RIDDLES — INTRODUCTION TO CHEMISTRY, SCIENTIFIC METHOD AND ATOMS
Chemistry & Its Branches
Riddle 1: I am a scientific discipline, not a single substance. I focus on the study of matter, its composition, structure and properties. I intersect with fields like physics, biology and environmental science. I am often described as central to understanding the natural world. Who am I?
ANSWER: Chemistry
Riddle 2: I am a branch of pure chemistry, not applied chemistry. I combine principles from physics and chemistry. I study the relationship between the physical properties of matter and its chemical composition and behaviour. I am one of three branches listed under pure chemistry, alongside organic and inorganic chemistry. Who am I?
ANSWER: Physical Chemistry
Riddle 3: I am a branch of pure chemistry. I study carbon-based molecules. I study their properties, composition and reactions. I am distinct from the branch of chemistry that studies non-carbon-based compounds. Who am I?
ANSWER: Organic Chemistry
Riddle 4: I am a branch of pure chemistry. I study non-carbon-based compounds. I include the study of the properties of elements, their compounds and their behaviours in different conditions. I am distinct from the branch of chemistry that studies carbon-based molecules. Who am I?
ANSWER: Inorganic Chemistry
Riddle 5: I am the study of basic principles and theories of chemistry, not their practical use. I involve exploring the properties, structure and behaviour of matter at a molecular and atomic level. Physical, organic and inorganic chemistry are all branches of me. I am distinct from the branch of chemistry focused on real-world applications. Who am I?
ANSWER: Pure Chemistry
Riddle 6: I am the branch of chemistry that studies the practical applications of chemical knowledge. I focus on solving real-world problems using scientific methods. I have diverse applications in food science, medicine, pharmaceuticals and agriculture. I am distinct from the branch of chemistry that studies principles without considering practical use. Who am I?
ANSWER: Applied Chemistry
Chemical Hazards
Riddle 7: I am a type of chemical hazard. I can rapidly release energy in the form of heat, light, gas and sound. Dynamite and ammonium nitrate are examples of substances like me. My release of energy can cause physical damage and injury. Who am I?
ANSWER: Explosives
Riddle 8: I am a type of chemical hazard. I can ignite or explode when exposed to heat, sparks or flames. Gasoline, propane and cooking oils are examples of substances like me. I can cause burns, fires and explosions. Who am I?
ANSWER: Flammable liquids and gases
Riddle 9: I am a type of chemical hazard. I can destroy or damage materials such as metals, plastics or human tissue. Hydrochloric acid and sodium hydroxide are examples of substances like me. I can cause severe burns and tissue damage. Who am I?
ANSWER: Corrosive substances
Riddle 10: I am a type of chemical hazard. I can harm or kill living organisms by interfering with biological functions. Arsenic, lead and cyanide are examples of substances like me. I disrupt vital organ systems. Who am I?
ANSWER: Toxic substances
Riddle 11: I am a type of chemical hazard. I can accelerate and promote combustion in other materials by providing oxygen or other oxidising agents. Hydrogen peroxide and potassium permanganate are examples of substances like me. I can cause severe burns, respiratory damage and explosions. Who am I?
ANSWER: Oxidising substances
Riddle 12: I am a type of chemical hazard. I spontaneously emit radiation as a result of the decay of atomic nuclei. Uranium and cobalt-60 are examples of substances like me. Proper handling and disposal of me are essential due to the risk of radiation exposure. Who am I?
ANSWER: Radioactive substances
Riddle 13: I am a type of chemical hazard. I can cause irritation or inflammation when I come into contact with the skin, eyes or respiratory system. Ammonia and detergents are examples of substances like me. I can cause itching, pain, redness, swelling and blistering. Who am I?
ANSWER: Irritant substances
Riddle 14: I am a type of chemical hazard. I can pose a risk to health and safety, causing acute or chronic effects depending on dose and duration. Lead, asbestos and tobacco smoke are examples of substances like me. My effects depend on the dose, duration and mode of exposure. Who am I?
ANSWER: Harmful substances
Riddle 15: I am a type of chemical hazard. I can pose a threat to the health and safety of living organisms. I may contain living and non-living biological agents such as bacteria, viruses and toxins. Blood, bodily fluids and microorganisms are examples of substances like me. Who am I?
ANSWER: Biohazard substances
Safety Equipment
Riddle 16: I am a safety device, not a chemical. I am designed to extinguish incipient, or starting, fires. To use me, you should hold my corner and cover the fire starting from its base. I should stay in place until the fire has completely stopped. Who am I?
ANSWER: A fire blanket
Riddle 17: I am a handheld active fire protection device, not a fixed blanket. I am usually filled with a dry or wet chemical. To use me, you aim at the base of the flames and squeeze the handle. The acronym PASS describes the steps for using me: Pull, Aim, Squeeze, Sweep. Who am I?
ANSWER: A fire extinguisher
Riddle 18: I am gear worn to protect a person from hazards, not a piece of lab equipment. Respirators, hand gloves, eye protectors and protective clothing are all examples of me. I am designed to protect the wearer from injury, illness or death. A lab coat and safety goggles are both common examples of me in a chemistry laboratory. Who am I?
ANSWER: Personal Protective Equipment (PPE)
Riddle 19: I am a safety device, not a piece of protective clothing. I am found in workplaces where hazardous exposure is possible. I provide immediate treatment to someone who has had contact with hazardous materials in the eye. I consist of a basin attached to a water supply. Who am I?
ANSWER: Eye shower station
Riddle 20: I am an enclosed space or hood, not an open bench. I am designed to contain and capture hazardous fumes, dust or vapours. I protect workers from dangerous substances that may be emitted during experiments. I also help prevent contamination of the external environment. Who am I?
ANSWER: Fume chamber (fume hood)
Scientific Method & Related Concepts
Riddle 21: I am a systematic approach, not a single experiment. I am used to investigate and learn about the natural world in a logical, objective and repeatable manner. Making observations, formulating a question and developing a hypothesis are among my early steps. Communicating results is my final step. Who am I?
ANSWER: The scientific method
Riddle 22: I am a testable explanation, not a proven fact. I am designed to guide experimentation and the checking of information. I am also described as an educated guess about the answer to a question. I am formed after observations have been made and a question has been asked. Who am I?
ANSWER: A hypothesis
Riddle 23: I am a well-established explanation, not a mere guess. I am based on experimental data. Unlike a hypothesis, I have already been extensively tested and supported by evidence. I represent a more advanced stage of scientific understanding than an untested hypothesis. Who am I?
ANSWER: A scientific theory
Riddle 24: I am a relationship between physical observables, not an explanation of why something happens. I am often represented by a mathematical formula. I am tested and developed using numerous and diverse experimental observations. Unlike a theory, I describe what happens rather than explaining the underlying cause. Who am I?
ANSWER: A scientific law
Dalton & Atomic Theory
Riddle 25: I am an idea, not a single experiment. I state that elements are made up of atoms. Several scientists contributed to my modern form, including Dalton, Thomson and Rutherford. My development spans centuries of scientific discovery about the structure of matter. Who am I?
ANSWER: Atomic theory
Riddle 26: I am a set of postulates, not a single experiment. I state that all elements are made up of small, indivisible particles. I also state that atoms of the same element are identical, while atoms of different elements differ. Some of my postulates have since been modified by later discoveries, such as isotopes. Who am I?
ANSWER: Dalton's atomic theory
Riddle 27: I am not a single atom, but a relationship between atoms. Atoms described by this term share the same number of protons but have different numbers of neutrons. A carbon atom, for instance, can have 6, 7 or 8 neutrons while remaining an example of me. My existence contradicts one of Dalton's original postulates. Who am I?
ANSWER: Isotopes
J.J. Thomson
Riddle 28: I am a series of experiments, not a single observation. I involved passing an electric current through a vacuum tube. I revealed a stream of negatively charged particles travelling from the cathode to the anode. I laid the foundation for the discovery of the electron. Who am I?
ANSWER: The cathode ray experiment
Riddle 29: I am a subatomic particle, not a whole atom. I was discovered by studying the particles that made up cathode rays. My charge-to-mass ratio was found to be much smaller than any known atom. I carry a negative charge and am located outside the nucleus. Who am I?
ANSWER: Electron
Riddle 30: I am a model of the atom, not the atom itself. I was developed based on the discovery of the electron. I describe the atom as a positively charged sphere with negatively charged particles embedded within it, like plums in a pudding. I was later disproved by the discovery of the atomic nucleus. Who am I?
ANSWER: The plum pudding model
Rutherford
Riddle 31: I am a landmark experiment, not a theory. I involved firing positively charged alpha particles at a thin sheet of gold foil. Most particles passed straight through, but some were scattered at very large angles, and a few even bounced backward. My results provided evidence for the existence of the atomic nucleus. Who am I?
ANSWER: The gold foil (alpha scattering) experiment
Riddle 32: I am a model of the atom, not the experiment that produced the evidence for it. I introduced the concept of a small, dense, positively charged nucleus at the centre of the atom. Electrons orbit around me in specific paths, similar to planets orbiting the sun. I was unable to explain why electrons don't eventually spiral into the nucleus. Who am I?
ANSWER: Rutherford's nuclear model
Riddle 33: I am a structure, not a whole atom. I am small, dense and positively charged. I contain most of the mass of the atom. I am surrounded by negatively charged electrons. Who am I?
ANSWER: The atomic nucleus
Subatomic Particles
Riddle 34: I am a subatomic particle, not an entire nucleus. I carry a positive charge. My relative mass is 1 atomic mass unit. I am found within the nucleus of an atom, alongside the neutron. Who am I?
ANSWER: Proton
Riddle 35: I am a subatomic particle, not an entire nucleus. I carry no charge at all. My relative mass is 1 atomic mass unit, the same as the proton. I am found within the nucleus of an atom. Who am I?
ANSWER: Neutron
Bohr's Theory
Riddle 36: I am a theory of the atom, not a single experiment. I state that electrons orbit the nucleus in fixed, circular orbits at specific energy levels. These energy levels are quantised, meaning electrons can only occupy specific states. I introduced the concepts of ground state and excited state. Who am I?
ANSWER: Bohr's planetary theory
Riddle 37: I am a condition of an electron, not a whole atom. I describe an electron orbiting the nucleus at its lowest possible energy level. An electron only leaves me by absorbing energy. I am the opposite of an excited state, where an electron has jumped to a higher energy level. Who am I?
ANSWER: Ground state
Riddle 38: I am a condition of an electron, not a whole atom. I describe an electron that has absorbed energy and jumped to a higher energy level. An electron eventually returns from me to its ground state, releasing energy in the process. The energy released as an electron leaves me corresponds to a specific wavelength of light. Who am I?
ANSWER: Excited state
Riddle 39: I am a spectrum of electromagnetic radiation, not a set of discrete lines. I contain photons of all energy levels within a specific range. A hot solid object, such as a light bulb filament, is an example of a source that produces me. I appear as a smooth display of colours or wavelengths. Who am I?
ANSWER: Continuous spectrum
Riddle 40: I am a spectrum produced by an excited atom or molecule, not a hot solid object. I contain only discrete wavelengths or colours of electromagnetic radiation. I appear as a series of coloured lines or bands, rather than a smooth display. Each chemical element has its own unique version of me. Who am I?
ANSWER: Line spectrum
Quantum Theory
Riddle 41: I am a concept, not a physical object. I suggest that particles can exhibit both wave-like and particle-like behaviours. Quantum theory introduced me to help explain the behaviour of electrons in atoms. Electrons exhibit both a particle-like and a wave-like nature because of me. Who am I?
ANSWER: Wave-particle duality
Riddle 42: I am a principle, not a physical particle. I state that it is impossible to know both the position and the momentum of an electron at the same time. Quantum theory introduced me to describe the limits of measurement at the atomic scale. I place a fundamental limit on how precisely certain pairs of properties can be known simultaneously. Who am I?
ANSWER: The uncertainty principle
Riddle 43: I am a type of quantum number, not a physical particle. I determine the energy level of an electron. I describe the size of the electron cloud. I can have any positive value starting from 1. Who am I?
ANSWER: Principal quantum number (n)
Riddle 44: I am a type of quantum number, not a physical particle. I indicate the shape of the electron cloud, or the subshell in which an electron is present. I can have a value from 0 to one less than the principal quantum number. Who am I?
ANSWER: Angular momentum (azimuthal) quantum number (l)
Riddle 45: I am a type of quantum number, not a physical particle. I specify the orientation of the electron cloud in space. I can have values ranging from negative to positive versions of the angular momentum quantum number. Who am I?
ANSWER: Magnetic quantum number (m)
Riddle 46: I am a type of quantum number, not a physical particle. I describe the spin of an electron, a fundamental property of all particles. I can only have one of two possible values, positive or negative one-half. Who am I?
ANSWER: Spin quantum number (s)
Riddle 47: I am a type of orbital, not a whole subshell of multiple shapes. I am the lowest orbital. I have a spherical shape. I can hold up to two electrons. Who am I?
ANSWER: The s orbital
Riddle 48: I am a type of orbital, not a subshell with only one shape. I have a dumb-bell shape. I come in three versions, aligned along perpendicular axes. Together, versions of me can hold up to six electrons. Who am I?
ANSWER: The p orbital(s)
Riddle 49: I am a type of orbital, not the simplest kind. I have more complex shapes than the s and p orbitals. I am found in the third energy level and higher. Together, versions of me can hold up to ten electrons in total. Who am I?
ANSWER: The d orbital(s)
Electron Filling Rules
Riddle 50: I am a fundamental principle in chemistry, also known as the building-up principle. I state that atomic orbitals are filled with electrons in order of increasing energy. Electrons fill lower energy orbitals before moving on to higher energy levels under me. I am used to determine the electron configuration of atoms. Who am I?
ANSWER: Aufbau's principle
Riddle 51: I am a fundamental principle in quantum mechanics, not a rule about orbital shapes. I state that no two electrons in an atom can have the same set of quantum numbers. If two electrons share an orbital, I require them to have opposite spins. I limit the number of electrons that can occupy any single orbital. Who am I?
ANSWER: Pauli's exclusion principle
Riddle 52: I am a principle in quantum mechanics, not a rule about the order orbitals are filled in. I state that electrons will occupy orbitals singly, with parallel spins, before they pair up. Electron pairing in p and d orbitals cannot occur until each orbital in the subshell holds one electron. Who am I?
ANSWER: Hund's rule of maximum multiplicity
Mass Concepts
Riddle 53: I am a value, not a physical object. I am the average mass of an atom of an element, considering all its naturally occurring isotopes. I am measured relative to the mass of a carbon-12 atom, which is assigned a mass of exactly 12. My value is determined by the abundance of each isotope of an element. Who am I?
ANSWER: Relative atomic mass
Riddle 54: I am a value, not a physical object. I am the sum of the relative atomic masses of all the atoms in a molecule. I am also measured relative to the mass of carbon-12. I am calculated by adding up the atomic masses of every atom present in a molecule. Who am I?
ANSWER: Relative molecular mass
Riddle 55: I am an instrument, not a value. I am used for measuring the mass-to-charge ratio of ions in a sample. I generate ions from a sample, then separate them using electric and magnetic fields. I am used in fields such as chemistry, biochemistry and environmental science. Who am I?
ANSWER: A mass spectrometer
Riddle 56: I am a graphical representation, not the instrument that produces it. I show ion intensities, or relative abundances, as a function of their mass-to-charge ratios. I show a series of peaks, each representing an ion with a specific mass-to-charge ratio. The height of each peak in me is proportional to the abundance of that ion. Who am I?
ANSWER: A mass spectrum
Radioactivity
Riddle 57: I am a process, not a single particle. I involve the emission of energy from an unstable nucleus, either as particles or electromagnetic radiation. I have practical applications in medicine, industry and energy production. I also pose health risks that require careful management. Who am I?
ANSWER: Radioactivity
Riddle 58: I am not a stable form of an element, but an unstable one. I am also referred to as a radionuclide. I decay at a fixed rate, characterised by a half-life. My rate of decay is unique to each individual version of me. Who am I?
ANSWER: A radioisotope
Riddle 59: I am a length of time, not a physical substance. I am the time taken for half of the unstable nuclei in a sample to decay. I am also described as the time taken for the activity of a radioactive substance to reduce to half of its original value. My value is a fixed, characteristic property of each radioactive nuclide. Who am I?
ANSWER: Half-life
Riddle 60: I am a type of ionising radiation, not the whole process of radioactivity. I consist of a helium nucleus, made of two protons and two neutrons. I have a charge of positive two. I can be blocked by a sheet of paper or the dead cells on the surface of skin. Who am I?
ANSWER: Alpha radiation
Riddle 61: I am a type of ionising radiation, not the whole process of radioactivity. I consist of a negatively charged particle identical to a high-energy electron. I have a charge of negative one and a negligible mass. I am more penetrating than alpha particles, able to pass through several millimetres of aluminium. Who am I?
ANSWER: Beta radiation
Riddle 62: I am a type of ionising radiation, not the whole process of radioactivity. I consist of high-energy photons of electromagnetic radiation. I have no charge and no mass. I am highly penetrating, able to pass through several centimetres of lead or concrete. Who am I?
ANSWER: Gamma radiation
Riddle 63: I am a ratio, not a fixed number for every nucleus. I describe the balance between the number of neutrons and the number of protons in a nucleus. When I am too low or too high, the resulting nucleus tends to be unstable. For light isotopes, a stable version of me tends to be close to one. Who am I?
ANSWER: Neutron-to-proton ratio
Riddle 64: I am a measure of energy, not a measure of mass alone. I refer to the average amount of energy required to remove a nucleon from the nucleus of an atom. I am calculated by dividing the total binding energy of a nucleus by its total number of nucleons. A high value of me generally indicates a more stable nucleus. Who am I?
ANSWER: Binding energy per nucleon
Riddle 65: I am a type of reaction, not a chemical one. I involve changes in the atomic nuclei of the reacting substances. I result in the formation of different nuclei and subatomic particles. I involve much larger energy changes than a chemical reaction. Who am I?
ANSWER: A nuclear reaction
Uses & Risks of Radioactivity
Riddle 66: I am a use of radioisotopes, not a use of ordinary chemicals. Technetium-99, iodine-131 and gallium-67 are examples of radioisotopes used for me. Techniques like PET, SPECT and CT scans rely on radioisotopes emitting gamma rays that special cameras can detect. I allow doctors to diagnose and monitor diseases such as cancer and heart disease. Who am I?
ANSWER: Medical diagnosis (using radioisotopes)
Riddle 67: I am a use of radioisotopes, not a use of ordinary chemicals. I involve selectively targeting and destroying cancerous cells. Iodine-131 is used for me in treating thyroid cancer, while strontium-89 relieves pain in bone cancer patients. I differ from diagnostic uses of radioisotopes, since my goal is destruction of diseased tissue rather than imaging. Who am I?
ANSWER: Medical treatment (using radioisotopes)
Riddle 68: I am a use of radioisotopes, not a use of ordinary chemicals. Cobalt-60 and iridium-192 are examples of radioisotopes used for me. I include sterilising medical equipment and food products. I also include measuring the thickness of materials during manufacturing. Who am I?
ANSWER: Industrial applications (of radioisotopes)
Riddle 69: I am a use of radioisotopes, not a use of ordinary chemicals. I involve measuring plant and soil properties, such as moisture content and nutrient uptake. I help improve crop yield and quality. Radioisotopes used for me are also applied in insect and pest control. Who am I?
ANSWER: Agricultural applications (of radioisotopes)
Riddle 70: I am a risk associated with radioactivity, not a benefit of it. I can damage the DNA in cells, leading to cellular mutations and cancer. Long-term exposure to low levels of me is associated with an increased risk of cancer. High levels of me can cause sickness and death. Who am I?
ANSWER: Radiation exposure