finishing touches - stuff to know that i didnt know
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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how does phosphorus exist
as P4 molecules
how does sulfur exist
as s8 molecules
the first 20 elements in the periodic table are catagorised according to bonding and structure. what are the elements catagorised into metallic?
• lithium • beryllium • sodium • magnesium • aluminium • potassium • calcium
the first 20 elements in the periodic table are categorised according to bonding and structure. which elements are categorised into covalent molecular?
• H2 • N2 • O2 • F2 • Cl2 • P4 • S8 • fullerenes eg C60
the first 20 elements in the periodic table are categorised according to bonding and structure. which elements are categorised into covalent network?
• Boron • Carbon - diamond, graphite • Silicon
the first 20 elements in the periodic table are categorised according to bonding and structure. whiche elements are categorised into monatomic?
noble gases
what are the steps to balancing a redox equation
• balance the main element • add water to balance oxygen atoms • add hydrogen ions to balance hydrogen atoms • add electrons to the same side as the hydrogen ions to balance the charge
what are strong reducing agents
carbon monoxide gas
what are strong oxidising agents
• hydrogen peroxide (H2O2) - dichromate (Cr2O7) and permangenate (MnO4) group ions -
what does the oxidation of edible oils result in
rancidity
what does distillation do
separates chemicals with different boiling points
what does chromatography do
separates chemicals due to difference in polarity or size
what are factors to control in chromatography
the temperature of the column because increasing the temperature would increase the kinetic energy of the particles and they would pass through the column more quickly. size because smaller molecules will pass through the column more quickly than larger molecules
describe how to prepare a burette for titration
• rinse with whatever solution is being used • fill buretted above the scale with the solution • remove filter funnel • open tap to drain some of the solution to ensure there are no air bubbles • reading should be taken from the bottom of the meniscus
what is the reduction reaction in benedicts solution
Cu2- + e- –> Cu+
what is the reduction reaction in tollens reagent
Ag+ + e- –> Ag2+
what is the reduction reaction in acidified dichromate
Cr207 2- + 14H+ + 6e- –> 2Cr3+ + 7H2O
what is the reduction reaction in acidified permangenate
MnO4- +8H+ +5e- → Mn2+ + 4H2O
why should one of the reactants always be in excess
to ensure that all of the limiting reactant is used up - for instance an ecess of sodium hydroxide allows to ensure that all chlorine is used up and prevents it from being released