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THE LANGUAGE OF CHEMISTRY - Q&A

EXERCISE 1 (A)

1. What is a symbol? What information does it convey?
A symbol is the short form that stands for the atom of a specific element or the abbreviation used for the name of an element.
It conveys the following information:
1. It represents a specific element.
2. It represents one atom of that element.
3. It represents the atomic weight of the element (mass of one atom).

2. Why is the symbol S for sulphur, but Na for sodium and Si for silicon?
The symbol S is used for Sulphur because it is the first letter of its English name.
However, when the first letter of more than one element is the same (e.g., Sulphur, Sodium, Silicon all start with 'S'), two letters are used. For Sodium, the symbol 'Na' is derived from its Latin name "Natrium". For Silicon, the symbol 'Si' is derived from the first two letters of its English name to distinguish it from Sulphur.

3. If the symbol for Cobalt, Co, were written as CO, what would be wrong with it?
If Cobalt were written as CO, it would represent a molecule of the compound Carbon Monoxide (containing one Carbon atom and one Oxygen atom) rather than an atom of the element Cobalt. In a symbol, the second letter must always be small (lowercase) to indicate it belongs to the same element.

4. What do the following symbols stand for?
(a) H
(b) H₂
(c) 2H
(a) H stands for one atom of the element Hydrogen.
(b) H₂ stands for one molecule of Hydrogen (containing 2 atoms).
(c) 2H stands for two separate atoms of Hydrogen.

5. (a) Explain the terms 'valency' and 'variable valency'.
(b) How are the elements with variable valency named? Explain with an example.
(a) Valency: It is the combining capacity of an atom of an element. It is defined as the number of hydrogen atoms that combine with or displace one atom of that element. Alternatively, it is the number of electrons lost, gained, or shared by an atom during a chemical reaction.
Variable Valency: Certain elements exhibit more than one valency in different compounds. This phenomenon is called variable valency (e.g., Iron shows valency 2 and 3).

(b) Elements with variable valency are named using suffixes or Roman numerals:
1. Suffix method: The suffix "-ous" is used for the lower valency and "-ic" for the higher valency.
2. Roman Numeral method: The valency is written in Roman numerals in brackets after the name of the metal.
Example: Iron exhibits valencies 2 and 3.
- Fe²⁺ is named Ferrous or Iron(II).
- Fe³⁺ is named Ferric or Iron(III).

6. Give the formula and valency of:
(a) aluminate
(b) chromate
(c) aluminium
(d) cupric
(a) Aluminate: Formula: AlO₂^1-, Valency: 1
(b) Chromate: Formula: CrO₄^2-, Valency: 2
(c) Aluminium: Symbol: Al³⁺, Valency: 3
(d) Cupric: Symbol: Cu²⁺, Valency: 2

7. What is a chemical formula? What is the rule for writing a formula correctly?
A chemical formula is the symbolic representation of a molecule of a substance (element or compound). It denotes the number of atoms of each element present in one molecule.

Rule (Criss-Cross Method):
1. Write the symbols of the basic radical (positive ion) and acidic radical (negative ion) side by side.
2. Write the valency of each radical on top of its symbol.
3. Divide the valency numbers by their highest common factor (H.C.F.) to get a simple ratio.
4. Interchange the valencies and write them as subscripts to the right of the symbols. (Ignore '1').

8. What do you understand by the following terms?
(a) Acid radical
(b) Basic radical
(a) Acid radical: The electronegative radical (anion) contributed by an acid in the formation of a salt is called an acid radical. E.g., Chloride (Cl^-) in NaCl.
(b) Basic radical: The electropositive radical (cation) contributed by a base in the formation of a salt is called a basic radical. E.g., Sodium (Na⁺) in NaCl.

9. Match the following:
(a) Boric acid — (xvi) H₃BO₃
(b) Phosphoric acid — (xvii) H₃PO₄
(c) Nitrous acid — (xv) HNO₂
(d) Nitric acid — (xiv) HNO₃
(e) Sulphurous acid — (xiii) H₂SO₃
(f) Sulphuric acid — (xviii) H₂SO₄
(g) Hydrochloric acid — (xii) HCl
(h) Silica (sand) — (ii) SiO₂
(i) Caustic soda — (i) NaOH
(j) Caustic potash — (iv) KOH
(k) Washing soda — (iii) Na₂CO₃
(l) Baking soda — (vi) NaHCO₃
(m) Lime stone — (v) CaCO₃
(n) Water — (viii) H₂O
(o) Hydrogen sulphide — (vii) H₂S
(p) Ammonia — (xi) NH₃
(q) Phosphine — (ix) PH₃
(r) Methane — (x) CH₄

10. Select the basic and acidic radicals in the following compounds.
(a) MgSO₄
(b) (NH₄)₂SO₄
(c) Al₂(SO₄)₃
(d) ZnCO₃
(e) Mg(OH)₂
(a) Basic: Mg²⁺ (Magnesium), Acidic: SO₄^2- (Sulphate)
(b) Basic: NH₄⁺ (Ammonium), Acidic: SO₄^2- (Sulphate)
(c) Basic: Al³⁺ (Aluminium), Acidic: SO₄^2- (Sulphate)
(d) Basic: Zn²⁺ (Zinc), Acidic: CO₃^2- (Carbonate)
(e) Basic: Mg²⁺ (Magnesium), Acidic: OH^- (Hydroxide)

11. The valency of an element A is 3 and that of element B is 2. Write the formula of the compound formed by the combination of A and B.
Using the criss-cross method:
Element A valency: 3
Element B valency: 2
Interchanging valencies: A₂B₃
Formula: A₂B₃

12. Write chemical formula of the sulphate of Aluminium, Ammonium and Zinc.
1. Aluminium Sulphate: Al is 3+, Sulphate is SO₄^2-. Cross valencies: Al₂(SO₄)₃
2. Ammonium Sulphate: NH₄ is 1+, Sulphate is SO₄^2-. Cross valencies: (NH₄)₂SO₄
3. Zinc Sulphate: Zn is 2+, Sulphate is SO₄^2-. Ratio 2:2 simplifies to 1:1. Formula: ZnSO₄

13. Write the chemical names of the following compounds:
(a) Ca₃(PO₄)₂
(b) K₂CO₃
(c) K₂MnO₄
(d) Mn₃(BO₃)₂
(e) Mg(HCO₃)₂
(f) Na₄Fe(CN)₆
(g) Ba(ClO₃)₂
(h) Ag₂SO₃
(i) (CH₃COO)₂Pb
(j) Na₂SiO₃
(a) Calcium phosphate
(b) Potassium carbonate
(c) Potassium manganate
(d) Manganese borate
(e) Magnesium bicarbonate (or Magnesium hydrogen carbonate)
(f) Sodium ferrocyanide
(g) Barium chlorate
(h) Silver sulphite
(i) Lead acetate
(j) Sodium silicate

EXERCISE 1 (B)

1. Balance the following equations:

(a) Fe + H₂O → Fe₃O₄ + H₂
Balanced: 3Fe + 4H₂O → Fe₃O₄ + 4H₂

(b) Ca + N₂ → Ca₃N₂
Balanced: 3Ca + N₂ → Ca₃N₂

(c) Zn + KOH → K₂ZnO₂ + H₂
Balanced: Zn + 2KOH → K₂ZnO₂ + H₂

(d) Fe₂O₃ + CO → Fe + CO₂
Balanced: Fe₂O₃ + 3CO → 2Fe + 3CO₂

(e) PbO + NH₃ → Pb + H₂O + N₂
Balanced: 3PbO + 2NH₃ → 3Pb + 3H₂O + N₂

(f) Pb₃O₄ → PbO + O₂
Balanced: 2Pb₃O₄ → 6PbO + O₂

(g) PbS + O₂ → PbO + SO₂
Balanced: 2PbS + 3O₂ → 2PbO + 2SO₂

(h) S + H₂SO₄ → SO₂ + H₂O
Balanced: S + 2H₂SO₄ → 3SO₂ + 2H₂O

(i) S + HNO₃ → H₂SO₄ + NO₂ + H₂O
Balanced: S + 6HNO₃ → H₂SO₄ + 6NO₂ + 2H₂O

(j) MnO₂ + HCl → MnCl₂ + H₂O + Cl₂
Balanced: MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂

(k) C + H₂SO₄ → CO₂ + H₂O + SO₂
Balanced: C + 2H₂SO₄ → CO₂ + 2H₂O + 2SO₂

(l) KOH + Cl₂ → KCl + KClO + H₂O
Balanced: 2KOH + Cl₂ → KCl + KClO + H₂O

(m) NO₂ + H₂O → HNO₂ + HNO₃
Balanced: 2NO₂ + H₂O → HNO₂ + HNO₃

(n) Pb₃O₄ + HCl → PbCl₂ + H₂O + Cl₂
Balanced: Pb₃O₄ + 8HCl → 3PbCl₂ + 4H₂O + Cl₂

(o) H₂O + Cl₂ → HCl + O₂
Balanced: 2H₂O + 2Cl₂ → 4HCl + O₂

(p) NaHCO₃ → Na₂CO₃ + H₂O + CO₂
Balanced: 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂

(q) HNO₃ + H₂S → NO₂ + H₂O + S
Balanced: 2HNO₃ + H₂S → 2NO₂ + 2H₂O + S

(r) P + HNO₃ → NO₂ + H₂O + H₃PO₄
Balanced: P + 5HNO₃ → 5NO₂ + H₂O + H₃PO₄

EXERCISE 1 (C)

1. Fill in the blanks:
(a) Dalton used symbol circle [O] for oxygen circle with a dot for hydrogen.
(b) Symbol represents one atom(s) of an element.
(c) Symbolic expression for a molecule is called chemical formula (or molecular formula).
(d) Sodium chloride has two radicals. Sodium is a basic radical while chloride is a acidic radical.
(e) Valency of carbon in CH₄ is 4, in C₂H₆ 4, in C₂H₄ 4 and in C₂H₂ is 4.
(f) Valency of Iron in FeCl₂ is 2 and in FeCl₃ it is 3.
(g) Formula of iron (III) carbonate is Fe₂(CO₃)₃.

2. Complete the following table.
Magnesium: MgCl₂, Mg(NO₃)₂, MgSO₄, MgCO₃, Mg(OH)₂, Mg₃(PO₄)₂
Sodium (Na⁺): NaCl, NaNO₃, Na₂SO₄, Na₂CO₃, NaOH, Na₃PO₄
Zinc (Zn²⁺): ZnCl₂, Zn(NO₃)₂, ZnSO₄, ZnCO₃, Zn(OH)₂, Zn₃(PO₄)₂
Silver (Ag⁺): AgCl, AgNO₃, Ag₂SO₄, Ag₂CO₃, AgOH, Ag₃PO₄
Ammonium (NH₄⁺): NH₄Cl, NH₄NO₃, (NH₄)₂SO₄, (NH₄)₂CO₃, NH₄OH, (NH₄)₃PO₄
Calcium (Ca²⁺): CaCl₂, Ca(NO₃)₂, CaSO₄, CaCO₃, Ca(OH)₂, Ca₃(PO₄)₂
Iron (II) (Fe²⁺): FeCl₂, Fe(NO₃)₂, FeSO₄, FeCO₃, Fe(OH)₂, Fe₃(PO₄)₂
Potassium (K⁺): KCl, KNO₃, K₂SO₄, K₂CO₃, KOH, K₃PO₄

3. Sodium chloride reacts with silver nitrate to produce silver chloride and sodium nitrate
(a) Write the equation.
(b) Check whether it is balanced, if not balance it.
(c) Find the weights of reactants and products.
(d) State the law which this equation satisfies.
(a) NaCl + AgNO₃ → AgCl + NaNO₃
(b) The equation is already balanced (1 Na, 1 Cl, 1 Ag, 1 N, 3 O on both sides).
(c) Atomic masses: Na=23, Cl=35.5, Ag=108, N=14, O=16.
Reactants weight:
NaCl = 23 + 35.5 = 58.5 g
AgNO₃ = 108 + 14 + (16×3) = 170 g
Total Reactants = 58.5 + 170 = 228.5 g
Products weight:
AgCl = 108 + 35.5 = 143.5 g
NaNO₃ = 23 + 14 + 48 = 85 g
Total Products = 143.5 + 85 = 228.5 g
(d) This satisfies the Law of Conservation of Mass (Matter is neither created nor destroyed).

4. What information does the following chemical equations convey?
(a) Zn + H₂SO₄ → ZnSO₄ + H₂
(b) Mg + 2HCl → MgCl₂ + H₂
(a) It conveys that:
- One atom of Zinc reacts with one molecule of Sulphuric acid.
- The products are one molecule of Zinc Sulphate and one molecule of Hydrogen gas.
- Zinc displaces hydrogen from the acid.
(b) It conveys that:
- One atom of Magnesium reacts with two molecules of Hydrochloric acid.
- The products are one molecule of Magnesium Chloride and one molecule of Hydrogen gas.
- Quantitative ratio: 24 parts by weight of Mg react with 73 parts by weight of HCl.

5. (a) What are poly-atomic ions? Give two examples.
(b) Name the fundamental law that is involved in every equation.
(a) Poly-atomic ions (or compound radicals) are ions composed of two or more different atoms acting as a single unit with a net charge.
Examples: Sulphate (SO₄^2-), Ammonium (NH₄⁺).
(b) The Law of Conservation of Mass.

6. What is the valency of:
(a) fluorine in CaF₂
(b) sulphur in SF₆
(c) phosphorus in PH₃
(d) carbon in CH₄
(e) nitrogen in the following compounds: (i) N₂O₃ (ii) N₂O₅ (iii) NO₂ (iv) NO
(a) 1 (Calcium is 2, so F must be 1 to balance CaF₂).
(b) 6 (Fluorine is 1, so S must be 6 to balance SF₆).
(c) 3 (Hydrogen is 1, so P must be 3 to balance PH₃).
(d) 4 (Hydrogen is 1, so C must be 4 to balance CH₄).
(e) Nitrogen valency:
(i) N₂O₃: 3 (From 2x = 3*2 => 2x=6 => x=3)
(ii) N₂O₅: 5 (From 2x = 5*2 => 2x=10 => x=5)
(iii) NO₂: 4 (From x = 2*2 => x=4)
(iv) NO: 2 (From x = 1*2 => x=2)

7. Why should an equation be balanced? Explain with the help of a simple equation.
An equation should be balanced to comply with the Law of Conservation of Mass, which states that matter is neither created nor destroyed during a chemical reaction. The total number of atoms of each element on the reactant side must equal the total number of atoms on the product side.
Example: H₂ + O₂ → H₂O (Unbalanced - O is not equal).
Balanced: 2H₂ + O₂ → 2H₂O (Here, 4 H atoms and 2 O atoms are on both sides).

8. Write the balanced chemical equations of the following reactions.
(a) 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
(b) 2KHCO₃ + H₂SO₄ → K₂SO₄ + 2CO₂ + 2H₂O
(c) Fe + H₂SO₄ → FeSO₄ + H₂
(d) Cl₂ + SO₂ + 2H₂O → H₂SO₄ + 2HCl
(e) 2AgNO₃ → 2Ag + 2NO₂ + O₂ (Decomposition by heat)
(f) 3Cu + 8HNO₃ → 3Cu(NO₃)₂ + 2NO + 4H₂O
(g) 4NH₃ + 5O₂ → 4NO + 6H₂O
(h) BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
(i) 2ZnS + 3O₂ → 2ZnO + 2SO₂
(j) Al₄C₃ + 12H₂O → 4Al(OH)₃ + 3CH₄
(k) 4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂
(l) 2KMnO₄ + 16HCl → 2KCl + 2MnCl₂ + 5Cl₂ + 8H₂O
(m) Al₂(SO₄)₃ + 6NaOH → 2Al(OH)₃ + 3Na₂SO₄ (If excess NaOH: Al(OH)₃ + NaOH → NaAlO₂ + 2H₂O. The prompt asks for sodium meta aluminate).
Full reaction for (m) producing meta aluminate: Al₂(SO₄)₃ + 8NaOH → 2NaAlO₂ + 3Na₂SO₄ + 4H₂O
(n) 2Al + 2NaOH + 2H₂O → 2NaAlO₂ + 3H₂
(o) 2K₂Cr₂O₇ + 8H₂SO₄ → 2K₂SO₄ + 2Cr₂(SO₄)₃ + 8H₂O + 3O₂
(p) K₂Cr₂O₇ + 14HCl → 2KCl + 2CrCl₃ + 7H₂O + 3Cl₂
(q) S + 6HNO₃ → H₂SO₄ + 6NO₂ + 2H₂O
(r) 2NaCl + MnO₂ + 2H₂SO₄ → Na₂SO₄ + MnSO₄ + 2H₂O + Cl₂ (or NaHSO₄ depending on temp. The prompt says Sodium Hydrogen Sulphate).
Balanced for NaHSO₄: NaCl + MnO₂ + 2H₂SO₄ → NaHSO₄ + MnSO₄ + 2H₂O + Cl₂ (Wait, stoichiometry: 2NaCl + MnO₂ + 3H₂SO₄ -> 2NaHSO₄ + MnSO₄ + 2H₂O + Cl₂. Let's check: Cl: 2->2, Na: 2->2, Mn: 1->1, S: 3->3, H: 6 -> 2+4=6, O: 2+12=14 -> 8+4+2=14). Correct.

9. (a) Define atomic mass unit.
(b) Calculate the molecular mass of the following:
(i) CuSO₄.5H₂O
(ii) (NH₄)₂CO₃
(iii) (NH₂)₂CO
(iv) Mg₃N₂
Given atomic mass of Cu = 63.5, H = 1, O = 16, C = 12, N = 14, Mg = 24, S = 32
(a) Atomic mass unit (amu) is defined as exactly 1/12th the mass of one atom of carbon-12 isotope.
(b) Calculations:
(i) CuSO₄.5H₂O = 63.5 + 32 + (4×16) + 5(2×1 + 16)
= 63.5 + 32 + 64 + 5(18)
= 159.5 + 90 = 249.5
(ii) (NH₄)₂CO₃ = 2(14 + 4×1) + 12 + 3×16
= 2(18) + 12 + 48
= 36 + 60 = 96
(iii) (NH₂)₂CO (Urea) = 2(14 + 2×1) + 12 + 16
= 2(16) + 28
= 32 + 28 = 60
(iv) Mg₃N₂ = 3(24) + 2(14)
= 72 + 28 = 100

10. Choose the correct answer from the options given below.
(a) Modern atomic symbols are based on the method proposed by
(i) Bohr (ii) Dalton (iii) Berzelius (iv) Alchemist
(b) The number of carbon atoms in a hydrogen carbonate radical is
(i) one (ii) two (iii) three (iv) four
(c) The formula of iron (III) sulphate is
(i) Fe₃SO₄ (ii) Fe(SO₄)₃ (iii) Fe₂(SO₄)₃ (iv) FeSO₄
(d) In water, the hydrogen-to-oxygen mass ratio is
(i) 1:8 (ii) 1:16 (iii) 1:32 (iv) 1:64
(e) The formula of sodium carbonate is Na₂CO₃ and that of calcium hydrogen carbonate is
(i) CaHCO₃ (ii) Ca(HCO₃)₂ (iii) Ca₂HCO₃ (iv) Ca(HCO₃)₃
(a) (iii) Berzelius
(b) (i) one (Formula is HCO₃^-)
(c) (iii) Fe₂(SO₄)₃
(d) (i) 1:8 (Mass of 2H = 2, Mass of O = 16. Ratio 2:16 = 1:8)
(e) (ii) Ca(HCO₃)₂ (Ca is +2, HCO₃ is -1)

11. Correct the following statements
(a) A molecular formula represents an element.
(b) Molecular formula of water (H₂O) represents 9 parts by mass of water.
(c) A balanced equation obeys the law of conservation of mass and so does an unbalanced equation.
(d) A molecule of an element is always monoatomic.
(e) CO and Co both represent cobalt.
(a) A molecular formula represents a molecule of an element or a compound.
(b) Molecular formula of water (H₂O) represents 18 parts by mass of water (2 + 16 = 18).
(c) Only a balanced equation obeys the law of conservation of mass; an unbalanced equation does not.
(d) A molecule of an element can be monoatomic, diatomic, or polyatomic (e.g., O₂, P₄).
(e) Co represents Cobalt, while CO represents Carbon Monoxide.

12. Calculate the relative molecular masses of:
(a) CHCl₃
(b) (NH₄)₂Cr₂O₇
(c) CuSO₄.5H₂O
(d) (NH₄)₂SO₄
(e) CH₃COONa
(f) Potassium chlorate
(g) Ammonium chloroplatinate (NH₄)₂PtCl₆
(Note: Use standard atomic masses: C=12, H=1, Cl=35.5, N=14, Cr=52, Cu=63.5, S=32, Na=23, K=39, Pt=195)
(a) CHCl₃ = 12 + 1 + 3(35.5) = 13 + 106.5 = 119.5
(b) (NH₄)₂Cr₂O₇ = 2(14+4) + 2(52) + 7(16) = 36 + 104 + 112 = 252
(c) CuSO₄.5H₂O = 63.5 + 32 + 64 + 5(18) = 159.5 + 90 = 249.5
(d) (NH₄)₂SO₄ = 2(18) + 32 + 64 = 36 + 96 = 132
(e) CH₃COONa = 12 + 3(1) + 12 + 16 + 16 + 23 = 15 + 12 + 32 + 23 = 82
(f) KClO₃ = 39 + 35.5 + 3(16) = 74.5 + 48 = 122.5
(g) (NH₄)₂PtCl₆ = 2(18) + 195 + 6(35.5) = 36 + 195 + 213 = 444

13. Give the empirical formula of:
(a) Benzene (C₆H₆)
(b) Glucose (C₆H₁₂O₆)
(c) Acetylene (C₂H₂)
(d) Acetic acid (CH₃COOH) = C₂H₄O₂
(a) Ratio 6:6 = 1:1. Empirical Formula: CH
(b) Ratio 6:12:6 = 1:2:1. Empirical Formula: CH₂O
(c) Ratio 2:2 = 1:1. Empirical Formula: CH
(d) Ratio 2:4:2 = 1:2:1. Empirical Formula: CH₂O

14. Find the percentage mass of water in the Epsom salt MgSO₄.7H₂O.
Molecular Mass of MgSO₄.7H₂O:
Mg(24) + S(32) + 4O(64) + 7(H₂O)(18)
= 24 + 32 + 64 + 126 = 246
Mass of Water (7H₂O) = 7 × 18 = 126
Percentage of water = (126 / 246) × 100 = 51.22%

15. Calculate the percentage of phosphorus in:
(a) Calcium hydrogen phosphate Ca(H₂PO₄)₂
(b) Calcium phosphate Ca₃(PO₄)₂
(a) Ca(H₂PO₄)₂:
Mass = 40 + 2[2(1) + 31 + 4(16)] = 40 + 2[2 + 31 + 64] = 40 + 2[97] = 40 + 194 = 234
Mass of P = 2 × 31 = 62
% P = (62 / 234) × 100 = 26.5%
(b) Ca₃(PO₄)₂:
Mass = 3(40) + 2[31 + 64] = 120 + 2(95) = 120 + 190 = 310
Mass of P = 2 × 31 = 62
% P = (62 / 310) × 100 = 20%

16. Calculate the percentage composition of each element in Potassium chlorate, KClO₃.
Molecular Mass of KClO₃ = 39 (K) + 35.5 (Cl) + 3×16 (O)
= 39 + 35.5 + 48 = 122.5
% K = (39 / 122.5) × 100 = 31.83%
% Cl = (35.5 / 122.5) × 100 = 28.98%
% O = (48 / 122.5) × 100 = 39.18%

17. Urea is a very important nitrogenous fertilizer. Its formula is CON₂H₄. Calculate the percentage of carbon in urea.
Molecular Mass of Urea (CON₂H₄) = 12 (C) + 16 (O) + 2×14 (N) + 4×1 (H)
= 12 + 16 + 28 + 4 = 60
Mass of Carbon = 12
% Carbon = (12 / 60) × 100 = 20%

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Quick Review Flashcards - Click to flip and test your knowledge!

Question

What is the definition of a chemical 'symbol'?

Answer

A short form or abbreviation used to represent a specific element or one atom of an element.

Question

In addition to representing an element, what quantitative value does a symbol represent?

Answer

The weight of the element equal to its atomic weight relative to $1/12$th the mass of a carbon $C^{12}$ atom.

Question

Which scientist suggested using figurative symbols for atoms of elements in 1807?

Answer

John Dalton

Question

In 1814, _____ suggested a system using the first letter (and sometimes a second small letter) of an element's name as its symbol.

Answer

Berzelius

Question

Symbol/Latin Name: Copper

Answer

Cuprum ($Cu$)

Question

Symbol/Latin Name: Potassium

Answer

Kalium ($K$)

Question

Symbol/Latin Name: Iron

Answer

Ferrum ($Fe$)

Question

Symbol/Latin Name: Mercury

Answer

Hydrargyrum ($Hg$)

Question

Symbol/Latin Name: Lead

Answer

Plumbum ($Pb$)

Question

Symbol/Latin Name: Silver

Answer

Argentum ($Ag$)

Question

Symbol/Latin Name: Sodium

Answer

Natrium ($Na$)

Question

Symbol/Latin Name: Gold

Answer

Aurum ($Au$)

Question

How is 'valency' defined in terms of hydrogen combination?

Answer

The number of hydrogen atoms which can combine with or displace one atom of the element or radical to form a compound.

Question

The valency of all metals and hydrogen is considered _____, while the valency of non-metals is taken as _____.

Answer

positive; negative

Question

Definition: Valency of a metal

Answer

The number of electrons lost per atom of the metal.

Question

Definition: Valency of a non-metal

Answer

The number of electrons gained per atom of the non-metal.

Question

What is 'variable valency'?

Answer

A property where certain elements exhibit more than one valency.

Question

What is the primary reason an atom exhibits variable valency?

Answer

Electrons are lost from the penultimate shell in addition to the valence shell.

Question

Which two common valencies are exhibited by Copper ($Cu$)?

Answer

$1+$ (Cuprous) and $2+$ (Cupric)

Question

Which two common valencies are exhibited by Iron ($Fe$)?

Answer

$2+$ (Ferrous) and $3+$ (Ferric)

Question

Term: Radical

Answer

Definition: An atom or group of atoms of the same or different elements that behaves as a single unit and shows a valency.

Question

Why are radicals typically highly reactive and short-lived?

Answer

They contain at least one unpaired valence electron, making them unstable.

Question

In which layer of the atmosphere are atmospheric radicals like hydroxyl primarily found?

Answer

The lower troposphere

Question

What are two potential human health effects of atmospheric radicals?

Answer

Respiratory and cardiovascular (heart) problems.

Question

Concept: Atomicity

Answer

The number of atoms present in one molecule of an element.

Question

In a chemical formula, where is the atomicity of a molecular element written?

Answer

As a subscript after the symbol of the element.

Question

Name/Formula: Ammonium radical

Answer

$NH_{4}^{1+}$

Question

Name/Formula: Carbonate radical

Answer

$CO_{3}^{2-}$

Question

Name/Formula: Phosphate radical

Answer

$PO_{4}^{3-}$

Question

Name/Formula: Nitrate radical

Answer

$NO_{3}^{1-}$

Question

Name/Formula: Sulphate radical

Answer

$SO_{4}^{2-}$

Question

Name/Formula: Hydroxide radical

Answer

$OH^{1-}$

Question

Name/Formula: Bicarbonate (Hydrogen carbonate) radical

Answer

$HCO_{3}^{1-}$

Question

What are the three essential components of the definition of a 'compound'?

Answer

A pure substance composed of two or more elements combined chemically in a fixed proportion.

Question

How do the properties of a compound like water ($H_{2}O$) compare to its constituent elements (hydrogen and oxygen)?

Answer

The properties are entirely different from those of the constituent elements.

Question

Compounds are always _____ in nature, meaning their composition is uniform throughout.

Answer

homogeneous

Question

Why can the components of a compound only be separated by chemical means?

Answer

Because the elements are chemically combined and do not retain their original physical properties.

Question

What is the chemical formula for Nitric acid?

Answer

$HNO_{3}$

Question

What is the chemical formula for Acetic acid?

Answer

$CH_{3}COOH$

Question

What is the common name for the salt Sodium chloride ($NaCl$)?

Answer

Rock salt

Question

What is the chemical name and formula for Epsom salt?

Answer

Magnesium sulphate heptahydrate ($MgSO_{4} \cdot 7H_{2}O$)

Question

What is the chemical name and formula for Blue vitriol?

Answer

Copper [II] sulphate pentahydrate ($CuSO_{4} \cdot 5H_{2}O$)

Question

What is the chemical formula for Methane?

Answer

$CH_{4}$

Question

What is the chemical formula for Ethanol?

Answer

$C_{2}H_{5}OH$

Question

In the 'criss-cross' method of writing formulae, what is the third step?

Answer

Interchange the valency numbers of the atoms or radicals and write them as subscripts on the lower right.

Question

When naming a compound containing a metal and a non-metal, which is written first?

Answer

The metal.

Question

What suffix is given to the non-metal in a binary compound of a metal and a non-metal?

Answer

-ide

Question

In compounds containing only two non-metals, what do the prefixes mono-, di-, and tri- denote?

Answer

The number of atoms of that specific non-metal in the molecule.

Question

Between the oxy-anions 'chlorate' and 'chlorite', which one contains more oxygen atoms?

Answer

Chlorate

Question

What does the prefix 'hypo-' signify in naming oxy-compounds like 'Potassium hypo-chlorite'?

Answer

It signifies the compound with the least amount of oxygen in the series.

Question

A shorthand form for a chemical change that represents reactants and products using symbols and formulae is a _____.

Answer

chemical equation

Question

In a chemical equation, what do the symbols $(s)$, $(l)$, $(g)$, and $(aq)$ represent?

Answer

The state of matter: solid, liquid, gas, and aqueous (solution in water).

Question

List two pieces of information that a chemical equation does NOT provide.

Answer

The concentration of reactants/products and the speed (rate) of the reaction.

Question

What is a 'balanced' chemical equation?

Answer

An equation where the number of atoms of each element is the same on both the reactant and product sides.

Question

Why must chemical equations be balanced?

Answer

To comply with the Law of Conservation of Matter, stating matter is neither created nor destroyed.

Question

Which balancing method involves counting atoms and equalising them by trial, often used for simple equations?

Answer

The Hit and Trial Method

Question

The method of balancing complex reactions by breaking them into individual steps is known as the _____.

Answer

Partial Equation Method

Question

What is the definition of Relative Atomic Mass ($RAM$)?

Answer

The number of times one atom of an element is heavier than $1/12$th the mass of a carbon $C^{12}$ atom.

Question

What is the standard isotope used as a reference for relative atomic and molecular masses?

Answer

Carbon-12 ($C^{12}$)

Question

How is the Relative Molecular Mass ($RMM$) of a compound calculated?

Answer

By adding together the relative atomic masses ($RAM$) of all the atoms present in the molecule.