module 3 Flashcards by ; ;

define the first ionisation energy

energy required to remove one electron from each atom in one mole of gaseous atoms of an element

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what electron will experience least nuclear attraction

highest energy level

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how does atomic radius affect the ionisation energy

F of attraction falls off sharply with increasing distance

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how does nuclear charge affect the ionisation energy

more protons in the nucleus, the greater the nuclear attraction of the outermost electron

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how does electron shielding affect the ionisation energy

inner-shell e- repel outer-shell e-(shielding effect) which reduces the nuclear attraction of the outer electrons

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how does an unpaired electron increase the ionisation energy

single electron pulled closer to the nucleus so the nuclear attraction increases so the ionisation energy increases

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what is the trend in ionisation energy across the period

increase

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what is the trend in ionisation energy for periods at the end of the table and periods at the start

sharp decrease

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what is the trend in ionisation energy down the group

decrease

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explain the trend in first IE down the group

atomic radius increases

shielding increases

outweighs the effect of the nuclear charge
so nuclear attraction decreases

so first IE decreases

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explain the trend in first IE across a period

nuclear charge increases

(similar shielding)

nuclear attraction increases

atomic radius decreases

first IE increases

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explain the lower IE of oxygen compared to nitrogen

outer electrons in same sub-shell

oxygen has a paired e- , the e- repel each other making it easier to remove

therefore, the IE of oxygen is less

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outline the properties of metals

strong metallic bonds

high electrical conductivity

high melting & boiling point

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what does the melting point of a metal depend upon

the strength of the metallic bonds

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do metals dissolve

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outline the melting&boiling points, the solubility and electrical conductivity of giant covalent structures

high melting & boiling points

insoluble

non-conductor of electricity (except graphene)

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describe the trend in melting point across period 2 and 3

increases from group 1-14

sharp decrease between 14-15

m.p. remains low from 15-18

define a reducing agent

something that reduces another species

group 2 elements + oxygen –>

metal oxide

group 2 elements + water –>

alkaline hydroxide + hydrogen gas

explain the increase in reactivity down group 2

nuclear attraction decreases

as a result of more atomic radius and more shielding

when the alkaline hydroxide produced becomes saturated, what happens

M2+ + 2OH- –> M(OH)2 (s)

precipitate forms

what is the use of calcium hydroxide

neutralises acidic soils

what are group 2 hydroxides and carbonates used for

digestion tablets

neutralises stomach acids

what happens when a solution of chlorine is added to an aqueous solution of bromide and iodide ions

chlorine is more reactive the halogen displaces the halide from solution changing the colour of the solution

what do chlorine, bromine and iodine make the solution in water

chlorine -- pale green bromine -- orange iodine -- brown

what do chlorine, bromine and iodine make the solution in cyclohexane

chlorine -- pale green bromine -- orange iodine -- violet

a solution of chlorine is added to a solution containing iodide ions what's the colour?

purple iodine is formed (chlorine displaces)

Cl2 + H2O -->

HClO + HCl

what causes the indicator paper to bleach after it turns red when added to a solution of water and chlorine

chloric(I) acid acts as a weak bleach

how does chlorine kill bacteria

chlorine and water form HClO and HCl bacteria are killed by the HClO and ClO-

Cl2 + 2NaOH -->

NaClO + NaCl + H2O

compare the reaction with water and chlorine, and chlorine and NaOH

ClO- formed at a larger concentration when chlorine reacts with NaOH

describe the test for a carbonate

add d. nitric acid bubble the gas produced through lime water (aqueous Ca(OH)2) lime water turns milky (calcium carbonate produced)

describe the test for sulfate

add barium ions to solution forming a ppt. Ba2+ + SO4 2- --> BaSO4

why is carbonate test performed first

neither sulfate nor halide ions produce bubbles with dilute acid

why is the sulfate test done after the carbonate test

BaCO3 is also white

why is the halide test performed last

Ag2CO3 and Ag2SO4 form ppt

when testing for a mixture of ions, how do you tweak each test

carbonate test continue adding d. nitric acid until the bubbling stops sulfate test add excess of Ba(NO3)2 halide test add AgNO3 before doing the test, then add NH3 to confirm which halide

describe the test for ammonium ions

add NaOH (ammonia gas produces) warm solution to release ammonia gas test with moist indicator paper