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24:[["$","$L33",null,{"feature":"flashcards"}],"$L34",["$","$L35",null,{"href":"/igcse/chemistry/cie/isotopes/flashcards","label":"Isotopes","subjectCode":"igcse_chemistry__cie","surface":"flashcards"}],["$","$L36",null,{"runner":["$","div",null,{"className":"min-h-0 flex-1 overflow-hidden bg-background","children":["$","$L37",null,{"decks":[{"id":"144fcb54-e53b-4f1f-9a64-80dda30787b8","title":"Isotopes Flashcards","topicId":"24439df0-f327-52b4-a100-8d698bcbc607","topicSlug":"isotopes","cards":[{"id":"08c42a88-d974-4e12-bc6d-ffff2999f0d9","cardType":"basic","points":1,"front":"What subatomic particle determines which element an atom belongs to?","back":"Protons","mcqOptions":[{"text":"Protons","correct":true,"explanation":"The number of protons is the proton number, which identifies the element. Every atom of the same element has the same number of protons, even if its electrons or neutrons differ."},{"text":"Electrons","correct":false,"explanation":"Electrons can be gained or lost when ions form, so their number does not identify the element. The correct particle is protons, whose number remains fixed for each element."},{"text":"Neutrons","correct":false,"explanation":"Neutrons can vary between isotopes of the same element, so they do not determine elemental identity. The element is determined by its number of protons."},{"text":"Nucleus","correct":false,"explanation":"The nucleus contains protons and neutrons, but it is not itself a subatomic particle that determines the element. The number of protons in the nucleus gives the element’s identity."}]},{"id":"b038f5ba-c0f9-4b89-95cf-8347d6d31e04","cardType":"cloze","points":null,"front":"The [ ] is the number of protons in a nucleus, while the nucleon number is the total number of protons and neutrons.","back":"The proton number is the number of protons in a nucleus, while the nucleon number is the total number of protons and neutrons.","mcqOptions":[{"text":"proton number","correct":true,"explanation":"The proton number is defined as the number of protons in the nucleus. It identifies the element, whereas the nucleon number counts both protons and neutrons."},{"text":"nucleon number","correct":false,"explanation":"The nucleon number is the total number of protons and neutrons, so it belongs in the second part of the sentence. The number of protons is the proton number."},{"text":"electron number","correct":false,"explanation":"Electron number describes the electrons in an atom or ion and does not define the nucleus. The quantity counting protons is called the proton number."},{"text":"neutron number","correct":false,"explanation":"Neutron number counts only neutrons, not protons. The term for the number of protons in a nucleus is proton number, while protons plus neutrons give nucleon number."}]},{"id":"b99181dd-a31c-4fb1-ae9a-436ecf520d39","cardType":"cloze","points":null,"front":"The proton number is the number of protons in a nucleus, while the [ ] is the total number of protons and neutrons.","back":"The proton number is the number of protons in a nucleus, while the nucleon number is the total number of protons and neutrons.","mcqOptions":[{"text":"nucleon number","correct":true,"explanation":"The nucleon number is the total number of protons and neutrons in the nucleus. It is also called the mass number, but proton number counts protons only."},{"text":"proton number","correct":false,"explanation":"Proton number counts only the protons and is already defined in the first part of the sentence. The total of protons and neutrons is the nucleon number."},{"text":"neutron number","correct":false,"explanation":"Neutron number counts only the neutrons, so it does not represent all particles in the nucleus. The total number of protons and neutrons is the nucleon number."},{"text":"atomic number","correct":false,"explanation":"Atomic number is another name for proton number, not the total number of nucleons. The total of protons and neutrons is called the nucleon number."}]},{"id":"0c9bd83d-f114-4c0a-9148-b74d26122756","cardType":"basic","points":1,"front":"How is the number of neutrons in an atom calculated using the nucleon number ($A$) and proton number ($Z$)?","back":"$$$A - Z$$","mcqOptions":[{"text":"$$$A - Z$$","correct":true,"explanation":"The nucleon number A counts protons and neutrons, while the proton number Z counts protons. Subtracting Z from A therefore leaves the number of neutrons."},{"text":"$$$A + Z$$","correct":false,"explanation":"Adding A and Z counts the proton number twice rather than removing the protons from the total. The correct calculation is A - Z to find neutrons."},{"text":"$$$Z - A$$","correct":false,"explanation":"Reversing the subtraction usually produces a negative value because A is at least as large as Z. Neutrons are found by subtracting proton number Z from nucleon number A."},{"text":"$$$\\frac{A}{Z}$$","correct":false,"explanation":"Dividing the nucleon number by the proton number gives a ratio, not the number of neutrons. Subtracting Z from A removes the protons from the nucleon total."}]},{"id":"c6d1759f-8d8b-490d-a5b1-2664132664dc","cardType":"basic","points":2,"front":"Identify the number of protons and neutrons in ${}^{23}_{11}Na$.","back":"

Protons: 11
Neutrons: 12

","mcqOptions":[{"text":"

Protons: 11
Neutrons: 12

","correct":true,"explanation":"The lower number, 11, is the proton number, so there are 11 protons. The neutron number is 23 - 11 = 12."},{"text":"

Protons: 12
Neutrons: 11

","correct":false,"explanation":"This swaps the roles of the proton and neutron numbers. The lower number gives 11 protons, and subtracting it from 23 gives 12 neutrons."},{"text":"

Protons: 11
Neutrons: 23

","correct":false,"explanation":"The nucleon number 23 represents protons plus neutrons, not neutrons alone. There are 11 protons, so the neutron number is 23 - 11 = 12."},{"text":"

Protons: 23
Neutrons: 11

","correct":false,"explanation":"The upper number is the total number of nucleons, not the proton number. Sodium has 11 protons, and its 12 neutrons come from 23 - 11."}]},{"id":"f78a3c6e-79db-4ae0-83d9-faddefd29985","cardType":"basic","points":1,"front":"What specific subatomic particle change occurs when an atom becomes a positive ion?","back":"It loses electrons.","mcqOptions":[{"text":"It loses electrons.","correct":true,"explanation":"Electrons have negative charge, so losing electrons leaves more positive charge than negative charge. The atom therefore becomes a positive ion without changing its proton number."},{"text":"It gains electrons.","correct":false,"explanation":"Gaining negatively charged electrons makes an atom more negative, forming a negative ion. A positive ion forms when the atom loses electrons."},{"text":"It loses protons.","correct":false,"explanation":"Protons are held in the nucleus and their number determines the element, so losing one would change the element rather than simply form an ion. Positive ions lose electrons."},{"text":"It gains neutrons.","correct":false,"explanation":"Gaining neutrons changes the isotope and does not give the atom a positive charge. Positive charge results from losing negatively charged electrons."}]},{"id":"a1688c44-2508-4bd2-95af-3e45f3237987","cardType":"cloze","points":null,"front":"When an ion forms, the number of [ ] never changes; only the number of electrons is altered.","back":"When an ion forms, the number of protons never changes; only the number of electrons is altered.","mcqOptions":[{"text":"protons","correct":true,"explanation":"Ion formation changes only the number of electrons. The number of protons stays constant because changing it would produce a different element, not an ion of the same element."},{"text":"neutrons","correct":false,"explanation":"Changing the number of neutrons creates a different isotope, not an ion. During ion formation, the number of protons remains unchanged and only electrons are gained or lost."},{"text":"electrons","correct":false,"explanation":"Electrons are precisely the particles whose number changes when an ion forms. The unchanged particles in the nucleus include the protons, which identify the element."},{"text":"nuclei","correct":false,"explanation":"Ion formation does not involve changing the number of nuclei; it changes the electron arrangement of an atom. The number of protons remains constant."}]},{"id":"5f65747f-1649-4a0e-8c18-ebf7955580f1","cardType":"cloze","points":null,"front":"When an ion forms, the number of protons never changes; only the number of [ ] is altered.","back":"When an ion forms, the number of protons never changes; only the number of electrons is altered.","mcqOptions":[{"text":"electrons","correct":true,"explanation":"Ion formation involves gaining or losing electrons, which changes the atom’s charge. The proton number remains unchanged, so the element itself does not change."},{"text":"protons","correct":false,"explanation":"Protons do not change when an ion forms because they determine the element’s identity. The particle whose number is altered is the electron."},{"text":"neutrons","correct":false,"explanation":"Changing neutron number produces an isotope rather than an ion. Ions form when electrons are gained or lost, while both protons and neutrons remain unchanged."},{"text":"nucleons","correct":false,"explanation":"Nucleons are protons and neutrons, and their number is not altered during ion formation. Only electrons change in number, producing the ion’s charge."}]},{"id":"2f69ced3-92d6-4337-8957-aa78752be1df","cardType":"basic","points":2,"front":"Calculate the number of protons and electrons in the ion ${}^{35}_{17}Cl^{-}$.","back":"

Protons: 17
Electrons: 18

","mcqOptions":[{"text":"

Protons: 17
Electrons: 18

","correct":true,"explanation":"The atomic number gives 17 protons. A 1− charge means the ion has gained one electron, so it contains 18 electrons."},{"text":"

Protons: 18
Electrons: 17

","correct":false,"explanation":"The numbers have been reversed and the charge has been interpreted incorrectly. Chlorine’s atomic number gives 17 protons, while its 1− charge gives it 18 electrons."},{"text":"

Protons: 17
Electrons: 16

","correct":false,"explanation":"A 1− ion gains an electron rather than losing one. Chlorine has 17 protons, so this ion contains 18 electrons, not 16."},{"text":"

Protons: 18
Electrons: 18

","correct":false,"explanation":"The atomic number is 17, so the ion cannot have 18 protons. The negative charge adds one electron, giving 17 protons and 18 electrons."}]},{"id":"f912a2eb-88b8-4139-ac37-934af1116685","cardType":"basic","points":2,"front":"Define isotopes in terms of subatomic particles.","back":"Atoms with the same number of protons but different numbers of neutrons.","mcqOptions":[{"text":"Atoms with the same number of protons but different numbers of neutrons.","correct":true,"explanation":"Isotopes are atoms of the same element, so they must have the same number of protons, but they differ in their numbers of neutrons."},{"text":"Atoms with different numbers of protons but the same number of neutrons.","correct":false,"explanation":"Changing the number of protons changes the element itself. Isotopes instead have the same number of protons and different numbers of neutrons."},{"text":"Atoms with the same number of neutrons but different numbers of electrons.","correct":false,"explanation":"Electron differences describe ions, not isotopes. Isotopes are atoms with the same number of protons but different numbers of neutrons."},{"text":"Atoms with different numbers of protons but different numbers of neutrons.","correct":false,"explanation":"Different proton numbers identify different elements, so this cannot define isotopes. Isotopes must share the same proton number and differ in neutron number."}]},{"id":"7ed6f73e-3cd4-4030-8b90-d1f38ef0b7a1","cardType":"cloze","points":null,"front":"Isotopes are atoms of the same element because they have the same [ ] number.","back":"Isotopes are atoms of the same element because they have the same proton number.","mcqOptions":[{"text":"proton","correct":true,"explanation":"The proton number, or atomic number, identifies an element. Isotopes have the same proton number, although their neutron numbers differ."},{"text":"neutron","correct":false,"explanation":"Neutron numbers can differ between isotopes, so they do not identify the element. Isotopes are defined by having the same proton number."},{"text":"electron","correct":false,"explanation":"Neutral atoms have equal proton and electron numbers, but electron numbers can change when ions form. The defining number for an element is its proton number."},{"text":"nucleon","correct":false,"explanation":"Nucleons include both protons and neutrons, so their total number can differ between isotopes. The shared number that identifies the element is the proton number."}]},{"id":"a157efba-48df-4b4a-9e8d-71ff0bd20d66","cardType":"basic","points":1,"front":"How does the nucleus of carbon-14 differ from the nucleus of carbon-12?","back":"It has two more neutrons.","mcqOptions":[{"text":"It has two more neutrons.","correct":true,"explanation":"Both nuclei have six protons because they are carbon atoms. Carbon-14 has 14 − 6 = 8 neutrons, whereas carbon-12 has 12 − 6 = 6."},{"text":"It has two more protons.","correct":false,"explanation":"The proton number defines the element, so both carbon nuclei contain six protons. The mass difference comes from carbon-14 having two more neutrons."},{"text":"It has two fewer neutrons.","correct":false,"explanation":"Carbon-14 has the larger mass number, so it contains more neutrons than carbon-12. Both have six protons, giving neutron numbers of eight and six respectively."},{"text":"It has two more electrons.","correct":false,"explanation":"The question compares nuclei, which contain protons and neutrons, not electrons. Carbon-14 differs from carbon-12 by having two additional neutrons."}]},{"id":"5b726ea0-0994-47e8-9ad1-18e1731f65df","cardType":"cloze","points":null,"front":"Chemical properties of isotopes are identical because they have the same [ ].","back":"Chemical properties of isotopes are identical because they have the same electronic configuration.","mcqOptions":[{"text":"electronic configuration","correct":true,"explanation":"Isotopes of an element have the same proton number and, as neutral atoms, the same electron arrangement. This gives them identical chemical behaviour."},{"text":"number of neutrons","correct":false,"explanation":"The neutron number differs between isotopes and mainly affects mass-related physical properties. Identical chemical properties result from their shared electronic configuration."},{"text":"mass number","correct":false,"explanation":"Mass number changes between isotopes because their neutron numbers differ. Chemical behaviour depends mainly on electron arrangement, which remains the same."},{"text":"nuclear charge","correct":false,"explanation":"Nuclear charge is related to the proton number and is shared by isotopes, but the expected property determining chemical behaviour is their electronic configuration."}]},{"id":"a84648db-96f4-4bd0-9e88-e235069e0306","cardType":"basic","points":2,"front":"Why do isotopes of the same element exhibit identical chemical properties?","back":"They have the same number of electrons and the same outer shell arrangement.","mcqOptions":[{"text":"They have the same number of electrons and the same outer shell arrangement.","correct":true,"explanation":"Neutral isotopes have the same proton number and therefore the same number of electrons. Their identical outer-shell arrangements control their chemical reactions."},{"text":"They have the same number of neutrons and the same outer shell arrangement.","correct":false,"explanation":"Isotopes differ in neutron number, not necessarily share it. Their chemical properties are identical because they have the same number of electrons and outer-shell arrangement."},{"text":"They have the same number of electrons and the same nuclear mass.","correct":false,"explanation":"The electron number is relevant, but nuclear mass differs because isotopes contain different numbers of neutrons. Chemical behaviour depends on electron arrangement, especially the outer shell."},{"text":"They have the same number of protons and the same number of neutrons.","correct":false,"explanation":"Isotopes do share the same proton number, but their neutron numbers are different by definition. Their identical chemical properties arise from the same electron arrangement."}]},{"id":"558e7ff2-1ea4-47b8-a294-e8ae37968865","cardType":"basic","points":1,"front":"Which properties of an element differ between its isotopes?","back":"Physical properties (such as mass).","mcqOptions":[{"text":"Physical properties (such as mass).","correct":true,"explanation":"Different neutron numbers give isotopes different masses and can affect physical properties such as density or melting point, while their chemical properties remain broadly identical."},{"text":"Chemical properties (such as reactivity).","correct":false,"explanation":"Chemical properties are largely determined by electron arrangement, which is the same in neutral isotopes. Isotopes mainly differ in physical properties because their masses differ."},{"text":"Atomic number (such as proton number).","correct":false,"explanation":"The atomic number is the proton number, which remains constant for all isotopes of an element. Isotopes differ chiefly in physical properties such as mass."},{"text":"Electron arrangement (such as outer shell structure).","correct":false,"explanation":"Neutral isotopes have the same electron arrangement, so this does not differ between them. Their different neutron numbers cause differences in physical properties such as mass."}]},{"id":"059fd6fa-ca05-4426-896e-af78d46c5899","cardType":"cloze","points":null,"front":"Relative atomic mass ($A_r$) is the weighted average mass of an element's atoms compared with one twelfth of the mass of a [ ] atom.","back":"Relative atomic mass ($A_r$) is the weighted average mass of an element's atoms compared with one twelfth of the mass of a carbon-12 atom.","mcqOptions":[{"text":"carbon-12","correct":true,"explanation":"Relative atomic mass is measured against one twelfth of the mass of a carbon-12 atom, the internationally agreed reference standard for atomic masses."},{"text":"carbon-14","correct":false,"explanation":"Carbon-14 is a radioactive isotope, but it is not the reference standard for relative atomic mass. The standard is one twelfth of the mass of carbon-12."},{"text":"oxygen-16","correct":false,"explanation":"Oxygen-16 was used in some older atomic-mass scales, but the modern reference is based on carbon-12. Relative atomic mass compares with one twelfth of carbon-12’s mass."},{"text":"hydrogen-1","correct":false,"explanation":"Hydrogen-1 is the lightest common isotope, but it is not the modern reference for relative atomic mass. The agreed standard is carbon-12."}]},{"id":"ba87124c-c9bb-4dcb-9cb7-6e1cc5fae91f","cardType":"basic","points":1,"front":"Why is the relative atomic mass ($A_r$) of chlorine listed as 35.5 rather than a whole number?","back":"It is a weighted average of its isotopes (chlorine-35 and chlorine-37).","mcqOptions":[{"text":"It is a weighted average of its isotopes (chlorine-35 and chlorine-37).","correct":true,"explanation":"Chlorine exists as chlorine-35 and chlorine-37 in different abundances, so its relative atomic mass is their abundance-weighted mean rather than the mass number of one isotope."},{"text":"It is the mass number of the most abundant isotope (chlorine-35).","correct":false,"explanation":"This confuses relative atomic mass with mass number. Chlorine-35 is the more abundant isotope, but the listed 35.5 is a weighted average of chlorine-35 and chlorine-37."},{"text":"It is the total number of protons and electrons in chlorine atoms.","correct":false,"explanation":"Atomic mass does not count electrons, and chlorine atoms have different neutron numbers in their isotopes. The correct value comes from weighting chlorine-35 and chlorine-37 by their abundances."},{"text":"It is the average of chlorine’s atomic number and mass number.","correct":false,"explanation":"Relative atomic mass is not found by averaging atomic number and mass number. It is calculated from the masses and percentage abundances of chlorine’s isotopes."}]},{"id":"2c4fbee6-6b56-44b5-9066-03cd9b2fe0eb","cardType":"basic","points":1,"front":"What is the formula for calculating $A_r$ using percentage abundances $a_1, a_2$ and isotope masses $m_1, m_2$?","back":"$$$\\frac{(m_1 \\times a_1) + (m_2 \\times a_2)}{100}$$","mcqOptions":[{"text":"$$$\\frac{(m_1 \\times a_1) + (m_2 \\times a_2)}{100}$$","correct":true,"explanation":"Each isotope mass is multiplied by its percentage abundance, the products are added, and the total is divided by 100 because the abundances are percentages."},{"text":"$$$\\frac{(m_1 + m_2) \\times (a_1 + a_2)}{100}$$","correct":false,"explanation":"This multiplies the combined mass by the combined abundance, ignoring each isotope’s separate contribution. The correct method multiplies each mass by its own percentage abundance before adding."},{"text":"$$$\\frac{(m_1 \\times m_2) + (a_1 \\times a_2)}{100}$$","correct":false,"explanation":"Masses should not be multiplied together, and abundances must weight their corresponding isotope masses. The correct formula uses $m_1a_1 + m_2a_2$, then divides by 100."},{"text":"$$$(m_1 \\times a_1) + (m_2 \\times a_2) \\times 100$$","correct":false,"explanation":"Multiplying by 100 instead of dividing by 100 makes the result far too large. Percentage abundances require division by 100 after the weighted products are added."}]},{"id":"3f591ccf-6a77-41ce-b383-40287fb9a428","cardType":"basic","points":1,"front":"Calculate the $A_r$ of chlorine if it is 75% chlorine-35 and 25% chlorine-37.","back":"35.5","mcqOptions":[{"text":"35.5","correct":true,"explanation":"The weighted average is $\\frac{(35 \\times 75) + (37 \\times 25)}{100} = 35.5$, so chlorine’s relative atomic mass is 35.5."},{"text":"35.0","correct":false,"explanation":"This uses only the more abundant chlorine-35 isotope and ignores chlorine-37. Including the 25% contribution from chlorine-37 raises the weighted average to 35.5."},{"text":"36.0","correct":false,"explanation":"This is the simple average of 35 and 37, which incorrectly treats both isotopes as equally abundant. Their 75% and 25% abundances give a weighted average of 35.5."},{"text":"36.5","correct":false,"explanation":"This overweights chlorine-37, as though it were the more abundant isotope. Applying the actual abundances gives $\\frac{2625 + 925}{100} = 35.5$."}]},{"id":"c4242aae-95e9-414d-82df-1c8facd8d605","cardType":"basic","points":1,"front":"If isotope abundances are given as a ratio of 1:4, what value is used as the divisor to calculate the $A_r$?","back":"5 (the total number of parts).","mcqOptions":[{"text":"5 (the total number of parts).","correct":true,"explanation":"A ratio of 1:4 contains $1 + 4 = 5$ total parts, so the weighted isotope-mass total must be divided by 5."},{"text":"4 (the number of parts for the more abundant isotope).","correct":false,"explanation":"Using 4 considers only the larger ratio part and omits the first isotope’s part. The divisor must be the total number of parts, $1 + 4 = 5$."},{"text":"1 (the number of parts for the less abundant isotope).","correct":false,"explanation":"The divisor is not one selected isotope’s share. Both ratio parts contribute, so the total divisor is $1 + 4 = 5$."},{"text":"10 (the ratio multiplied by two).","correct":false,"explanation":"The ratio parts should be added, not doubled or multiplied together. For 1:4, the total number of parts is $1 + 4 = 5$."}]},{"id":"c063607c-97ae-45e2-8ea9-e740999a13ea","cardType":"basic","points":1,"front":"An element has isotopes with masses 10 and 11 in a 1:4 ratio. What is its $A_r$?","back":"10.8","mcqOptions":[{"text":"10.8","correct":true,"explanation":"The weighted average is $\\frac{(10 \\times 1) + (11 \\times 4)}{1 + 4} = \\frac{54}{5} = 10.8$."},{"text":"10.2","correct":false,"explanation":"This gives too much weight to mass 10, reversing the ratio’s effect. Mass 11 occurs in four of the five parts, so the correct weighted average is 10.8."},{"text":"10.5","correct":false,"explanation":"This is the simple mean of 10 and 11 and assumes equal abundances. The 1:4 ratio is unequal, producing the weighted average 10.8."},{"text":"11.2","correct":false,"explanation":"This result is above the heaviest isotope mass, which cannot happen for a weighted average of 10 and 11. Correct weighting gives 10.8."}]},{"id":"fcafbb08-4ee1-44c4-8053-7e9d8566aff6","cardType":"basic","points":3,"front":"State the number of protons, neutrons, and electrons in ${}^{27}_{13}Al^{3+}$.","back":"

Protons: 13
Neutrons: 14
Electrons: 10

","mcqOptions":[{"text":"

Protons: 13
Neutrons: 14
Electrons: 10

","correct":true,"explanation":"The atomic number gives 13 protons, and $27 - 13 = 14$ neutrons. A $3+$ ion has lost three electrons, leaving $13 - 3 = 10$."},{"text":"

Protons: 13
Neutrons: 14
Electrons: 16

","correct":false,"explanation":"A $3+$ charge means three electrons have been lost, not gained. Aluminium therefore has 10 electrons, while its 13 protons and 14 neutrons remain unchanged."},{"text":"

Protons: 13
Neutrons: 27
Electrons: 10

","correct":false,"explanation":"The upper number is the nucleon number, equal to protons plus neutrons, not neutrons alone. Neutrons are $27 - 13 = 14$, and the ion has 10 electrons."},{"text":"

Protons: 10
Neutrons: 14
Electrons: 13

","correct":false,"explanation":"The $3+$ charge changes electrons, not protons. Aluminium’s atomic number fixes 13 protons, its neutrons are $27 - 13 = 14$, and losing three electrons leaves 10."}]}]}],"examCountdown":null,"heading":"Isotopes","title":"Isotopes Flashcards","topbar":{"backHref":"/igcse/chemistry/cie/flashcards"},"topicSidebar":"$L38"}]}],"topicId":"24439df0-f327-52b4-a100-8d698bcbc607","walled":"$L39"}],"$L3a","$L3b"]