INORGANIC - MOCKS Flashcards
what is periodicity?
regularly repeating pattern of atomic, physical and chemical properties with increasing atomic number
four blocks on the periodic table?
S = gp 1 + 2
d = transition
p = rhs
f = bottom
why does the first ionisation energy generally decrease down a group?
more shells
more shielding
easier to lose outer electron
why does Si have such a high melting/boiling point?
giant covalent structure
all silicon atoms held together with strong covalent bonds
require lots of energy to overcome
definition of first ionisation energy
energy required to remove one outer electron from one mole of gaseous atoms to produce one mole of gaseous ions with a 1+ charge
why does the first ionisation energy generally increase across period 3?
increasing nuclear charge
same shielding
stronger electrostatic attraction between outer electrons and nucleus so harder to remove the outer electron
why does the 1st ionisation energy in period 3 fall at ALUMINIUM?
aluminium outer electron = in 3p rather than 3s
higher energy level
slightly more distant from nucleus
partially screened by 3s electrons too
why does the first ionisation energy in period 3 fall at SULFUR?
in sulfur the electron is being removed from a PAIR
repulsion between two electrons in same orbital
why does melting point generally decrease down group 2?
more shielding
electrons in sea of delocalised electrons further from nucleus
metallic bond strength decreases
(Mg = lowest but no simple explanation)
how does the reaction with water change down the group?
gets more vigorous down the group
eg - M(s) + 2H2O(l) —- M(OH)2(aq) + H2(g)
reaction of magnesium with cold water + with steam
Mg and cold water —- very slow reaction
Mg and steam —- very rapid reaction - forms magnesium OXIDE
and hydrogen
trend in solubility of group 2 hydroxides down the group?
down group = more soluble
use of Mg(OH)2 (almost insoluble)
indigestion tablets
trend in solubility of group 2 sulfates down group 2?
become LESS soluble down the group
how can barium sulfate be used in medicine?
barium meal to outline the gut in medical x-rays
barium = highly toxic but BaSO4 is v insoluble so is safe
using barium sulfate to test for sulfate ions in solution?
- solution first acidified with nitric / hydrochloric acid
- barium chloride solution added
- if a sulfate is present a white precipitate of BaSO4 will form
trend in oxidising ability up the halogens?
oxidising ability of halogens INCREASES UP THE GROUP
reaction between chlorine and bromide ions
Cl2 + 2KBr —— Br2 + 2KCl
- bromine is formed so red-brown solution
- chlorine = oxidising agent
equation for formation of bleach - NaClO
2NaOH + Cl2 —— NaClO + NaCl + H2O
what type of reaction is the formation of bleach?
disproportionation
the OS of Cl increases and decreases as it is both oxidised and reduced
trend in halides as reducing agents?
reducing ability increases down the group
reaction of chloride ions with SULFURIC ACID?
add halide as a salt
NaCl + H2SO4 ——- NaHSO4 + HCl
HCl = misty white fumes
NaHSO4 = sodium hydrogen sulfate + made in all these reactions
reaction of fluoride ions with sulphuric acid?
NaF + H2SO4 —- NaHSO4 + HF
HF = misty white fumes
reaction of bromide ions with sulfuric acid
two reactions
NaBR + H2SO4 —– NaHSO4 + HBr (misty white fumes)
HBr = better reducing agent so reacts again with H2SO4
2HBr + H2SO4 —— Br2 + SO2 + 2H2O
reaction between iodide ions and sulfuric acid
NaI + H2SO4 —– NaHSO4 + HI
2HI + H2SO4 —- I2 + SO2 + 2H2O
6HI + SO2 —– H2S + 3I2 + 2H2O
describe the test for halides
+ nitric acid - HNO3 (to remove unwanted carbonate ions)
+ silver nitrate - AgNO3
results when testing for halide ions with
nitric acid + silver nitrate?
Cl- white ppt
Br- cream ppt
I- yellow ppt
testing further for halide ions after adding HNO3 and AgNO3?
add ammonia NH3
AgCl will dissolve in DILUTE NH3
AGBr will dissolve in CONCENTRATED NH3
AgI won’t dissolve in NH3
basic trend in oxidising in gp 7
a halogen will displace a halide from a solution if it is below it in the periodic table
what is meant by the thermal stability of the halides?
how easily a hydrogen halide is broken up into its constituent elements when heated
why does the thermal stability of the halides decrease down the group?
down group, covalent bonds are weaker and can be broken more easily upon heating
