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Until 2014, the Standard Grade section of the site had 12 subjects: Biology, History, Chemistry, Computing Studies, Maths, English, Modern Studies (a course exclusive to Scotland), French, Physical Education, Geography, and Physics. [9] The site was updated in 2014 to replace the Standard Grade section with National 4 and National 5 sections.
In August 2018, Ofqual announced that it had intervened to adjust the GCSE Science grade boundaries for students who had taken the "higher tier" paper in its new double award science exams and performed poorly, due to an excessive number of students in danger of receiving a grade of "U" or "unclassified".
This target was reached nationally about 20 years later. David Blunkett went further and set schools the goal of 50% of 16-year-olds gaining 5 GCSEs or equivalent at grade C and above, although these grades were previously only obtained by the top 30%. This was achieved with the help of equivalent and largely vocational qualifications. [57]
The halogens (/ ˈ h æ l ə dʒ ə n, ˈ h eɪ-,-l oʊ-,-ˌ dʒ ɛ n / [1] [2] [3]) are a group in the periodic table consisting of six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors [4] would exclude tennessine as its chemistry is unknown and is theoretically expected to ...
The BBC Learning Zone (previously The Learning Zone) was an educational strand run by the BBC as an overnight service on BBC Two. It broadcast programming aimed at students in Primary, Secondary and Higher Education as well as to adult learners.
In organometallic chemistry, a coordinatively unsaturated complex has fewer than 18 valence electrons and thus is susceptible to oxidative addition or coordination of an additional ligand. Unsaturation is characteristic of many catalysts. The opposite of coordinatively unsaturated is coordinatively saturated.
A single-displacement reaction, also known as single replacement reaction or exchange reaction, is an archaic concept in chemistry. It describes the stoichiometry of some chemical reactions in which one element or ligand is replaced by atom or group. [1] [2] [3] It can be represented generically as:
Of the 94 natural elements, eighty have a stable isotope and one more has an almost-stable isotope (with a half-life of 2.01×10 19 years, over a billion times the age of the universe). [ 15 ] [ b ] Two more, thorium and uranium , have isotopes undergoing radioactive decay with a half-life comparable to the age of the Earth .