41 Defining the Atom Section Review Answer Key

1 .

The starting materials consist of 1 green sphere and two purple spheres. The products consist of two green spheres and two purple spheres. This violates Dalton'south postulate that that atoms are not created during a chemic change, but are just redistributed.

three .

This statement violates Dalton's fourth postulate: In a given compound, the numbers of atoms of each type (and thus as well the pct) always have the aforementioned ratio.

five .

Dalton originally idea that all atoms of a detail chemical element had identical properties, including mass. Thus, the concept of isotopes, in which an chemical element has dissimilar masses, was a violation of the original idea. To account for the existence of isotopes, the second postulate of his atomic theory was modified to country that atoms of the same element must have identical chemical properties.

7 .

Both are subatomic particles that reside in an cantlet's nucleus. Both take approximately the same mass. Protons are positively charged, whereas neutrons are uncharged.

9 .

(a) The Rutherford cantlet has a small, positively charged nucleus, so about α particles will laissez passer through empty space far from the nucleus and exist undeflected. Those α particles that pass near the nucleus will exist deflected from their paths due to positive-positive repulsion. The more straight toward the nucleus the α particles are headed, the larger the deflection bending will be. (b) Higher-free energy α particles that pass near the nucleus will notwithstanding undergo deflection, simply the faster they travel, the less the expected angle of deflection. (c) If the nucleus is smaller, the positive charge is smaller and the expected deflections are smaller—both in terms of how closely the α particles laissez passer by the nucleus undeflected and the bending of deflection. If the nucleus is larger, the positive charge is larger and the expected deflections are larger—more α particles will be deflected, and the deflection angles will exist larger. (d) The paths followed by the α particles lucifer the predictions from (a), (b), and (c).

11 .

(a) ¹³³Cs⁺; (b) ¹²⁷I⁻; (c) ³¹P³⁻; (d) ⁵⁷Co³⁺

xiii .

(a) Carbon-12, ¹²C; (b) This atom contains six protons and six neutrons. There are six electrons in a neutral ¹²C cantlet. The internet charge of such a neutral atom is zero, and the mass number is 12. (c) The preceding answers are right. (d) The atom will exist stable since C-12 is a stable isotope of carbon. (e) The preceding answer is correct. Other answers for this exercise are possible if a unlike element of isotope is chosen.

15 .

(a) Lithium-6 contains iii protons, three neutrons, and three electrons. The isotope symbol is ^sixLi or ${}_3^6\text{Li}.$ (b) ⁶Li⁺ or ${}_3^6{\text{Li}}^{+}$

17 .

(a) Iron, 26 protons, 24 electrons, and 32 neutrons; (b) iodine, 53 protons, 54 electrons, and 74 neutrons

19 .

(a) 3 protons, iii electrons, iv neutrons; (b) 52 protons, 52 electrons, 73 neutrons; (c) 47 protons, 47 electrons, 62 neutrons; (d) 7 protons, 7 electrons, viii neutrons; (due east) 15 protons, fifteen electrons, sixteen neutrons

21 .

Let the states use neon equally an example. Since there are three isotopes, there is no way to be sure to accurately predict the abundances to make the total of 20.xviii amu average atomic mass. Allow us judge that the abundances are 9% Ne-22, 91% Ne-20, and merely a trace of Ne-21. The average mass would be xx.eighteen amu. Checking the nature'southward mix of isotopes shows that the abundances are 90.48% Ne-20, 9.25% Ne-22, and 0.27% Ne-21, so our guessed amounts accept to be slightly adjusted.

25 .

Turkey source: 20.three% (of 10.0129 amu isotope); U.s.a. source: 19.one% (of 10.0129 amu isotope)

27 .

The symbol for the element oxygen, O, represents both the element and one atom of oxygen. A molecule of oxygen, O_ii, contains 2 oxygen atoms; the subscript 2 in the formula must be used to distinguish the diatomic molecule from two single oxygen atoms.

29 .

(a) molecular CO₂, empirical CO₂; (b) molecular C₂H_ii, empirical CH; (c) molecular C₂H_iv, empirical CH_two; (d) molecular H_iiSo_iv, empirical H_twoSO₄

31 .

(a) C_ivH₅North₂O; (b) C₁₂H₂₂O_xi; (c) HO; (d) CH₂O; (eastward) C₃H_fourO₃

35 .

(a) ethanol

(b) methoxymethane, more commonly known equally dimethyl ether

(c) These molecules have the same chemic composition (types and number of atoms) but dissimilar chemical structures. They are structural isomers.

37 .

Employ the molecular formula to discover the molar mass; to obtain the number of moles, divide the mass of compound by the molar mass of the compound expressed in grams.

39 .

Formic acrid. Its formula has twice as many oxygen atoms as the other ii compounds (one each). Therefore, 0.60 mol of formic acid would exist equivalent to i.20 mol of a chemical compound containing a single oxygen cantlet.

41 .

The 2 masses have the same numerical value, but the units are unlike: The molecular mass is the mass of 1 molecule while the molar mass is the mass of half-dozen.022 $\times$ x²³ molecules.

43 .

(a) 256.48 g/mol; (b) 72.150 g mol^−one; (c) 378.103 g mol⁻¹; (d) 58.080 g mol⁻¹; (east) 180.158 g mol^−ane

45 .

(a) 197.382 g mol⁻¹; (b) 257.163 g mol⁻¹; (c) 194.193 chiliad mol⁻¹; (d) threescore.056 chiliad mol⁻ⁱ; (east) 306.464 g mol⁻¹

47 .

(a) 0.819 g;
(b) 307 g;
(c) 0.23 g;
(d) one.235 $\times$ 10⁶ one thousand (1235 kg);
(e) 765 yard

49 .

(a) 99.41 g;
(b) two.27 grand;
(c) 3.5 g;
(d) 222 kg;
(e) 160.1 k

51 .

(a) ix.threescore g; (b) 19.2 thou; (c) 28.viii g

53 .

zirconium: 2.038 $\times$ 10²³ atoms; 30.87 g; silicon: ii.038 $\times$ x²³ atoms; nine.504 one thousand; oxygen: viii.151 $\times$ 10²³ atoms; 21.66 m

55 .

AlPO₄: 1.000 mol or 26.98 g Al
Al_twoCl₆: 1.994 mol or 53.74 k Al
Al₂S₃: 3.00 mol or 80.94 1000 Al
The Al₂S₃ sample thus contains the greatest mass of Al.

57 .

3.113 $\times$ 10²⁵ C atoms

59 .

0.865 servings, or about 1 serving.

61 .

xx.0 k H₂O represents the to the lowest degree number of molecules since it has the least number of moles.

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Source: https://openstax.org/books/chemistry-atoms-first-2e/pages/chapter-2

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