📝 Exam Questions — Chemistry

Atoms are the fundamental building blocks of matter, and they combine in various ways to form all substances around us. (a) Define the term 'atom'. [2] (b) State one key difference between an element and a compound. [2]

Uranium has several isotopes, including 235 92U and 238 92U. (a) Explain why isotopes of an element have identical chemical properties. [3] (b) Deduce the number of neutrons in the two isotopes 235 92U and 238 92U. [4]

Uranium is a heavy element often used in nuclear power and research. Its atomic structure is crucial to understanding its properties. (a) An isotope of uranium has a mass number of 238 and an atomic number of 92. Calculate the number of neutrons in this isotope. [3] (b) A different isotope of uranium has 143 neutrons. Determine its mass number and compare it to the isotope in part (a). [6]

Subatomic particles are the fundamental building blocks of atoms, each possessing distinct properties. These properties, such as charge and mass, are crucial in understanding atomic structure. (a) State the relative charge of a proton and an electron. [2] (b) Identify the subatomic particle with the largest relative mass and the particle with a relative mass of approximately 1/1836. [3]

The identity and characteristics of an atom are determined by its subatomic particles. (a) Determine the number of protons, neutrons, and electrons in a neutral atom of Sodium-23 (atomic number 11). [4] (b) Deduce how a change in the number of neutrons affects the atomic number and mass number of an atom. [3]

Early models of the atom, such as Rutherford's, described a nucleus containing protons and electrons orbiting it. The discovery of the neutron significantly changed this understanding. (a) Explain why the discovery of the neutron was important for understanding atomic structure. [4] (b) State the approximate date of the neutron's discovery. [2]

The stability of atomic nuclei is influenced by the ratio of neutrons to protons. Fig 1.1 shows a graph of neutron number versus proton number for stable isotopes across the periodic table. (a) Analyse the trend shown for elements with higher atomic numbers, explaining why this trend is observed. [6] (b) Using the information from Fig 1.1, derive an approximate ratio of neutrons to protons for elements with atomic number around 80. [4]

Atoms are the fundamental building blocks of matter, each composed of various subatomic particles. (a) Name the three fundamental subatomic particles. [2] (b) State the location of the nucleus within an atom. [2]

The identity and properties of an atom are fundamentally determined by the number of subatomic particles it contains. (a) Define the term 'atomic number'. [2] (b) State what the mass number represents. [2]

The composition of an atom's nucleus dictates its fundamental characteristics. (a) An atom has 15 protons and 16 neutrons. Determine its atomic number and mass number. [3] (b) Explain why the atomic number uniquely identifies an element. [3]

The understanding of atomic structure has evolved significantly over time, from early solid-sphere models to more complex quantum mechanical descriptions. The Bohr model, while an improvement, still has limitations. (a) Discuss the limitations of the simple Bohr model of the atom. [5] (b) Evaluate the statement: 'An atom is mostly empty space'. [5]

The atom is composed of various subatomic particles, each contributing to its overall properties. (a) Describe the relative masses of protons, neutrons, and electrons. [3] (b) Explain why an atom is electrically neutral. [4]

Subatomic particles are fundamental to the structure of matter. Protons, neutrons, and electrons are the primary constituents of atoms. (a) Draw a representation of a single proton, indicating its relative charge and approximate relative mass. [3] (b) Label the key features on your drawing that differentiate it from an electron. [3]

The forces within the atomic nucleus are complex and profoundly influenced by its composition. (a) Discuss the role of neutrons in the stability of atomic nuclei, particularly for heavier elements. [6] (b) Evaluate why knowing only the atomic number is insufficient to determine the exact mass of an atom. [5]

The Periodic Table organises all known elements based on their properties and atomic structure. (a) Identify the main characteristic that defines an element. [2] (b) Give three examples of common elements. [3]

The fundamental properties of subatomic particles are often summarised in tables. Fig 1.1 provides a summary of the relative masses and relative charges for protons, neutrons, and electrons. Fig 1.1

(a) Interpret the information in Fig 1.1 to determine the subatomic particle with the highest relative charge magnitude. [4] (b) Deduce which subatomic particle would be most significantly deflected in an electric field, based on its relative charge and mass. [4]

The Rutherford model and subsequent refinements describe the atom as having a central nucleus surrounded by electrons. (a) Sketch a simple diagram of an atom, showing the nucleus and electron shells. [4] (b) Label the subatomic particles in your diagram and indicate their charges. [4]

Early investigations into the structure of the atom involved experiments that led to the discovery of subatomic particles. (a) Name the scientist credited with the discovery of the electron. [2] (b) Describe one key observation from the cathode ray tube experiment that led to the discovery of the electron. [3]

The nucleus of an atom contains protons and neutrons, which are collectively known as nucleons. (a) Calculate the total relative charge of a nucleus containing 8 protons and 8 neutrons. [3] (b) Explain why the mass of an atom is largely concentrated in its nucleus. [3]

The arrangement of subatomic particles within an atom dictates its properties. Understanding the roles of the nucleus and electrons is key to explaining atomic behaviour. (a) Describe the arrangement of electrons in electron shells, including their energy levels. [4] (b) Explain the role of the nucleus in determining the mass of an atom. [4]

An element can exist in different isotopic forms, each having a unique combination of subatomic particles. These differences can lead to variations in certain properties. (a) Discuss the main differences in physical properties between isotopes of the same element. [6] (b) Compare the number of protons, neutrons, and electrons in a neutral atom of 12 6C and a neutral atom of 14 6C. [4]

Chemical symbols are often used with nuclide notation to represent specific isotopes of elements. (a) Fig 1.2 shows the symbolic representation of an atom. Interpret the atomic number and mass number from this notation. [4] (b) Deduce the name of the element represented in Fig 1.2, given that its atomic number is 19. [4]

The composition of an atom's nucleus is fundamental to its identity and properties. (a) State the formula used to calculate the number of neutrons in an atom. [2] (b) Calculate the number of neutrons in an atom with mass number 35 and atomic number 17. [2]

Atoms are fundamental building blocks of matter, composed of subatomic particles. The number of these particles determines the identity and properties of an element. (a) Calculate the number of neutrons in an atom of oxygen-16 (atomic number 8). [3] (b) Determine the atomic number of an element if its atom has 15 protons. [3]

Atoms of the same element can exist in different forms called isotopes. (a) Give two examples of elements that have naturally occurring isotopes. [3] (b) State the key difference in atomic structure between two isotopes of the same element. [2]

Atoms are composed of various subatomic particles, each contributing to their overall properties. (a) Identify the two subatomic particles that make up the mass number. [2] (b) State how isotopes of an element differ in their atomic structure. [2]

Potassium is an element that exists naturally as two common isotopes, 39 19K and 41 19K. (a) Calculate the number of neutrons in an atom of 39 19K and 41 19K. [4] (b) Explain why these two atoms are considered isotopes of potassium. [4]

The structure of atoms can vary slightly even for the same element. (a) Define the term 'isotope'. [2] (b) Identify which subatomic particle differs in number between isotopes of the same element. [2]

Atoms are composed of a central nucleus surrounded by electrons. The arrangement and properties of these subatomic particles determine the characteristics of an element. (a) Describe the location of protons and neutrons within an atom. [3] (b) Explain why the overall charge of an atom is neutral, referring to the charges of its subatomic particles. [4]

The Periodic Table organises elements based on their atomic structure. Fig 1.1 shows a section of the Periodic Table. (a) Use Fig 1.1 to interpret the atomic number and mass number for the element Oxygen (O). [5] (b) Calculate the number of protons in an atom of Carbon (C) and the number of nucleons in an atom of Nitrogen (N) from Fig 1.1. [4]

The concept of atoms being the fundamental, indivisible particles of matter has evolved over time. Modern atomic theory describes atoms as composed of subatomic particles. (a) Evaluate the statement: 'All atoms of the same element are identical in every way.' [6] (b) Explain why the average atomic mass of an element is usually not a whole number. [3] (c) Calculate the number of neutrons in an isotope with mass number 14 and atomic number 7. [3]

The three main subatomic particles—protons, neutrons, and electrons—have distinct relative masses and charges. These properties influence how atoms behave and interact. (a) Discuss the significance of the relative mass of electrons compared to protons and neutrons in determining the overall mass of an atom. [6] (b) Compare the effect of an external electric field on a beam of protons, neutrons, and electrons. [4]

Experiments involving cathode rays and canal rays were instrumental in identifying subatomic particles and their properties. (a) Outline the experimental evidence that suggests electrons are fundamental particles. [4] (b) Compare the properties of cathode rays and canal rays, explaining how their deflections in electric and magnetic fields differ. [4]

Subatomic particles can be deflected by electric fields depending on their charge and mass. (a) Fig 1.1 shows three different subatomic particles, A, B, and C, entering a region with a uniform electric field. Identify which particle corresponds to a proton, electron, and neutron based on their paths. [3] (b) State the relative charge of the particle identified as a neutron in Fig 1.1. [2]

The fundamental particles within an atom define its chemical and physical nature. Understanding how changes to these particles affect the atom is crucial. (a) Analyse the implications of a change in atomic number versus a change in mass number on the identity and properties of an atom. [6] (b) Deduce the number of electrons in a neutral atom given its atomic number. [4]

The identity of an element is determined by its atomic number, while its mass number relates to the total number of nucleons. (a) An atom has 20 electrons and a mass number of 40. Determine its atomic number and the number of protons. [4] (b) Explain how the atomic number defines an element, even if the number of neutrons changes. [3]

The concept of the atom has evolved significantly over centuries, from philosophical ideas to detailed scientific models. This understanding underpins much of modern chemistry. (a) Discuss the historical development of the concept of an atom, mentioning at least two key contributors. [5] (b) Compare and contrast the properties of an individual atom of an element with a macroscopic sample of that same element. [5]

The understanding of atomic structure has evolved through a series of groundbreaking experiments. (a) Analyse how the results of the Rutherford gold foil experiment contradicted Thomson's 'plum pudding' model of the atom. [6] (b) Discuss the evidence that led to the discovery of the neutron. [5]

Elements are the fundamental substances from which all other matter is formed. Their unique characteristics stem from the atoms they are composed of. (a) Explain why atoms are considered the building blocks of matter. [3] (b) Describe how elements are represented in chemical notation, using a specific example. [4]

Lithium is an alkali metal with atomic number 3. Its most common isotope is lithium-7. (a) Sketch a simple diagram of a neutral atom of lithium-7, showing the nucleus and electron shells. Indicate the number of protons, neutrons, and electrons clearly. [4] (b) Explain why your diagram correctly represents a neutral atom of lithium-7. [3]

The concept of elements is fundamental to chemistry, describing the basic building blocks of matter. (a) Outline the definition of an element in terms of its atoms. [3] (b) Deduce why all atoms of a specific element have identical chemical properties. [3]

An unknown element forms an ion with a specific composition of subatomic particles. (a) Deduce the full symbol (including mass number and atomic number) for an ion with 19 protons, 20 neutrons, and 18 electrons. [4] (b) Show how the charge of the ion in (a) is determined from the number of protons and electrons. [3]

Lithium is an alkali metal. A neutral atom of lithium can be represented as 7 3Li. (a) Draw a simple diagram representing a neutral atom of 7 3Li, showing the nucleus and electron shells. [4] (b) Label the protons and neutrons in your diagram. [2] (c) Explain why the overall charge of this atom is neutral. [2]

Iron is an important metal, and its ions play a vital role in biology. (a) Calculate the number of protons, neutrons, and electrons in the ion 56 26Fe3+. [4] (b) Deduce the symbol for an atom with 15 protons, 16 neutrons, and 15 electrons. [4]

Silver is a transition metal with various applications, including in jewellery and electronics. One common isotope of silver is represented as 107 47Ag. (a) Calculate the number of protons, neutrons, and electrons in an atom of 107 47Ag. [4] (b) Explain how the atomic number and mass number are used to determine the number of neutrons. [3] (c) Deduce the number of electrons in the Ag+ ion. [2]

Chlorine is a common element with the symbol 35 17Cl. (a) State the atomic number and mass number for an atom of 35 17Cl. [2] (b) Determine the number of protons, neutrons, and electrons in a neutral atom of 35 17Cl. [3]

The identity and properties of an atom are determined by its subatomic particles. (a) Discuss the relationship between the atomic number, mass number, and the number of protons, neutrons, and electrons in a neutral atom. [6] (b) Deduce the subatomic particle composition of the ion formed by bromine (atomic number 35) when it gains one electron. [4]

The symbol for an atom or ion provides information about its subatomic particle composition. (a) Determine the number of protons, neutrons, and electrons in a neutral atom of 40 20Ca. [3] (b) Explain how the number of electrons changes when 40 20Ca forms a 2+ ion. [3]

Beryllium is a light metal used in alloys and as a neutron moderator. Consider a neutral atom of beryllium (atomic number 4, mass number 9). (a) Sketch a diagram of a beryllium atom, indicating the number of protons, neutrons, and electrons in their correct locations. [4] (b) Indicate the charge of the nucleus in your diagram. [2]

Fig 1.4 shows a cathode-ray tube setup with an electron beam passing through an electric field. a) State the direction of the electron beam's deflection when passing through the electric field in Fig 1.4. b) Explain how the charge of the electron and the polarity of the plates lead to the observed deflection, referring to the labels +10V and -10V. c) Suggest a change to the electric field (e.g., voltage) that would halve the initial deflection from 2.0 cm to 1.0 cm, and calculate the new voltage required.

Fig 1.2 shows the chemical symbol for a sodium atom. a) Determine the number of protons in the atom represented by the symbol shown. b) State the number of electrons in a neutral atom represented by the symbol shown. c) Calculate the number of neutrons in the atom represented by the symbol shown, using the mass number and atomic number.

Fig 1.4 shows a cathode-ray tube setup where an electron beam is deflected by an electric field. (a) Describe the setup of the electric field that causes the electron beam to deflect downwards, referring to the polarities of the plates. [2] (b) Explain the interaction between the electron beam and the electric field that results in the observed deflection, referencing the electron's charge. [3] (c) Predict the new deflection if the voltage across the plates is reduced from 8.0 V to 4.0 V, assuming an initial deflection of 3.0 cm for 8.0 V, and calculate this new deflection. Assume deflection is directly proportional to voltage. [5]

Fig 1.3 shows a simple model of a nitrogen atom. a) State the atomic number and mass number of the atom based on the diagram. b) Calculate the ratio of protons to neutrons in the nucleus of the atom shown. c) Identify the element represented by this atom, given its atomic number.

Fig 1.4 shows a simple model of a carbon atom and a table of relative charges and masses for subatomic particles. (a) Compare the charge of a proton and an electron, referring to the provided relative charge values. (b) Deduce the overall charge of the nucleus of the atom shown in Fig 1.4. (c) Calculate the total relative mass of the nucleons in the atom shown in Fig 1.4, given that the relative mass of a proton is 1 and a neutron is 1.

Fig 1.2 shows the chemical symbol for an atom of arsenic. a) Determine the number of protons and neutrons in the atom represented by the symbol ⁷⁵₃₃As. b) Explain how the number of electrons would change if this atom formed a 3- ion, and state the new number of electrons. c) Calculate the total relative charge of the ion ⁷⁵₃₃As³⁻, given the atomic number and the charge, and compare it to the charge of a single electron.

Fig 1.4 shows the chemical symbol for an atom of chlorine. a) Determine the number of protons and the mass number of the atom from the symbol ³⁵₁₇Cl. b) Explain how the mass number is derived from the subatomic particles in the nucleus. c) Calculate the number of neutrons in two different isotopes of chlorine: ³⁵₁₇Cl and ³⁷₁₇Cl, and state the difference in their neutron count.

Fig 1.3 shows a simple model of a beryllium atom. a) Identify the total number of subatomic particles in the nucleus of the atom shown. b) Compare the number of protons and neutrons in the nucleus shown. c) Calculate the total number of electrons required for this atom to be electrically neutral, considering the number of protons shown.

Fig 1.2 shows the chemical symbol for an atom of Calcium. (a) State the atomic number of the element shown. (b) Calculate the number of neutrons in the atom shown. (c) Identify the number of electrons in a neutral atom of this element.

Fig 1.1 shows the chemical symbol for a chromium ion. ⁵²₂₄Cr²⁺ (a) Deduce the number of protons and neutrons in this ion. [2] (b) Calculate the number of electrons in this ion, given its charge and proton count. [3] (c) Predict how the deflection of this ion would compare to an electron in an electric field of 5.0 V/cm, given the ion's charge and relative mass (mass of Cr is 52, electron mass is 1/1836), and explain the reasoning. [5]