA Physics

A

Alice Stevens

@alicestevens_idux

·

307 Followers

Follow

The development of our understanding of atomic structure has been shaped by several key scientists and their groundbreaking discoveries throughout history.

The journey began with Thomson's plum pudding model, but it was Rutherford's atomic model that revolutionized our understanding by proving the existence of a dense, positively-charged nucleus. Through his famous gold foil experiment, Rutherford demonstrated that atoms were mostly empty space with a concentrated central nucleus, leading to what became known as the nuclear model. Niels Bohr further refined this model by showing that electrons (negatively charged particles) orbit the nucleus in specific energy levels or shells, rather than randomly. This explained how electrons could maintain stable orbits without losing energy and crashing into the nucleus.

A crucial breakthrough came when James Chadwick discovered the neutron in 1932, completing our basic understanding of atomic structure. Through his experiments with beryllium radiation, Chadwick identified neutral particles with approximately the same mass as protons, solving the mystery of atomic mass numbers. This discovery explained why elements could have different isotopes and led to our modern understanding of radioactive decay. The atomic model we use today shows that atoms consist of a nucleus containing protons (discovered by Rutherford) and neutrons (discovered by Chadwick), with electrons orbiting in shells around the nucleus. This knowledge forms the foundation of the periodic table, where elements are arranged by their atomic numbers (number of protons) and electron arrangements. Understanding atomic structure is essential for explaining chemical reactions, radioactivity, and the behavior of elements in both physics and chemistry.

...

19/06/2023

17980

 

10/11

 

Physics

1338

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Understanding Atomic Structure and Subatomic Particles

The Atomic Structure Physics forms the foundation of matter, consisting of a positively charged nucleus surrounded by negatively charged electrons. The nucleus, containing protons and neutrons, is remarkably compact - about 10,000 times smaller than the atom's total radius of approximately 1 x 10⁻¹⁰ meters. Despite its tiny size, the nucleus holds nearly all of the atom's mass.

Definition: An atom consists of three main subatomic particles: protons (relative mass 1, charge +1), neutrons (relative mass 1, charge 0), and electrons (relative mass 0.0005, charge -1).

Elements are distinguished by their atomic number (number of protons), while isotopes of the same element have different numbers of neutrons. In neutral atoms, the number of protons equals the number of electrons, resulting in no net charge. When atoms gain or lose electrons, they become ions with either negative or positive charges respectively.

Electromagnetic (EM) radiation plays a crucial role in electron behavior. When electrons absorb energy, they can move to higher energy levels farther from the nucleus. Conversely, when electrons fall to lower energy levels, they emit EM radiation. If an electron gains sufficient energy, it can completely escape the atom, forming a positive ion.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Evolution of Atomic Models Through History

The understanding of atomic structure evolved significantly through various models. In 1800, Dalton proposed that matter consisted of indivisible spheres called atoms. The Rutherford atomic model emerged from the famous gold foil experiment, which revealed that atoms were mostly empty space with a dense, positive nucleus.

Highlight: The gold foil experiment showed that:

  • Most alpha particles passed straight through, indicating mostly empty space
  • Some particles deflected slightly, suggesting a charged nucleus
  • Few particles reflected back, proving a dense, massive nucleus

The Niels Bohr atomic model addressed a critical flaw in Rutherford's model. If electrons simply orbited the nucleus like planets, they would spiral inward and collapse. Bohr proposed that electrons (negatively charged particles) have been shown to orbit the nucleus at distances in fixed energy levels or "orbitals."

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

James Chadwick's Contributions and Radiation

James Chadwick's discovery of the neutron in the 1930s completed our modern understanding of atomic structure. James Chadwick experiment provided crucial evidence for the existence of neutrons, neutral particles within the nucleus alongside protons.

Vocabulary: Radioactive decay is a random process where unstable nuclei emit radiation to become more stable. Activity, measured in becquerels (Bq), represents the decay rate.

Three main types of radiation exist:

  1. Alpha (α) radiation: Highly ionizing but weakly penetrating helium nuclei
  2. Beta (β) radiation: Moderately ionizing and penetrating electrons
  3. Gamma (γ) radiation: Weakly ionizing but highly penetrating electromagnetic waves
Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Half-Life and Radioactive Applications

Half-life represents the time required for half of a radioactive sample to decay. While individual atomic decay is unpredictable, half-life provides a reliable measure for large numbers of atoms. This concept has practical applications in various fields.

Example: If a sample's activity decreases from 80 to 20 counts over 10 minutes, the half-life is 5 minutes because:

  • First half-life: 80 → 40
  • Second half-life: 40 → 20

Radioactive materials with different half-lives serve various purposes. Short half-life isotopes pose intense but brief radiation risks, while long half-life isotopes, like Americium in smoke detectors, provide sustained but lower-level radiation. Contamination occurs when radioactive atoms transfer to other materials, creating ongoing radiation hazards.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Understanding Irradiation and Nuclear Processes in Physics

Atomic Structure Physics and radiation processes are fundamental concepts in nuclear physics. Irradiation occurs when an object is exposed to radiation without becoming radioactive itself. The radiation source emits particles or waves that interact with the target object for a limited time period.

Background radiation exists naturally in our environment from multiple sources. This includes cosmic rays from space, radiation from underground rocks, and residual nuclear fallout. Medical facilities also contribute to background radiation through diagnostic equipment. The standard measurement unit for radiation dose is the Sievert (Sv).

Medical applications utilize radioactive tracers like Technetium-99m, which has specific properties making it ideal for diagnostic imaging. With a Radioactive decay half-life of 6 hours, it decays into a safe isotope that the body can eliminate naturally. As a gamma emitter, it can penetrate body tissues without significant absorption, allowing doctors to track its movement through the body while minimizing radiation exposure.

Definition: Irradiation is the process of exposing an object to radiation without making it radioactive. The radiation interacts with the object temporarily but does not leave behind radioactive particles.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Nuclear Fission and Fusion Processes

Nuclear fission involves splitting large unstable nuclei into smaller ones. While spontaneous fission is rare, the process typically begins when an unstable nucleus absorbs a neutron. This triggers the nucleus to split into two roughly equal parts, releasing additional neutrons and gamma rays along with significant energy.

The released neutrons can trigger a chain reaction by colliding with other radioactive nuclei. Each subsequent split releases more neutrons and energy, creating a self-sustaining process. In nuclear power plants, this chain reaction is carefully controlled, while nuclear weapons allow it to proceed exponentially.

The Rutherford atomic model helped explain how nuclear processes work at the atomic level. The model, which was later refined by Niels Bohr atomic model, showed how electrons (negatively charged particles) have been shown to orbit the nucleus at distances that affect nuclear reactions.

Highlight: Nuclear fusion, unlike fission, combines small nuclei to form larger ones. This process powers the Sun and releases enormous energy, though creating sustainable fusion reactions on Earth remains challenging.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Energy Transfer and Storage Systems

Energy exists in various forms and can transfer between different storage systems. When analyzing energy changes, it's crucial to consider the entire system - defined as an object or group of objects that interact. Common scenarios include projectile motion, collisions, acceleration, and thermal processes.

Kinetic energy of moving objects can be calculated using the equation Ek = ½mv², where m is mass and v is velocity. Similarly, gravitational potential energy follows the equation Ep = mgh, where h is height and g is gravitational field strength. These equations help quantify energy transformations in physical systems.

The specific heat capacity of materials determines how much energy is needed to change their temperature. This relationship is expressed as ΔE = mcΔθ, where m is mass, c is specific heat capacity, and Δθ is temperature change.

Example: When a car brakes, kinetic energy transforms into thermal energy through friction. The energy isn't lost but converts to a less useful form, demonstrating energy conservation.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Electrical Circuits and Current Flow

Understanding electrical circuits requires knowledge of charge flow, current, and potential difference. Current (I) represents the rate of charge flow through a circuit, measured in amperes (A). The relationship between charge flow (Q), current, and time (t) follows Q = It.

In circuit components, resistance (R) affects current flow according to Ohm's Law: V = IR, where V is potential difference. Different components exhibit varying resistance characteristics. While some maintain constant resistance (ohmic conductors), others like thermistors and light-dependent resistors (LDRs) show variable resistance depending on conditions.

Standard circuit symbols provide a universal language for representing electrical components. These include basic elements like cells, switches, and resistors, as well as more complex components like diodes and variable resistors.

Vocabulary: Potential difference (voltage) is the driving force that moves electrical charge through a circuit, measured in volts (V).

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Understanding Electrical Circuits and Safety in Physics

Atomic Structure Physics fundamentals help us understand how electrical circuits work at their most basic level. When examining current flow and potential difference in circuits, we must consider how electrons move through different arrangements of components.

In series circuits, components are connected end-to-end in a single path. The current remains constant throughout the circuit while the potential difference is divided among the components. This follows a key mathematical relationship where the total resistance equals the sum of individual component resistances (Rtotal = R₁ + R₂). This principle is crucial for designing circuits where precise voltage drops are needed across specific components.

For parallel circuits, components are connected across different branches. Each branch experiences the same potential difference, while the total current splits between the paths. The total resistance in parallel is always less than the smallest individual resistance, making parallel circuits ideal for applications requiring multiple devices to operate independently at the same voltage.

Definition: A thermistor is a temperature-dependent resistor whose resistance decreases as temperature increases, while a Light Dependent Resistor (LDR) shows decreased resistance with increased light intensity.

Highlight: In UK domestic electricity, the mains supply operates at 230V with a frequency of 50Hz, using a three-core cable system for safety and proper operation.

Atomic Structure electron arrangement. electrons lie at different distances from the nucleus (different energy levels). The electron arrange

Sign up to see the content. It's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Domestic Electricity Safety and Applications

The safe implementation of domestic electricity relies on proper understanding of the three-wire system used in household wiring. Each wire serves a specific purpose and is color-coded for safety: brown for live, blue for neutral, and green/yellow stripes for earth.

The live wire carries the alternating potential difference of approximately 230V, while the neutral wire completes the circuit and typically stays near earth potential (0V). The earth wire acts as a crucial safety feature, only conducting current in fault conditions to prevent appliances from becoming dangerously "live."

Understanding these concepts is essential for both practical applications and safety. Modern electrical systems incorporate various safety devices like circuit breakers and residual current devices (RCDs) that rely on these principles to protect users from electrical hazards.

Example: In a household circuit, if a fault occurs causing the metal casing of an appliance to become live, the earth wire provides a low-resistance path for the current to flow safely to ground, triggering protective devices and preventing electric shock.

Vocabulary: Alternating Current (AC) is the type of electrical current used in homes where the direction of current flow periodically reverses, typically 50 times per second in the UK (50Hz).

Can't find what you're looking for? Explore other subjects.

Knowunity is the #1 education app in five European countries

Knowunity has been named a featured story on Apple and has regularly topped the app store charts in the education category in Germany, Italy, Poland, Switzerland, and the United Kingdom. Join Knowunity today and help millions of students around the world.

Ranked #1 Education App

Download in

Google Play

Download in

App Store

Knowunity is the #1 education app in five European countries

4.9+

Average app rating

17 M

Pupils love Knowunity

#1

In education app charts in 17 countries

950 K+

Students have uploaded notes

Still not convinced? See what other students are saying...

iOS User

I love this app so much, I also use it daily. I recommend Knowunity to everyone!!! I went from a D to an A with it :D

Philip, iOS User

The app is very simple and well designed. So far I have always found everything I was looking for :D

Lena, iOS user

I love this app ❤️ I actually use it every time I study.