c number $Z$ in a neutral atom?","back":"They are equal.","points":1,"mcqOptions":[{"text":"They are equal.","correct":true,"explanation":"In a neutral atom, the negative charge from electrons exactly balances the positive charge from protons. Since $Z$ is the proton number, the electron number equals $Z$."},{"text":"There is one fewer electron.","correct":false,"explanation":"Having one fewer electron than protons describes a singly charged positive ion, not a neutral atom. A neutral atom has $Z$ electrons because $Z$ equals its proton number."},{"text":"There is one more electron.","correct":false,"explanation":"Having one more electron than protons describes a singly charged negative ion. In a neutral atom, electron and proton numbers are equal, so there are exactly $Z$ electrons."},{"text":"There are twice as many electrons.","correct":false,"explanation":"This incorrectly treats $Z$ as only half the particle count. Atomic number $Z$ directly gives the number of protons and, for a neutral atom, the number of electrons."}]},{"id":"c201c53d-cba9-43a6-9de0-1c5e2b7d2e4b","cardType":"basic","front":"Define an orbital.","back":"A region of space that can hold up to two electrons.","points":1,"mcqOptions":[{"text":"A region of space that can hold up to two electrons.","correct":true,"explanation":"An orbital is a region around the nucleus with a high probability of finding electrons. The Pauli exclusion principle limits each orbital to two electrons with opposite spins."},{"text":"A region of space that can hold up to six electrons.","correct":false,"explanation":"Six is the capacity of an entire p sub-shell containing three orbitals, not one orbital. Every individual orbital can hold no more than two electrons."},{"text":"A fixed path around the nucleus that holds two electrons.","correct":false,"explanation":"Electrons do not travel in fixed circular paths, as suggested by the simplified Bohr model. An orbital is a probability region that can contain up to two electrons."},{"text":"A region inside the nucleus that can hold two electrons.","correct":false,"explanation":"Orbitals describe regions around the nucleus, while the nucleus contains protons and neutrons. Each orbital outside the nucleus can accommodate up to two electrons."}]},{"id":"88706c5a-2740-4a34-bdf4-7677b8f52958","cardType":"basic","front":"State the maximum electron capacity for s, p, and d sub-shells.","back":"

s: 2
p: 6
d: 10

","points":1,"mcqOptions":[{"text":"

s: 2
p: 6
d: 10

","correct":true,"explanation":"The s, p, and d sub-shells contain one, three, and five orbitals respectively. Since each orbital holds two electrons, their maximum capacities are 2, 6, and 10."},{"text":"

s: 1
p: 3
d: 5

","correct":false,"explanation":"These values count the orbitals in each sub-shell rather than their electron capacities. Multiplying one, three, and five orbitals by two gives capacities of 2, 6, and 10."},{"text":"

s: 2
p: 8
d: 18

","correct":false,"explanation":"The values 2, 8, and 18 are maximum capacities of principal shells, not s, p, and d sub-shells. Their correct capacities are 2, 6, and 10."},{"text":"

s: 2
p: 4
d: 6

","correct":false,"explanation":"This pattern incorrectly increases capacity by only two for each successive sub-shell. Orbital counts rise from one to three to five, giving capacities of 2, 6, and 10."}]}]}],"examCountdown":{"examDate":"2027-05-28","paperLabel":"Paper 1"},"heading":"Electron configuration","title":"Electron configuration Flashcards