Edexcel IGCSE Maths复习笔记 1.10.1 Rounding & Estimation
Edexcel IGCSE Maths复习笔记 1.10.1 Rounding & Estimation Why use estimation? We estimate to find approximations for difficult sums Or to check our answers are about the right size (right order ...
Edexcel IGCSE Maths复习笔记 1.10.1 Rounding & Estimation Why use estimation? We estimate to find approximations for difficult sums Or to check our answers are about the right size (right order ...
又到一年毕业季。 对于留学生来说,回国的第一件事就是要将自己的海外学历进行认证,它不仅是找工作的必备材料,也是享受留学回国政策的一大凭证! 最近,教育部留学服务中心发布了最新的海外学历认证规范通知。...
UKChO 英国化学奥林匹克学术活动(UK Chemistry Olympiad)由英国皇家化学学会主办。英国皇家化学会是全球具有非凡影响力的化学学术组织之一,汇聚来自世界各地的化学科学家。英国化学奥林匹克学术活动中的试题会...
Reactivity of Halogenoalkanes The halogenoalkanes have different rates of substitution reactions Since substitution reactions involve breaking the carbon-halogen bond the bond energies can b...
Fractional Distillation Crude oil is currently the world's main source of organic chemicals As a mixture, it isn’t a very useful substance, but the different hydrocarbons that make up the mixture, ...
Organic Definitions & Terminology Organic chemistry is the chemistry of carbon compounds Carbon forms a vast number of compounds because it can form strong covalent bonds with itself This enabl...
Group 7: Physical Properties The group 7 elements are called halogens The halogens have uses in water purification and as bleaching agents (chlorine), as flame-retardants and fire extinguish...
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...
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