Group 2: Trends Chemical trends All elements in Group 2 (also called?alkali earth metals)?have two electrons in their?outermost principal quantum shell All Group 2 metals can form?ionic?compounds?i...
The Periodic Table: Structure & Classification The?periodic table?is a list of all known elements arranged in order of?increasing atomic number,?from 1 to 118. In addition to this, the elements...
Oxidation & Reduction There are three definitions of?oxidation?and?reduction? used in different branches of chemistry Oxidation?and?reduction?can be used to describe any of the following proces...
Reversible Reactions & Dynamic Equilibrium Reversible reaction Some reactions go to completion where the reactants are used up to form the products and the reaction stops when all of the reacta...
Collision Theory Collision theory The?collision theory?states that for a chemical reaction to take place the particles need to?collide?with each other in the correct?orientation?and with enough?ene...
英國教育可以分兩個系統(tǒng)：公立教育和私立教育。這兩種教育主要區(qū)別在于， 公立教育系統(tǒng)里學校的財政開支和管理由中央政府或者當?shù)卣M行管控。大部分公立學校為走讀學校， 全英共有39所公立寄宿制學校， 但這些...
USACO 美國計算機奧林匹克學術活動 United States of America Computing Olympiad 簡稱USACO，USACO學術活動是美國最具認可度的計算機學術活動，用于選拔美國參加全球信息奧林匹克學術活動（IOI）的國家隊，學術...
Bond Energy During a reaction, enthalpy changes take place because bonds are being broken and formed Energy (in the form of heat) is needed to overcome attractive forces between atoms Bond breaking...
Electron Pairs The?valence shell electron pair repulsion theory?(VSEPR) predicts the shape and bond angles of molecules Electrons are?negatively charged?and will repel other electrons when close to...
State Changes Changes of state are?physical changes?that are reversible These changes do not change the chemical properties or chemical makeup of the substances involved Vaporization?includes?evapo...
Mole & Avogadro Constant The?Avogadro constant?(NA?or?L) is the number of particles equivalent to the relative?atomic?mass?or?molecular mass?of a substance The Avogadro constant applies to atom...
Relative Masses Atomic Mass Unit The mass of a single atom is so small that it is impossible to weigh it directly Atomic masses are therefore defined in terms of a?standard?atom which is called the...
