2023 DMMC杜克大学青少年数学大会报名正式开启！
始于2005年，国际名校广泛认可 全美Top10杜克大学支持举办 USMCA全美数学挑战联盟成员之一 杜克大学 青少年大会 DMMC报名后动 强调数学思维，激发兴趣探索 证明数学进阶能力 锻炼快速反应、灵活性及团队协作能力 ...
Edexcel A Level Chemistry:复习笔记1.5.3 Hydrogen Bonding
Hydrogen Bonding Interactions Examples of compounds that can form hydrogen bonds are: Alcohols (contains an O-H bond) Ammonia (contains an N-H bond) Amines (contains an N-H bond) Carboxylic ...
Edexcel A Level Chemistry:复习笔记1.5.2 Intermolecular Forces
Intermolecular Forces Intramolecular forces Intramolecular forces are forces within a molecule and are usually covalent bonds Covalent bonds are formed when the outer electrons of two atoms ...
Edexcel A Level Chemistry:复习笔记1.5.1 Electronegativity
Defining Electronegativity Electronegativity is the power of an atom to attract the pair of electrons in a covalent bond towards itself The electron distribution in a covalent bond between e...
Edexcel A Level Chemistry:复习笔记1.4.8 Shapes of Covalent Compounds
Electron Pair Repulsion & Shape The valence shell electron pair repulsion theory (VSEPR) predicts the shape and bond angles of molecules Electrons are negatively charged and will repel o...
Edexcel A Level Chemistry:复习笔记1.4.7 Bond Length & Bond Strength
Bond Length & Bond Strength Bond energy The bond energy is the energy required to break one mole of a particular covalent bond in the gaseous states Bond energy has units of kJ mol-1 &nb...
Edexcel A Level Chemistry:复习笔记1.4.6 Covalent Dot-and-Cross Diagrams
Covalent Dot-and-Cross Diagrams Covalent compounds The atoms in covalent compounds will share their outer valence electrons to achieve a noble gas configuration Dot-and-cross diagrams of cov...
Edexcel A Level Chemistry:复习笔记1.4.5 Covalent Bonding Overview
Covalent Bonding Covalent bonding occurs between two non-metals A covalent bond involves the electrostatic attraction between nuclei of two atoms and the bonding electrons of their outer she...
Edexcel A Level Chemistry:复习笔记1.4.4 Physical Properties of Ionic Compounds
Physical Properties of Ionic Compounds Most ionic, metallic and covalent solids are crystalline lattices The ions, atoms or molecules are arranged in a regular and repeating arrangement Gian...
