Chemistry Revision Questions PDF

**Chemistry revision questions** **Who was John dalton? Presented the first theory of atomism** **What was included in his version of the atom? A tiny round, hard sphere** **How did that shape modern day atomic discoveries? We now know that the atom has roughly circular shells** **What is atomic...

**Chemistry revision questions** **Who was John dalton? Presented the first theory of atomism** **What was included in his version of the atom? A tiny round, hard sphere** **How did that shape modern day atomic discoveries? We now know that the atom has roughly circular shells** **What is atomic mass? (mass number) the sum of protons and neutrons in the nucleus.** **What is an atomic number? The number of protons in the nucleus** **What do groups do? Columns- determine the number of electrons in the outer shell** **What do periods do? Rows- number of shells** **How to calculate a relative atomic mass? Sum of (total mass x abundance)/ total abundance** **What do cooling curves show? When changes of state occur in relation to temp and time** **What are all the changes of state? Sublimation, deposition, melting, freezing** **Differences between a physical and chemical change? Physical can be reversed** **What temperature is approx room temp? 25** **Volatile meaning? A liquid with weak intermolecular forces which changes state easily** **Viscous meaning? A thick sap like liquid** **What does a higher melting/ boiling point say about a particle's attractions? They are stronger** **How do impurities affect a cooling curve? There are no straight lines to show changes of state** **Why does the line stay flat during a change of state? Thermal energy becomes kinetic energy -change state.** **Explain how dissolving works? The solute is bombarded by the solvent -intermolecular forces break.** **What does RF stand for? Retention factor** **What is the equation to calculate RF? Distance traveled by spot/ " solvent (from the baseline)** **What are the samples called in chromatography? E numbers** **What two changes of state are required for simple distillation? Evaporation and condensation** **What does it rely on? Substances with different boiling points** **List the apparatus? Anti bumping granules, round bottomed flask, tripod and gauze, bunsen burner, heatproof mat, clamp stand, mixture (sample) condensing tube, beaker.** **Define potable water? Safe to drink** **Is fresh water or sea more common? Fresh** **Where can all types of water be stored? In a reservoir** **Where does groundwater come from? Natural/ man made aquifers** **What is the process of purifying sea water called? desalination** **What are the four key steps of water purification? Screening, sedimentation, filtration, sterilisation** **3 methods of sterilisation? UV exposure, bubbling chlorine gas, ozone exposure** **Why can tap water not be used in chemical analysis? Because it has small quantities of dissolved substances** **Define fractional distillation? Raw crude oil is separated into useful fractions (substances)** **What are the 6 fractions from lowest temp to highest? Petroleum gas, petrol, kerosene, diesel, industrial fuel, lubricating oil** **What are all fractions made of? Carbon polymers** **Does hotter = longer/shorter chains? longer** **What was Dalton\'s atomic structure called? Billiard ball** **4 things JD said about atoms? Tiny hard round spheres that make up everything. All atoms of an element are the same. Atoms cannot be created or destroyed.** **Word to describe noble gases being unreactive? inert** **Why are they unreactive? They have a full outer shell of electrons** **The more ---\-- The higher the reactivity? Shells** **Before Mendeleeve, how was the pt organised? Weight and reactivity** **Why did Mendeleeve not know about noble gasses? Elements were discovered based on reactions** **What is group one called? Alkali metals** **Group 2? Alkaline earth metals** **Group 7? Halogens** **Group 8/0? Noble gases** **In the middle? Transition metals** **Between metals and nonmetals? Metalloids.**