(a) Consider the following atoms: \(^R_T\)X; \(^S_T\)X.
(i) State the phenomenon exhibited by the two atoms.
(ii) What is the difference between the atoms?
(iii) Give two examples of elements that exhibit the phenomenon stated in (ai)
(iv) lf T is 17, write the electron configuration of the element
(b)(i) State two differences between metals and-non-metals with respect to their:
I. physical properties;
2. chemical properties.
(ii) Give one example of each for the following compounds:
I. an amphoteric oxide;
II. a hydride which evolves hydrogen when reacted with water;
Ill. a trioxocarbonate (IV) salt which is readily decomposed on heating;
IV. a chloride salt which is readily hydrolyzed in water.
(c)(i) State three characteristic properties of transition metals.
(ii) Write the electron configuration of \(_{30}Zn\)
(iii.) Explain briefly why zinc is not considered as a typical transition element.
(d) Consider the reaction represented by the following equation:- Na\(_2\)CO\(_{3(aq)}\) + MgCl\(_{2(aq)}\) —-> 2NaCl\(_{(aq)}\) + MgCO\(_{3(aq)}\). Calculate the mass of sodium trioxocarbonate (IV) needed to produce 3.36 of magnesium trioxocarbonate (IV). [C = 12.0, O = 16.0, Na = 23.0, Mg = 24:0 ]
Explanation
(a)(i) Isotopy
(ii) They have different mass numbers or number of neutrons.
(iii) —Hydrogen, —Chlorine. —Carbon, —Oxygen.
(iv) 1 S\(^2\)2S\(^2\)2P\(^62\)3S\(^2\)3P\(^5\)
(b)(i) 1. DIFFERENCES IN PHYSICAL PROPERTIES
|
METALS |
NON — METALS |
|
Good conductors of heat and electricity |
Poor conductors of heat and electricity |
|
Malleable - can be beaten into thin sheets |
Not malleable / brittle |
|
Ductile — can be stretched into wire |
Non ductile / biittle |
|
Possess metallic luster |
Do not possess metallic luster |
|
Are sonorous |
Not sonorous |
|
Solid at room temperature except mercury / high melting point |
Solids, liquids or gases at room temperature / low melting point
|
2. DIFFERENCES IN CHEMICAL PROPERTIES
|
METALS NON |
METALS |
|
Lose their valence electrons easily / ionize by electron loss |
Gain or share valence electrons easily / ionize by electron gain |
|
Form oxides that are basic / amphoteric |
Form oxides that are acidic / neutral |
|
Are good reducing agents |
Are good oxidizing agents |
|
Have lower electro negativities |
Have higher electro negativities |
|
Have low ionization energy |
Have high ionization energy |
|
(Some reactive metals) react with dilute acids to give off hydrogen |
Do not react with dilute acids to give off hydrogen. |
(ii) (l) BeO, Al\(_2\)O\(_3\), ZnO, SnO\(_2\), PbO, PbO\(_2\)
(II) LiH, NaH, KH, CaCO\(_3\) MgH\(_2\)
(III) Li\(_2\)CO\(_3\), BeCO\(_3\), MgCO\(_3\), CaCO\(_3\), ZnCO\(_3\), PbCO\(_3\)
(IV) AlCl\(_3\), MgCl\(_2\), PCl\(_3\), SiCl\(_4\), NH\(_4\)Cl
(c)(i) - form coloured compounds / ions, - exhibit variable oxidation states. - form complex compounds / ion. - have magnetic properties (paramagnetism). - have catalytic properties.
(ii) —> 1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^6\)3d\(^{10}\)4s\(^2\) are fully filled
(d) Mr(MgCO\(_3\)) = 24 + 12 + (16 x 3) 84
Mr(Na\(_2\)CO\(_3\)) = (23 x 2) +12 + (3 x 16) = 106
moles of MgCO\(_3\) = \(\frac{3.36}{84}\) = 0.04
moles of Na\(_2\)CO\(_3\) = moles of MgCO\(_3\) = 0.04
mass of NaCO\(_3\) = 0.04 x106 = 4.24g
OR
Mr(MgCO\(_3\)) = 24 + 12 + (1 6 x 3) 84
Mr(Na\(_2\)CO\(_3\)) = (23 x 2) +12 + (3 x 16) = 106
84g of MgCO\(_3\) produced from 10\(^6\)g Na\(_2\)CO\(_3\)
3.36g of MgCO\(_3\) will be produced
From 106 x \(\frac{3.36}{84}\) = 4.24g