Module 3 - Group 2 Flashcards
The reaction of barium with bromine is more vigorous than the reaction of calcium with bromine (3)
Barium has a greater atomic radius that calcium
Barium has more shells/ Barium has more shielding
Outer electrons in Ba is less attracted to nucleus
Easier to remove electrons in Ba
Describe two reactions which would be different if the student had used calcium in place of strontium (2)
Less vigorous bubbling
Solutions has lower pH
Dissolves more slowly
Reactivity of the group 2 elements Mg-Ba increases down the group. Explain why (2)
- Atomic radius increases
Outer electrons have less attraction - Ionisation energy decreases
Identify a compound of calcium that could be used to convert a soil pH from 5.8 to 7.5 (1)
Calcium hydroxide OR
Calcium oxide
Describe what is seen when Mg ribbon is added to an excess of HCl (2)
Bubbles/ Fizzes
Solution is formed
Describe an explain the trend, down the group in the reactivity of the group 2 metals with water (5)
1.Reactivity increases
2.Atomic radius increases
3.More shielding
4.Increased nuclear chage
5.Easier to remove electrons/ Ionisation energy decreases
A student prepared an aqueous solution of calcium chloride by reacting calcium with hydrochloric acid. Ca(s) + 2HCl(aq) → CaCl2(aq) + H2(g)
Using oxidation numbers, show that this is a redox reaction (2)
Ca changed from 0 to +2
H has changed from +1 to 0
Describe the structure and bonding in magnesium. (2)
- (giant) lattice of (Mg2+) cations / (giant) lattice of (Mg) atoms
- (Electrostatic) attractions between cations / Mg2+ ions / nuclei and delocalised electrons
Explain why the first ionisation energy of the Group 2 elements decreases down the group. (2)
- The outer electron is in a higher (energy) level / there is an increase in shielding / the atoms get larger / more shells
- There is a weaker attraction between the nucleus and the outer electron.
Explain why the third ionisation energy of magnesium is much higher than the second ionisation energy of magnesium. (2)
- The electron is removed from 2p sub-shell / 2nd energy level / lower energy level / sub-shell that is closer to the nucleus
- (Electron being removed is) less shielded (than 3s)
Which statement is correct?
A. Magnesium reacts with steam to give magnesium oxide as one of the products.
B. Magnesium acts as an oxidising agent in the extraction of titanium.
C. Magnesium has a lower melting point than sodium.
D. Magnesium hydroxide is very soluble in water.
A. Magnesium oxide is a product when magnesium reacts with steam.
Uses of:
Ba(SO)4 ?
Ca(OH)2 ?
Mg(OH)2 and CaCO3 ?
Ba(SO)4 in medicine to produce an X-ray image
Ca(OH)2 in agriculture to neutralise acid
soils
Mg(OH)2 and CaCO3 as ‘antacids’ in treating
indigestion.
Explain why the melting point of magnesium is higher than the melting point of sodium. (2)
- Mg2+ has a higher charge than Na+ / Mg has more delocalised electrons than Na / Mg has a higher nuclear charge
- Stronger attraction to delocalised sea of electrons / stronger metallic bonding
What is the correct observation when barium metal is added to an excess of water?
A. Forms a colourless solution only
B. Forms a colourless solution and effervesces
C. Forms a white precipitate only
D. Forms a white precipitate and effervesces
B
(a) Explain why the third ionisation energy of beryllium is much higher than the second ionisation energy of beryllium. (3)
- Electron is removed from 1(s) (rather than 2(s))
- Lower in energy (than 2s)/Less/No shielding/closer to the nucleus
- Stronger attraction between nucleus and outer electron
Magnesium reacts slowly with cold water but rapidly with steam.
Compare these reactions, in terms of the products formed.
You should identify one similarity in, and one difference between, these reactions (3)
Similarity: produce hydrogen/ produce Mg2+ compounds
Difference: magnesium oxide formed with steam and magnesium hydroxide formed with (cold) water
A student is provided with separate unlabelled samples of four different solutions for analysis.
The four solutions are known to be ammonium nitrate, potassium sulfate, sodium carbonate and magnesium nitrate, but the student does not know which sample is which.
Outline a series of test-tube reactions that the student can use to identify each of these solutions and its ionic eq. (6)
1a: add NaOH
add NaOH (and warm) then hold damp red litmus at mouth of tube
add nitric acid/hydrochloric acid
add acidified BaCl2
2a: Mg(NO3)2 will give a white ppt with NaOH
red litmus will turn blue for NH4NO3
with NaOH Na2CO3 will effervesce with acid/gas formed turns limewater cloudy
K2SO4 will give a white ppt with BaCl2
3a: Mg2+ + 2 OH- → Mg(OH)2
3b: NH4+ + OH- → NH3 + H2O
3c: CO32- + 2 H+ → CO2 + H2O
3d: SO42- + Ba2+ → BaSO4
