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Students in Grade 13 had the second-highest depression and anxiety scores, with examination-related issues being the most commonly cited problem. Of the 445 students assessed, 22.9% of Grade 12 students and 28.6% of Grade 13 students reportedly had severe depression , while 28.6% of Grade 12 students and 32.1% of Grade 13 students experienced ...
A past paper is an examination paper from a previous year or previous years, usually used either for exam practice or for tests such as University of Oxford, [1] [2] University of Cambridge [3] College Collections. Exam candidates find past papers valuable in test preparation.
The overall geometry is further refined by distinguishing between bonding and nonbonding electron pairs. The bonding electron pair shared in a sigma bond with an adjacent atom lies further from the central atom than a nonbonding (lone) pair of that atom, which is held close to its positively charged nucleus. VSEPR theory therefore views ...
The strong bonding of metals in liquid form demonstrates that the energy of a metallic bond is not highly dependent on the direction of the bond; this lack of bond directionality is a direct consequence of electron delocalization, and is best understood in contrast to the directional bonding of covalent bonds.
In coordination chemistry, a ligand [a] is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. [1]
Chelation (/ k iː ˈ l eɪ ʃ ən /) is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. [1] [2] These ligands are called chelants, chelators, chelating agents, or ...
AQA Education, [1] trading as AQA (formerly the Assessment and Qualifications Alliance), is an awarding body in England, Wales and Northern Ireland. It compiles specifications and holds examinations in various subjects at GCSE, AS and A Level and offers vocational qualifications. AQA is a registered charity and independent of the government.
In physics and chemistry, binding energy is the smallest amount of energy required to remove a particle from a system of particles or to disassemble a system of particles into individual parts. [1] In the former meaning the term is predominantly used in condensed matter physics , atomic physics , and chemistry, whereas in nuclear physics the ...