PERIODICITY/ GROUP 2 METALS Flashcards
How are elements arranged in their periodic table?
elements are arranged according to their proton number
What does the group number indicate on the periodic table?
number of outer e- of an element
what are the 4 block of the periodic table
s
p
d
f
What is periodicity?
trends within periodic table
why does the radius decrease along period 3?
increase in charge
same number of shells so same shielding
outer e- attracted more strongly
state the general trend in the 1st ionisation energies of the period 3 elements sodium to Cl
increases
identify the element in P2 that has the highest 1st ionisation energy
Neon
Trend in atomic radius down a group?
atomic radius increases
why does atomic radius increases down a group?
more shells so increase shielding
greater distance between outer e- and nucleus so less attraction between nucleus and outer e-
atomic radius increases
trend in ionisation energy along a period?
ionisation energy increases
why does ionisation energy increases along a period?
atomic radius decreases
increases in charge
outer e- is strongly attracted to nucleus so requires so more energy required to remove outer e-
trend in ionisation energy down a period?
ionisation energy decreases
why does ionisation energy increases down a period?
attraction between nucleus and outer e- decreases
more shielding
less energy required to remove outer e-
what happens to melting point across P3? (6- marker)
STAGE 1
1.Na , Mg , Al have metallic bonding
2.higher density charge along Na=+1 , Mg=2+ , Al= 3+
increase in electrostatic forces of attraction from Na to Al so more energy needed to break them
STAGE 2
1.silicon has the highest melting point
2. Macromolecular structure , very similar to diamond held together by strong covalent bonds between atoms
3. requires a lot of energy to break
STAGE 3
1- P, S and Cl exsist as simple molecular.
2. P–> P4 S–> S8 Cl–> Cl2
3. S8 rings are the biggest of the 3 molecules so have the strongest induced dipole dipole
4. Cl2 atomic molecule are the smallest as weakest iduced dipole
5. Ar exsist as single atoms it has the weakest induced dipole dipole forces of all non-metal so lowest meting point
Trend in ionisation energy across P2? (6 marker)
STAGE 1
General increase in IE
same shielding as same number of shells
greater attraction between nucleus and outer e-
STAGE 2
B lower than Be
outer e- in 2P
higher in energy than 2S
STAGE 3
O lower than N
2 e- in 2P needed to be pair
e- pair repulsion
Write equation for the 1st ionisation energy of Mg
Mg(g) —> Mg+(g) + e-
How does reactivity with water change down group 2
Increases (Mg least—> Ba most)
As outer e- further from nucleus
more shielding
Write an equation for the reaction of Ba and water
Ba(s) + 2H20(I) –> Ba(OH)2(Aq) + H2
Write an equation for reaction of Mg and steam
Mg(s) + H2O(g) —> MgO(s) +H2(g)
What is the trend in hydroxide solubility down G2?
Increases down the group
Mg(OH)2 is almost insoluble
Ba(OH)2 creates a strong alkaline solution
What is the trend in sulphate solubility down G2?
Decreases down group
MgSO4 is soluble
BaSO4 is insoluble
Write the equations for the extraction of Titanium using Mg
TiO2 +2Cl2 +C —> TiCL4 + CO2
TiCl4(l) + 2Mg(s)—–> 2MgCl2 + Ti
What are flue gases?
gases produced by power stations which are harmful to the environment
How can CaO or CaCO3 be used to remove flue gases? (equation)
CaCO3(s) + SO2(g) —> CaSO3 (s) + CO2(g)
CaO(s) + SO2(g) —> CaSO3(s)
What is Ca(OH)2 used for?
write equations related to one of its uses
neutralise soil
Ca(OH)2(aq) + 2HCl(aq)—-> 2H2O(I) + CaCl2 (aq)
What is Mg(OH)2 used for?
Antacid to traet digestion
heartburn
What is a use of BaSO4? Why is this safe?
In barium metals to outline gut in X-rays
Ba2+ is toxic but is fine as barium sulphate is insoluble
How can BaCl2 be used to test for sulphate ions?
Add HCl , white ppt form =+ve
Ba”+ + SO4 2- —–> BaSO4
What happens to the 1st ionisation energy as you go down group 2? why?
increases down the group
increases shielding
increases atomic radius
weaker force between outer e- and nucleus
less energy needed to remove e-
Test for SO4 2- IONS
BaCl2
White ppt formed
Ba2+(aq) + SAO4 2-(aq) ————> BaSO4 (s)
Use of Mg(OH)2
Neutralize stomach acid
