1- ATOMIC STRUCTURE AND PERIODIC TABLE Flashcards

Question

practical explain paper chromatography

Answer 1

separating different dyes in an ink 1) draw a line near the bottom of a sheet of filter paper(use pencil bc they are insoluble and wont dissolve in solvent) 2) add spot of ink to line and place sheet in a beaker of solvent e.g. water 3) solvent depends on what is being tested (some compounds dissolve well in water, others in ethanol) 4) make sure ink isnt touching solvent as you dont want it to dissolve 5) place lid on top of container to stop solvent from evaporating 6) solvent seeps up the paper, carries ink with it 7) each different dye in ink will move up paper at different rate so dyes will separate out, each dye will form a spot in a different place- 1 spot per dye in ink 8) if any of the dyes are insoluble in solvent theyll stay on baseline 9) when solvent has nearly reached top of paper =take paper out of beaker and leave it to dry end result is a pattern of spots called chromatogram

Answer 2

used if product is an insoluble solid that needs to be separated from a liquid reaction mixture can be used in purification as well e.g. solid impurities in the reaction mixture can be separated out using filtration

Answer 3

evaporation 1-pour solution into an evaporating dish 2-slowly heat solution, solvent will evaporate and solution will get more concentrated then crystals will start to form 3-keep heating the evaporating dish until all is left is dry crystals you can only use this method if the salt doesnt decompose when it is heated if it does decompose you need to use crystallisation

Answer 4

1- pour solution into evaporating dish and gently heat solution, some solvent will evaporate and solution will get more concentrated 2- once some of the solvent has evaporated or when you see crystals start to form (point of crystallisation) remove dish from heat and leave solution to cool 3- salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution 4- filter the crystals out of the solution and leave them in a warm place to dry (you could use a drying over or a desiccator)

Answer 5

1- pour solution into evaporating dish and gently heat solution, some solvent will evaporate and solution will get more concentrated 2- once some of the solvent has evaporated or when you see crystals start to form (point of crystallisation) remove dish from heat and leave solution to cool 3- salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution 4- filter the crystals out of the solution and leave them in a warm place to dry (you could use a drying over or a desiccator)

Answer 6

rock salt is simply a mixture of salt and sand(spread it on roads in winter) salt and sand are both compounds but salt dissolves in water and sand does not difference in physical properties helps separate them 1- grind mixture to make sure salt crystals are small so dissolves easily 2- put mixture in water & stir, salt will dissolve but sand wont 3- filter mixture, grains of sand wont fit through tiny holes in filter paper so they collect on the paper instead 4-salt passes through the filter paper as part of solution 5- evaporate water from salt so it forms dry crystals

Answer 7

its used for separating a liquid out from a solution 1-solution is heated, part of solution with lowest boiling point evaporates first vapour is then cooled, condenses and collected 2-rest of solution is left behind in the flask 3- you can use this to get pure water from seawater as water evaporates and is condensed and collected and you end up with salt in a flask

Answer 8

you can only use it to separate things with very different boiling points if the temperature goes higher than the boiling point of the substance with the higher boiling point, they will mix again if you have a mixture of liquids with similar boiling points you need to use fractional distillation

Answer 9

to separate a mixture of liquids 1- put mixture in a flask and stick a fractioning column on top then heat it 2- different liquids will all have different boiling points so they will evaporate at different temperatures 3- liquid with lowest boiling point evaporates first, when temperature on thermometer matches boiling point of liquid it will reach the top of the column 4-liquids with higher boiling points might also start to evaporate but column is cooler towards top so they will only get part of the way up before condensing and running back down to the flash 5- when first liquid has been collected, you raise temperature until next one reaches the top

Answer 10

solid spheres different spheres made of different elements

Answer 11

concluded from his experiments that atoms were not solid spheres his measurements of charge and mass showed that an atom must contain even smaller negatively charged particles- electrons new theory was plum pudding model= ball of positive charge with electrons stuck in it

Answer 12

alpha scattering experiment fired positively charged alpha particles at thin sheet of gold, =most particles went straight through gold sheet, some deflected more than expected, small number deflected backwards so plum pudding was not right this explained the nuclear model of the atom, there was instead a positively charged nucleus in the middle where most of the mass was concentrated, negative electrons surrounding the nucleus so most of atom was empty space when alpha particles came near concentrated positive charge of the nucleus, they were deflected if they were fired directly at the nucleus, they were deflected backwards otherwise they passed through empty space

Answer 13

suggested all the electrons were contained in shells the electrons orbit the nucleus in fixed shells and arent anywhere inbetween, each shell is a fixed distance from the nucleus his theory of atomic structure was supported by many experiments was supported by experiemnts and explained observations made by scientists

Answer 14

further experiments by rutherford and others showed that nucleus can be divided into smaller particles which each have same charge as a hydrogen nucleus = particles named protons

Answer 15

he carried out an experiment which provided evidence for neutral particles in the nucleus called neutrons discovey of neutrons resulted in model of the atom which is pretty close to the nuclear model

Answer 16

electrons always occupy shells (energy levels) lowest energy level is always filled first only 2 electrons on first shell 8 on 2nd and 3rd shell atoms are always trying to get a full shell e.g. noble gases = group 0 so in most atoms the outer shell is not full and this makes the atom want to react to fill it

Answer 17

arranged by atomic mass = physical and chemical properties = their relative atomic mass = the only thing they could measure was relative atomic mass so known elements arranged in order of atomic mass then periodic pattern was noticed in properties of elements early periodic table not complete, some elements placed in wrong group bc elements placed in order of relative atomic mass and not properties

Answer 18

left gaps and predicted new elements he took 50 known elements and arranged them in his table with gaps he put elements in order of atomic mass but did switch the order if the properties meant it should be changed eg with Te and I - iodine has smaller relative atomic mass but placed after terellium as it has similar properties to the elements in that group gaps left in table to make sure elements with similar properties stayed in same groups, gaps indicated existence of undiscovered elements , allowed mendeleev to predict what their properties might be when found they fitted the pattern,helped confirm his idea

Answer 19

he was correct not to place elements in a strict order of atomic mass but to also take in account their properties isotopes of the same element have different atomic masses but same chemical properties so occupy same position on periodic table

Answer 20

increasing atomic (proton) number so repeating patterns in the properties if elements properties arre said to occur periodically metals are found to the left non metals are found to the right

Answer 21

elements with similar properties form columns vertical columns are called groups group number tells you how many electrons are in outer shell (but for group 0 there are 2 electrons on outer shell) if you know properties of 1 element you can predict properties of other elements in group e.g. group 1 all metals and react in similar ways also shows trends in reactivity

Answer 22

elements react more vigourously as you go down the group

Answer 23

reactivity decreases as you go down the group

Answer 24

each new period represents another full shell of electrons

Answer 25

they can form positive ions when they react towards the bottom and left of the periodic table most elements in periodic table are metals non metals are at far right and top of periodic table they dont generally form positive ions when reacting

Answer 26

atoms generally react to form a full outer shell by losing/gaining/sharing electrons metals to left of periodic table dont have many electrons to remove and metals near bottom have outer electrons that are far away from the nucleus so theres a weaker attraction so not much energy is needed to remove electrons so its easier for elements to react to form positive ions to form a full outer shell

Answer 27

forming positive ions is much more difficult they have lots of electrons to remove to get a full outer shell or towards top where outer electrons are closer to nucleus to feel a stronger attraction it is easier for them to share or gain electrons to get a full outer shell

Answer 28

strong (hard to break) but can be bent or hammered into different shapes (malleable) great at conducting heat and electricity high boiling points and melting points

Answer 29

dont have metallic bonding dull looking more brittle arent always solids at room temperature dont generally conduct electricity often have low density

Answer 30

in the centre of the periodic table theyre typical metals, 'proper metals' good conductors of heat and electricity very dense, strong and shiny they can have more than one ion e.g. Cu can from Cu+ and Cu2+ Cobalt can form Co2+ and Co3+ transition metal ions are often coloured so compounds that contain them are colourful e.g. potassium chromate is yellow, potassium manganate is purple transition metal compounds make good catalysts e.g. nickel based catalyst is used in hydrogenation of alkenes & iron catalyst is used in Haber process to make ammonia

Answer 31

lithium sodium potassium rubidium caesium francium

Answer 32

they all have one electron in their outer shell which makes the very reactive and they are more ready to lose that electron to become a positive ion in order to gain a full outer shell this gives them similar properties alkali metals are all soft and have a low density

Answer 33

1- increasing reactivity= the outer electron is more easily lost as the attraction between the nucleus and electron decreases because the electron is further away from the nucleus the further down the group you go 2- lower melting and boiling points 3- higher relative atomic mass

Answer 34

1- increasing reactivity= the outer electron is more easily lost as the attraction between the nucleus and electron decreases because the electron is further away from the nucleus the further down the group you go 2- lower melting and boiling points 3- higher relative atomic mass

Answer 35

1- increasing reactivity= the outer electron is more easily lost as the attraction between the nucleus and electron decreases because the electron is further away from the nucleus the further down the group you go 2- lower melting and boiling points 3- higher relative atomic mass

Answer 36

group 1 metals dont need much energy to lose their 1 outer electron to form a full outer shell so they readily form 1+ ions so its easy for them to lose their outer electron that they only ever react to form ionic compounds these compounds are generally white solids that dissolve in water to form colour less solutions

Answer 37

-reacts vigorously to produce hydrogen gas and metal hydroxides: salts that dissolve in water to produce alkaline solutions - the more reactive(lower down the group) an alkali metal is the more violent the reaction is - the amount of energy given out by the reaction increases down the group: the reaction with potassium releases enough energy to ignite hydrogen e.g. 2Na + 2H2O => 2NaOH + H2 sodium + water => sodium hydroxide + hydrogen

Answer 38

they react vigorously when heated in chlorine gas to form white metal chloride salts as you go down the group,reactivity increases so the reaction with chlorine becomes more vigorous

Answer 39

they react with oxygen to form a metal oxide different types of oxides form depending on the group 1 metal =lithium reacts to form lithium oxide (Li2O) =sodium forms a mixture of sodium oxide(Na2O) and sodium peroxide (Na2O2) =potassium forms mixture of potassium peroxide (K2O2) and potassium superoxide (KO2)

Answer 40

group 1 metals are much more reactive thn transition metals they react more vigorously in water,oxygen or group 1 elements G1 is less dense,strong,hard than the transition metals and have much lower melting points (e.g. manganese melts at 2000 degrees celsius, sodium melts at 98 degrees celsius)

Answer 41

flourine chlorine bromine iodine astatine

Answer 42

flourine is a very reactive poisonous yellow gas chlorine is a fairly reactive poisonous dense green gas bromine is dense poisonous red/brown volatile liquid iodine is dark grey crystalline solid or purple vapour all exists as molecules (pairs of atoms)

Answer 43

as you go down the group it becomes less reactive(harder to gain extra electron because outer shell is further away from nucleus) - higher melting and boiling points -higher relative atmoic mass they all react in similar ways as they all have 7 electrons on their outer shell

Answer 44

halogen atoms share electrons via covalent bonding with other nonmetals to achieve full outer shell e.g. HCl, PCl5, HF, CCI4 contain covalent bonds the compounds that form when halogens react with non metals all have simple molecular structures

Answer 45

halogens form 1- ions called halides (F-, Cl-, Br-, I-) when they bond with metals e.g. Na+Cl-, Fe3+Br-3 the compounds that form ionic sturctures

Answer 46

halogens form 1- ions called halides (F-, Cl-, Br-, I-) when they bond with metals e.g. Na+Cl-, Fe3+Br-3 the compounds that form ionic sturctures

Answer 47

a displacement reaction occurs between a more reactive halogen and the salt of a less reactive one e.g. chlorine can displace bromine and iodine from an aqueous solution of its salt(bromide or iodide) bromine will also displace iodine because of the trend in reactivity Cl 2(g) + 2Kl(aq) => I2 (aq)+ 2KCl(aq) pale green brown Cl2(g)+ 2KBr (aq)=> Br2(aq) + 2KCl(aq) pale green orange

Answer 48

helium neon argon krypton xenon radon

Answer 49

they all have 8 electrons in their outer energy level apart from helium which has 2 giving them a full outer shell as their outer shell us energetically stable they dont need to give up or gain electrons to become more stable so they are more or less inert= dont react much# they exist as monatomic gases (single atoms not bonded to each other) all elements in group 0 are colourless gases at room temperature as noble gases are inert theyre non flammable: they wont set on fire

Answer 50

boiling points of noble gases increase as you move down the group along with increasing relative atomic mass increase in boiling point due to an increase in the number of electrons in each atom leading to greater intermolecular forces between them which need to be overcome

Answer 51

helium has a lower boiling point than neon so helium must be a gas at 25 degrees

Answer 52

xenon is inbetween both of these elements (-153)+(-62) =-215 -215 / 2 = -107.5 which is approxiamately -108 degrees celsius