s block

Question 1

What are the 2 ways to produce hydrogen and what are the equations involved?

Answer 1

1. Steam reforming
   CH4 + H2O (with 800 degrees and ni oxide) -> CO + 3H2

CO + H2O (200-450 degrees) Fe catalysts -> CO2 + H2

2. Electrolysis of water
   2H2O + 2H2 + O2

Question 2

What are 3 uses of hydrogen?

Answer 2

1. Production of ammonia
2. Production of methanol and organic compounds
3. Hydrogenation of unsaturated compounds

Question 3

What are the 3 types of binary hydrogen compounds?

Answer 3

Covalent hydrides: H + p block elements
Saline hydrides: H + s block/electropositive elements
Metallic hydrides: H + d/f block elements

Question 4

What are the 3 types of hydrogen atoms?

Answer 4

Protic hydrogen (H+)
Hydridic hydrogen (H-)
Radical hydrogen (H.)

Question 5

what are the 2 things that relate to the strength of a bond?

Answer 5

1. Orbital overlap
2. Ionic contribution to the bond

Question 6

what is a major factor to determine the strength of single and multiple bonds

Answer 6

single bonds: electronegativity
multiple bonds: orbital overlap

Question 7

what are the different types of ores?

Answer 7

oxides, sulfides, carbonates, native, noble, silicates

Question 8

what is the ionization energy equation?

Answer 8

IE = -Eorb x (Zeff/n)^2

Question 9

what is the equation to find the %of ionic bonding?

Answer 9

% = (Q / charge of an electrons) x 100

Question 10

what is the trend between orbital size and strength of bond?

Answer 10

larger orbital size -> more diffuse -> poorer overlap -> weaker bond -> more reactive

Question 11

when is the oxidation state of an element 0?

Answer 11

single atom, lattice, or moleculear form (eg. O2)

Question 12

what determines the charge on hydrogen?

Answer 12

the electronegativity of the element compared to hydrogen

Question 13

what is currently a developing use of hydrides?

Answer 13

storage for hydrogen (NaBH4 with water to form hydrogen gas) to be used in fuel cells

Question 14

what is the packing for all G1 metals?

Answer 14

BCC

Question 15

how is each G1 element produced?

Answer 15

Li and Na through electrolysis of molten chlorides (down cells)

K, Rb, Cs through reduction of its chloride with Na

Question 16

what are some uses of G1 elements?

Answer 16

Li -> solid state batteries (small = greater mobility)

Na: NaOH (industrial chemical) + NaCl (table salt and road clearing)

Question 17

what compounds do G1 elements form and what are their equations?

Answer 17

hydrides, hydroxides, oxides, carbonates and halides

Question 18

what are the 3 types of oxide ions?

Answer 18

oxide (O2-)
peroxide (O2 2-)
superoxide (O2 -)

Question 19

which oxide can be reacted with carbon dioxide to produce oxygen for breathing apparatus?

Answer 19

KO2

Question 20

what is the solubility of G1 salts dependent on?

Answer 20

large anion: solubility decreases down the group as larger ion means lower nuclear charge thus lower attraction to the solvent/water molecules

small anion: solubility increases down the group as the cation can be easily solvated and the bond between the cation and anion is weaker down the group due to poor orbital overlap thus more likely to be separated (soluble)

Question 21

how can the solubility of G1 elements be improved?

Answer 21

wrapping up the metal ions in macrocyclic crown ether ligands

Question 22

what are the irregularities of melting points in G2 elements?

Answer 22

caused by different packing structures (CCP is closer together than HCP thus sudden higher melting point of calcium)

Question 23

how are G2 elements produced?

Answer 23

Mg is the only element in G2 that is massed produced and it is done through the thermal decomposition of metal carbonates

Eg. from dolomite (MgCO3 . CaCO3)
-> lose CO2 first then react with Si to form Mg on its own

Question 24

what are some uses of G2 elements?

Answer 24

Be (high thermal conductivity, not magnetic): aerospace and alloying

Mg: aluminium alloys (increase resistance to corrosion and greater mechanical strength)

Question 25

what compounds do G2 elements form?
which elements do not form oxides and hydroxides and why?

Answer 25

oxides, halides, sulfides, nitrides and hydroxides

Be and Mg do not form hydroxides and oxides because they have a protective oxide layer that makes the metal kinetically inert

Question 26

why is Be different from the other elements in its group?

Answer 26

due to its high polarising power it can withstand the power of anions thus results in polar covalent compounds rather than ionic compounds

Question 27

what is the unique property of BeCl2?

Answer 27

in gas Be is linear

in solid state it forms chains due to donation of electron density from chlorine into electron deficient Be (not possible unless covalent as ionic is full separation of charge)