inorganic chemistry Flashcards

Question

what is the general trend for ionisation energies across a period

Answer 1

the ionisation energy increases going down any period this is because the number of protons increases but the shielding and the number of shells stays the same this increased nuclear charge means that it gets increasingly difficult to remove an electron

Answer 2

the number of oof filled inner levels increases down the group This results in an increase in shielding Also, the electron to be removed is at an increasing distance from the nucleus and is therefore held less strongly Thus the outer electrons get easier to remove going down a group because they are further away from the nucleus

Answer 3

moving from neon in Period 0 with electron arrangement 2,8 to sodium, 2,8,1 there is a sharp drop in the first ionisation energy This is because at sodium a new main level starts and so there is an increase in atomic radius, the outer electron is further from the nucleus, less strongly attracted and easier to remove

Answer 4

the first ionisation energy drops between GROUP 2 and GROUP 3 so that aluminium has lower ionisation energy than magnesium the ionisation energy drops again slightly between GROUP 5 ( phosphorus) and GROUP 6 (sulfur) similar patterns occur in other periods

Answer 5

magnesium loses an electron in 3s while magnesium loses an electron in 3p which is a higher energy level than magnesium so the electron can be lost easier

Answer 6

an electron in a pair will be easier to remove than one in an orbital on its own orbital because to os being repelled by the other electron phosphorus has no paired electrons in a p -orbital because each p -electron s in its own orbital sulfur has two of its p -- electrons paired in a p - orbital so one of these will be easier to remove than an unpaired one due to the repulsion of the other electron in the same orbital

Answer 7

elements in group 2 are called the alkaline earth metals this is because their oxides and hydroxides are alkaline

Answer 8

like group, they are s- block elements they are similar to group 1 but are less reactive

Answer 9

electron arrangement 2 electrons in outer s- orbital This s- orbital becomes further from the nucleus going down the group the sizes of the atoms the atoms get bigger going down the group. The atomic (metallic) radii increases because each element has an extra filled main level of electrons compared with the one above

Answer 10

group 2 elements are metals with high melting points typical of a giant metallic structure this is because going fon the group, the electrons in the "sea" of delocalised electrons are further away from the positive nuclei As a result, the strength of the metallic bonds decreases going down the group For this reason, the melting points of group 2 elements decrease slightly going down the group staring with calcium

Answer 11

in all their reactions, atoms in Group 2 lose their two outer electrons to form ions with two positive charges SO, an amount of energy equal to the sum of the first and second ionisation energies is needed for complete ionisation Both the first ionisation energy and the second ionisation decreases going down the group - it takes less energy to remove the electrons as they become further away from the positive nucleus The nucleus is more effectively shielded by more inner shells of electrons

Answer 12

oxidation is the loss of electrons so in all reactions the group 2 metals are oxidised

Answer 13

with water you see a trend in reactivity: - metals you get more reactive going down: These are also redox reactions The basic reaction (where M is any metal in Group 2\_) M(s) +2H2O - M(OH2)aq +H2

Answer 14

magnesium hydroxide is a milk of magnesia and is used in indigestion remedies to neutralise excess stomach acid

Answer 15

magnesium reacts very slowly with cold water but rapidly with steam to form an alkaline oxide and hydrogen Mg(s) + H2O - MgO(s) + H2

Answer 16

calcium react in the same way but more vigorous, even with cold water

Answer 17

strontium and barium reacts more vigorous

Answer 18

calcium hydroxide is sometimes slaked lime and is used to treat acidic soil Most plants have an optimum level of acidity or alkalinity in which they thrive e.g. grass grows best at a pH of 6

Answer 19

the hydroxides are all white solids

Answer 20

because it is in group 2 and needs 2 hydroxides

Answer 21

Mg(OH)2 (magnesium hydroxide) (milk of magnesia) is almost insoluble Ca(OH)2 calcium hydroxide, is sparingly soluble and a solution is used as lime water (slightly soluble) Strontium hydroxide Sr(OH)2 is more soluble Barium hydroxide Ba(OH)2 dissolves to produce alkaline solution: Ba(OH)2(s) + aq - Ba2+(aq) + 2OH-(aq) (soluble)

Answer 22

due to the trend in solubility in sulfates, barium sulfatesis virtually insoluble This means that it can be taken by mouth as a barium meal to outline the gut in medical x - rays ( the heavy barium atom is very good at absorbing x - rays) the test is safe, despite the fact that is barium compounds are highly toxic, because barium sulfate is so insoluble

Answer 23

the insolubility of barium sulfate is used in a simple test for sulfate ions in solution The solution is first acidified with nitric or hydrochloric acid The barium chloride solution is added to the solution under test and if sulfate is present a white precipitate of barium sulfate is formed

Answer 24

MgSO4 - soluble CaSO4 - slightly soluble SrSO4 - insoluble BaSO4 - insoluble

Answer 25

group 7 on the right - hand side of the Periodic Table - it is made up of non -metals - as elements they exist as diatomic molecules F2, Cl2, Br2 and I2 called the halogens

Answer 26

gaseous halogens vary in appearance e.g. Fluorine appears clear/ pale yellow gas Chlorine - a greenish gas Bromine - a red-brown liquid iodine - a black solid they get darker and denser going down the group they all have a characteristic "swimming - bath" smell

Answer 27

- many of these untypical properties stem from the fact that the F - F bond is unexpectedly weak, compared with the trend fo the rest of the halogen this is because the small size of the fluorine atom leads to repulsion between non - bonding electrons because they are so close

Answer 28

F - very reactive, toxic Cl - very reactive, toxic Br - very reactive, toxic I grey crystals, reactive, toxic

Answer 29

the size of the atom increases as it goes down the electronegativity of an atom decreases as it goes down the melting points increases as it goes down the boiling points increases as it goes down

Answer 30

atoms get bigger going down the group because each element has one extra filled main level of electrons compared with one above it

Answer 31

electronegativity is a measure of the ability of an atom to attract electrons, or electron density, towards itself within a covalent bond

Answer 32

electronengativity depends on the attraction between the nucleus and bonding electrons in the outer shell This in turn, depends on a balance between the number of protons in the nucleus (nuclear charge) and the distance between the nucleus and the bonding electrons plus the shielding effect of inner shells off electrons

Answer 33

the shared electrons in the H-X bond get further away from the nucleus as the atoms get larger going down the group This makes the shared electrons further from the halogens nucleus and increases the shielding by more inner shells of electrons

Answer 34

increases as you go down the group This is because larger atoms have more electrons and this makes the van der Waals forces between the molecules stronger

Answer 35

the lower the boiling point, the more volatile the element So chlorine which is a gas at room temperature is more volatile than iodine which is a solid

Answer 36

usually react by gaining electrons to become negative ions with a charge of -1 reactions are redox reactions - halogens are oxidising agents known

Answer 37

halogens will react with metal halides in solution in such away that the halide in the compound will be displaced by a more reactive halogen but not by a less reactive this is called a displacement reaction

Answer 38

e.g. chlorine will displace bromide ions, but iodine will not in this redox reaction the chlorine is acting as an oxidising agent, by removing electrons from Br- and oxidising 2Br- to Br2 (the oxidation number of the bromine increases from -1 to 0)

Answer 39

because it reacts with water

Answer 40

the oxidation of a halide by a halogen is the basis of a method for extracting bromine from seawater seawater contains small amounts of bromide ions which can be oxidised by chlorine to produce bromine: Cl2(aq) + 2Br-(aq) - Br2(aq) +2Cl-

Answer 41

iodine was discovered in 1811 It was extracted from kelp, which is obtained by burning seaweed Some iodine is still produced in this way Salts such as sodium chloride, potassium chloride, and potassium chloride and potassium sulfate are removed from the kelp by washing wit water The residue is then heated with manganese dioxide and concentrated sulfuric and iodine is liberated 2I- +MnO2 +4H+ - Mn2+ +2H2O +I2

Answer 42

halide ions can act as reducing agents these reactions the halide ions (give away) electrons and become halogens molecules

Answer 43

it is linked to the size of the ions the bigger the ion, the more easily it loses an electron This is because the electron is lost from the outer shell which is further from the nucleus as the ion gest larger so the attraction to the outer electron is less This trend can be seen in the reactions of solid Sodium halides with concentrated sulfuric acid

Answer 44

the products are all different and reflect the reducing powers of the halides ions shown above

Answer 45

in this reaction, drops of concentrated sulfuric acid are added to solid sodium chloride steamy fumes of hydrogen chloride are seen the solid product is sodium hydrogensulfate the reaction is: NaCl(s) + H2SO4 - NaHSO4(s) + HCl(g) This is not a redox reaction because no oxidation state has changed The chloride ion is too weak a reducing agent to reduce the sulfur (oxidation state = +6) in the sulfuric acid this reaction can be used to prepare hydrogen chloride gas which, because of this reaction was once called a salt gas similar reaction with sodium fluoride - the fluoride ion is an even weaker reducing agent than the chloride ion

Answer 46

you will see steamy fumes of hydrogen bromide and brown fumes of bromine - colourless sulfur dioxide is also formed Two reactions occur first sodium hydrogen sulfate and hydrogen bromide are produced (in a similar acid- base reaction to sodium chloride) NaBr(s) +H2SO4(l) - NaHSO4(s) +HBr(g) However, bromide ions are strong enough reducig agents to reduce the sulfur acid to sulfur dioxide The oxidation sate of the sulfur is reduced from +6 to +4 and that of bromine increases from - 1 to 0 This is a REDOX reaction the reactions are exothermic and some of the bromine vaporiese

Answer 47

you see steamy fumes of hydrogen iodine, the black solid of iodine, and the bad egg smell of hydrogen sulfide Yellow solid sulfur may also be seen colourless sulfur dioxide is also evolved SEVERAL REACTIONS OCCUR: - hydrogen iodine is produced in an acid - base reaction as before - iodine ions are better reducing agents than bromide ions so they reduce the sulfur in sulfuric acid even further (from +6 to 0 and -2) so that sulfur dioxide, sulfur and hydrogen sulfide gas are produced during the reduction from +6 to -2, the sulfur passes through oxidation state 0 and some yellow, solid sulfur may be seen

Answer 48

all metal halides (except fluorides) react with silver ions in an aqueous solution e.g. in silver nitrate to form a precipitate of the insoluble silver halide - silver fluoride does not form a precipitate because it is soluble in water 1. Dilute nitric acid HNO3 or (H+ aq) + NO-3(aq) is first added to the halide solution to get rid of any soluble carbonate CO2-(aq) or hydroxide OH- impurities - these would interfere with the test by forming insoluble silver carbonate 2. then add a few drops of silver nitrate solution and the halide precipitate forms

Answer 49

the reaction can be used as a test for halides because you can tell from the colour of the precipitate which halide has formed The colours of silver bromide and silver iodide are similar but if you add a few drops of concentrated ammonia solution, silver bromide dissolves but silver iodide does not

Answer 50

silver fluoride - no precipitate SILVER CHLORIDE - white precipitate dissolves in dilute ammonia SILVER BROMIDE - cream ppt dissolves in concentrated ammonia SILVER IODIDE - pale yellow ppt insoluble i concentrated ammonia

Answer 51

titanium is a very useful metal because it is: - abundant - has a low density - is corrosion resistant It is useful for making strong, light alloys for use in aircraft for example

Answer 52

titanium is extracted by reaction with a more reactive metal (e.g. Mg) steps in extracting titanium: 1. TiO2 (Solid) is converted to TiCl4 (liquid) at 900C 2. The TiCl4 is purified by fractional distillation in an argon atmosphere 3. The Ti is extracted by Mg in an argon atmosphere at 500C

Answer 53

the expensive cost of the Mg This is a batch process which makes it expensive because the process is slower (having to fill up and empty reactors take time) and requires more labour and the energy is lost when the reactor is cooled down after stopping 3. the process is also expensive due to the argon, and the need to remove moisture (because TiCl4 is susceptible to hydrolysis) 4. high temperature required in both steps

Answer 54

potassium chloride & chloride - very pale green solution, no reaction potassium bromide & chlorine - yellow solution, Cl has displaced Br potassium iodide &chlorie - brown solution CL has displaced I

Answer 55

the colour of the solution in the test tube shows which free halogen is presented in solution Chlorine - very pale green solution (often colourless) Bromine = yellow solution Iodine = brown solution (sometimes a black solid is present)

Answer 56

if you mix bleach with cold, dilute sodium hydroxide solution at room temperature, you get sodium chlorate(I) solution (NaClO) this is a common household bleach that kills bacteria

Answer 57

it is called disproportionation this is because in the reaction chlorine is both oxidised and reduced

Answer 58

2NaOH + Cl₂ → NaClO + NaCl + H₂O ClO^{- is the chlorate (I) ion} ^{Chlorine's oxidation state is +1 in this ion} ^{In NaCl the chlorine oxidation state is -1}

Answer 59

when you mix chlorine with water, it undergoes disproportionation You end up with a mixture of chloride ions and chlorate (I) ions

Answer 60

Cl₂+ H₂O ⇔ 2H⁺ + Cl^-+ ClO^-

Answer 61

Cl2 + H2O ⇔ 2H+ + Cl- + ½O₂

Answer 62

chlorate ions kill bacteria so adding chlorine or a compound that contains chlorate ions to water can make it safe to drink or swim in it it kills disease-causing microorganisms it prevents the growth of algae, eliminating bad tastes and smells, and removes discolouration caused by organic compounds however there are risks to using chlorine to treat water - chlorine gas is very harmful when breathed in - it irritates the respiratory system

Answer 63

the benefits outweigh the negatives/ the risks

inorganic chemistry Flashcards

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