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1

periodicity

the trends that occur as you move across the periodic table

2

1st ionization energy

the energy needed to remove 1 mol of electrons from 1 mol of gaseous atoms

3

ionisation energy trend

decreases down a group and increases across a period

4

explanation of ionization energy trend

//electrons down a group have more shells+a larger radius-> electron shielding and distance=less attraction to nucleus// across a period more protons and electrons but no new shells so greater effective nuclear charge

5

trend of electronegativity

increases across a period and up a group

6

explanation of electronegativty trend

positive effctive attraction from nucleus is grater

7

atomic radius trend

decreases along a period

8

reason for atomic radius trend

more protons in nucleus, greater effective nuclear charge so the outer electrons are more attracted to the nucleus

9

electrons shielding

repulsion between electron shells

10

group 2 trends

down the group: reactivity increases, ionization energy decreases,atomic radius increases,melting point decreases

11

why does melting point decrease down group 2

the ions get bigger so the electrons holding it all together are further from the positive nucleus so they hold it together with less force

12

why does ionization energy decrease down group 2

outer shell electrons are further from the nucleus and increased electron shielding so its easier to remove them

13

Mg (s) + H20(l) ->

Mg(OH)2 (aq) + H2 (g)

14

Mg (s) + H20(g) ->

MgO (s) + H2 (g)

15

group 7 trends

down the group: atomic radius increases, melting point increases, electronegativity decreases, reactivity decreases down the group, ionization energy decreases down the group

16

explanation of group 7 meting points

induced dipole dipole interactions hold them together as the atoms get bigger there are more electrons so the induced dipole interactions are more powerful

17

reactivity of halogens

decreases down the group as it gets harder for them to gain an electron

18

precipitation reaction

a reaction in which two ionic solutions are mixed to give an insoluble compound

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precipitate

insoluble salt

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cations

positive

21

anions

negative

22

chlorine ion test

white AgCl precipitate forms when mixed with AgNO3, dissolves in dilute NH3

23

bromide ion test

cream AgBr precipitate forms when mixed with AgNO3, dissolves in concentrated NH3

24

iodide ion test

yellow AgI precipitate forms when mixed with AgNO3 does not solved

25

disproportiation reactions

oxidation and reduction happen to the same species in the reaction

26

displacement reaction

reaction where a more reactive halogen takes the place of a less reactive one

27

halogens as oxidizing agents

halogens take an electron from other elements to complete their outer shell oxidizing them

28

melting point trend of period 2

increases consistently between the 1st three elements(because they are metals and the charge increases->more electrons in the cloud and decreasing radius), big jump to silicon (because its a giant covalent structure) low temps for the last 3 because they are simple covalent structures the noble gas has the lowest temp-> has an atomic tructure

29

test for NH4+

add sodium hydroxide NH4+ ions react with OH- ions to produce NH3 and H20 the ammonia gas will turn litmus paper blue

30

test for CO3 2-

CO3 2- reacts with H+ ions (acids) CO2 is formed - it will turn limewater cloudy