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SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
Complete the following Textbook questions.
P.10 # 3, 4;
3.
(a) Answers may vary. Sample answer: Carbon dioxide is a greenhouse gas, and increased atmospheric levels
are leading to increased average global temperatures and climate change.
(b) Answers may vary. Sample answer: Alternative energy technologies, such as solar cells, are being
developed to reduce the use of fossil fuels and CO2 emissions. Some of the many other ways to reduce CO2
emissions are to use energy-efficient vehicles and appliances, travel less, and eat less meat.
4. Empirical knowledge is knowledge that comes from investigation and observation. Theoretical knowledge is
knowledge based on ideas created to explain scientific observations.
P. 16 # 10
10. There are 119 protons, 119 electrons, and 183 neutrons in each atom of this element.
Complete the following Textbook questions.
1. P.27# 1;
1. (a) Given: atomic mass and abundance of the three isotopes of neon
Required: atomic mass of neon
Analysis:
AAM = % abundance of isotope 1 (mass of isotope 1) + % abundance of isotope 2 (mass of isotope 2) + %
abundance of isotope 3 (mass of isotope 3)
Solution:
Step 1. Substitute the known values into the equation.
AAM = 90.5 % (20 u) + 0.3 % (21 u) + 9.2 % (22 u)
Step 2. Solve the equation.
AAM = 20.2 u
Statement: The relative atomic mass of neon is 20.2 u.
(b) Given: atomic mass and abundance of the five isotopes of titanium
Required: atomic mass of titanium
Analysis:
AAM = % abundance of isotope 1 (mass of isotope 1) + % abundance of isotope 2 (mass of isotope 2) + %
abundance of isotope 3 (mass of isotope 3) + % abundance of isotope 4 (mass of isotope 4) + % abundance
of isotope 5 (mass of isotope 5)
Solution:
Step 1. Substitute the known values into the equation.
AAM = 7.9 % (46 u) + 7.3 % (47 u) + 73.9 % (48 u) + 5.5 % (49) + 5.4 % (50)
Step 2. Solve the equation.
AAM = 47.9 u
Statement: The relative atomic mass of titanium is 48 u.
W1 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
P.29 # 2, 8, 10
2. It is not possible for a single atom of chlorine to have a mass number of exactly 35.45. The mass number is
the sum of the protons and neutrons in the nucleus of an atom. Since you cannot have fractions of protons
and neutrons, both the number of protons and the number of neutrons must be whole numbers, so the sum
will be a whole number.
8. Isotopes are atoms that have the same number of protons but different numbers of neutrons. A
radioisotope is an isotope with an unstable nucleus that spontaneously decays to produce two or more smaller
nuclei.
10. Answers may vary. Sample answer: Three careers in which people handle radioisotopes are nuclear
chemist, radiologist, or radioisotope lab technician. To reduce their exposure to radiation, these workers use
shielding between themselves and the radioactive source, and they keep the time they are exposed to the
radiation to a minimum. They wear protective clothing and never take that clothing out of the lab. They keep
radioactive material away from other materials and do not eat or drink in areas where radioactive materials
are used. They dispose of radioactive waste carefully.
W2 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
Radioactive Decay and Half-Life Problems
Write out the Half Life Equation:
For each problem below, provide a full solution and express your answer to the correct number of significant
digits.
1. The half-life of iodine-131 is 8.1 days. How much of a 450.84 g sample of iodione-131 will remain after
3.0 weeks? [75 g]
Af = 450.84g (1/2)21days/8.1
Af = 450.84g (1/2)2.593
Af = 450.84g (0.1657)
Af = 74.7
∴ 75g of iodine-131 will remain after 3 weeks.
2. The half-life of radon-222 is 3.82 days. After 15 days, only 5.0 g of a sample of radon-222 is left. What
was the original mass of the sample? [76 g]
Af = 5.0g
5.0g = Ai (1/2)15days/3.82
5.0g = Ai (1/2)3.926701571
5.0g = Ai (0.06575746208)
5.0g/0.06575746208 = Ai
Ai = 76g
∴ The original mass of the sample was 76g.
3. The half-life life of radon-222 is 3.82 days. If the sample of gas originally contains 4.38 g, how much
will remain in the sample after 15.2 days? [0.278 g]
Af = 4.38g (1/2)15.2days/3.82
Af = 4.38g (0.06341387766)
Af = 0.2777527842
Af = 2.78
∴ 0.278g of the sample will remain after 15.2 days.
W3 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
4. A sample of Francium-212 will decay to one-sixteenth its original amount after 80 minutes. What is the
half-life of Francium-212? [20 min]
1/16 = 1(1/2)80min/t1/2
1/16 = (1/2) 80min/t1/2
(1/2)4 = (1/2) 80min/t1/2
4 = 80/t1/2
t1/2 = 20
∴ The half-life of francium-212 is 20 minutes.
5. A sample of strontium-90 is found to have decayed to one-eigth of its original mass after 87.3 years.
What is the half-life of strontium-90? [29.1 a]
1/8 = 1(1/2)87.3a/t1/2
1/8 = (1/2)87.3a/t1/2
(1/2)3 = (1/2) 87.3a/t1/2
3 = 87.3/t1/2
t1/2 = 29.1
∴ The half-life of strontium-90 is 29.1a.
6. The half-life of iodine-131 is 8.1 days. How long will it take for 120.70 g of iodine-131 to decay to
30.18 g?
[16.2 d]
30.18g = 120.70g (1/2)t/8.1
30.18g/120.70g = (1/2)t/8.1
0.25 = (1/2)t/8.1
(1/2)2 = (1/2)t/8.1
2 = t/8.1
t = 16.2
∴ It takes the iodine-131 16.2 days to decay.
W4 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
1. Distinguish between an isotope and a radioisotope.
An ISOTOPE is an atom of an element with a different number of neutrons than the original element.
RADIOISOTOPES, however, are unstable by nature due to several things going on in the nucleus. They
are isotopes by definition, but they have unusually high levels of unstable energy in the nucleus and
thus emit this energy in the form of radiation.
They may undergo various types of radioactive decay (alpha, beta or gamma) ,all in an effort to expel
energy and become more stable.
By definition, "radioisotopes" are inherently unstable, whereas "isotopes" may be either stable or
unstable... but usually refer to stable isotopes.
Complete the following Textbook questions.
2.
P. 50 # 49, 50; P. 51 # 65
49. Gamma rays have a greater ability to penetrate solid matter than either of the other rays. Also, gamma
rays are high-energy radiation, so they are likely to be most deadly to the cancer cells.
50. The atomic number of the daughter material will be 2 less than the atomic number of the parent material.
Also, the mass number will be 4 less than that of the parent material. This is because an alpha particle
consists of 2 protons and 2 neutrons, which come from the decay of the parent material.
65.
(a) A beta particle forms during the radioactive decay of C-14 into N-14.
(b) The mass of the atom did not change (both atoms have a mass of 14), but the identity of the
element did change. Only the emission of a beta particle fits this evidence.
W5 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
Periodic Table Worksheet
1. Where are the most active metals located? ______ on the lower left side of the periodic table.___.
2. Where are the most active non-metals located? ___on the upper right side of the periodic table.
3. As you go from left to right across a period, the atomic radius (increases/decreases). Why?
Increased positive nuclear charge, ENC increases, F of A increases.
4. As you travel down a group, the atomic radius (increases/decreases). Why? # of E.L. increases ,
F of A decreases.
5. A negative ion is (larger/smaller) than its parent atom.
6. A positive ion is (larger/smaller) than its parent atom.
7. As you go from left to right across a period, the first ionization energy generally
(increases/decreases). Why? Increased positive nuclear charge, ENC increases, F of A increases.
8. As you travel down a group, the first ionization energy generally (increases/decreases). Why? # of E.L.
increases , F of A decreases.
9. Elements of Group 1 are called _________ alkali metals ____________________.
10. Elements of Group 2 are called _____________ alkaline earth metals____________.
11. Elements of Groups 3-12 are called ____________transition metals ________________________.
12. As you go from left to right across the periodic table, the elements go from (metals/non-metals) to
(metals/non-metals).
13. Elements of Groups 17 are called ____________________ halogens _________________.
14. The most active element in Group 17 is ________________ Fluorine (F)___________________.
15. Elements of Groups 18 are called _________________________ noble gases ___________________.
16. Elements within a group have a similar number of __ valence electrons..
17. Elements across a period have the same number of ___ principal energy levels ___.
18. As you go down a group, the elements generally become (more/less) metallic.
19. The majority of elements in the periodic table are (metals/non-metals).
20. Elements in the periodic table are arranged according to their _____ atomic numbers _______.
21. An element with both metallic and non-metallic properties is called a ______ metalloid.
W6 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
Complete the following Textbook questions.
23. P. 33 # 3, 5(a), 7(a), (b);
3.
An electron arrangement is how many electrons are around the nucleus and where there are. Electron
arrangement definitely does affect the chemical properties of an atom. For example, if we take a look at Group
18, the noble gases, they all have a full valance shell. It doesn’t matter whether you move up or down the
group; they will all have a full valance shell, making the atom unreactive.
All the noble gases have filled valence shells. This results in noble gases being unreactive and
the fact that they do not readily combine with other elements to form compounds.
7.
(a) Cs is more reactive than Ba.
(b) F is more reactive than C.
P. 51 #71
71. Noble gases were likely discovered so late because they do not readily react with other elements, and
some of them do not react at all. Thus, they were not present in compounds. In addition, they were all gases
and could not be seen. Noble gases are unreactive gases because their valance shell is full. Most elements
were discovered through their reactivity with other metals. It would have been very difficult for scientists to
discover an element that seemed to have little or no chemical properties based on their reactivity.
PROPERTIES OF ATOMS
1.
Which chemical family has the lowest I.E. values?
Group 1 2.
Which chemical family has the highest I.E. values?
Group 17 3.
Does the ionization energy increase/decrease as you go left to right across the Periodic Table?
4.
Does the electronegativity increase/decrease as you down each family on the Periodic Table?
5.
Does the Atomic Radius increase/decrease as you down each family on the Periodic Table?
6.
Explain the trend in atomic radius for a particular group and a particular row of the periodic table.
PERIOD - Increased positive nuclear charge, ENC increases, F of A increases.
GROUP - # of E.L. increases, F of A decreases.
W7 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding 7.
Name: _________________________
Rubidium has a lower first IE than does sodium. Explain why.
Due to the increased number of energy levels, atomic radius increases. Therefore, according to
Coulomb's Law, force of attraction between the nucleus and the outer electrons should decrease
as one goes down the group. Therefore it will become less difficult to remove an electron.
8.
Explain which species in each of the following pairs will have the greatest EN.
a. potassium or calcium
Explanation:
(i) effective nuclear charge (enc)- Increases
(ii) the atomic radius (distance)- Decreases
(iii) Force of attraction - Increases
9.
b. sulfur or selenium
Explanation:
(i) number of energy levels - Decreases
(ii) the atomic radius (distance)- Decreases
(iii) Force of attraction - Increases
Explain which element of the following pairs, will have the smaller radius:
a. sodium or chlorine
Explanation:
(i) effective nuclear charge (enc)- Increases
(ii) the atomic radius (distance)- Decreases
(iii) Force of attraction - Increases
10.
b. calcium or chlorine
Explanation:
(i) number of energy levels - Decreases
(ii) the atomic radius (distance)- Decreases
(iii) Force of attraction - Increases
Consider the following table of Ionization Energies (measured in kJ/mol)
ELEMENT
1st
2nd
3rd
4th
5th
6th
Na
496
4562
6912
9544
13353
16610
Mg
738
1451
7733
10540
13630
17995
Al
578
1817
2745
11577
14831
18378
a.
Explain why the 1st IE generally increases as one goes down the group of elements listed above.
Due to the increased number of energy levels, atomic radius increases. Therefore, according to
Coulomb's Law, F of A between the nucleus and the outer electrons should decrease as one goes
down the group. Therefore it will become less difficult to remove an electron.
b.
Explain why:
(i) for Na, there is a large increase in IE in going from 1st to 2nd.
1 valence electron - once removed the noble gas configuration is achieved, a lot more energy is
required to remove the next electron from a cation.
(ii) for Mg, there is a large increase in IE in going from 2nd to 3rd.
2 valence electrons - once removed the noble gas configuration is achieved, a lot more energy is
required to remove the next electron from a cation.
W8 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
(iii) for Al, there is a large increase in IE in going from 3rd to 4th.
3 valence electrons - once removed the noble gas configuration is achieved, a lot more energy is
required to remove the next electron from a cation.
c.
Where would the large increase in IE occur for S, Cl, Ar? Explain your answer
S 6th to 7th
Cl 7th to 8th
Ar 8th to 9th
There is a noticeable jump in increase of I.E. since the noble gas configuration has been reached.
11.
The atoms of 5 different elements, "A", "B", "C", "D", "E" have the following number of electron
in each consecutive energy level:
"A"
"D"
a.
2 8 1
2 8 2
"B"
"E"
2 8
2 7
"C"
2 5
Explain which element would have the lowest first IE.
"A" 2 8 1
(i) effective nuclear charge (ENC)- Smallest
(ii) number of energy levels (distance)- Largest
(iii) Force of attraction - Weakest
b.
Explain which element would have the highest first IE.
E" 2 7
(i) effective nuclear charge (ENC)- Greatest
(ii) number of energy levels (distance)- Smallest
(iii) Force of attraction – F of A- Strongest
c.
Explain which element would have the lowest second IE.
"D" 2 8 2 becomes "D+" 2 8 1
(i) effective nuclear charge (ENC)- Smallest
ii) number of energy levels (distance)- Largest
(iii) Force of attraction – F of A- - Weakest
12.
Use their placement on the periodic table to arrange the following elements based on their size (atomic
radii) from largest to smallest.
a. Ca, Ge, Br, K, Kr
b. Sr, Mg, Be, Ba, Ra
c. F, Cl, Fr, Cs
13.
Use their placement on the periodic table to arrange the following elements from highest ionization
energy to lowest ionization energy.
a. Ca, Ge, Br, K, Kr
b. Sr, Mg, Be, Ba, Ra
c. F, Cl, Fr, Cs
W9 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
14.
Use their placement on the periodic table to determine which of the following is smaller.
a. Ca atom or Ca ion
b. Cl atom or Cl ion
c. N ion or O ion
d. Mg ion or Sr ion
15.
Which of the following has the most shielding?
a. Br or F
b. Al or Cl or neither
c. Ca or Ra
16.
When sodium becomes an ion _______electrons are _________(lost/gained).
17.
When aluminum ionizes, _____ electrons are ______. Nitrogen ionizes and _____ electrons are ____.
18.
An ion that has a charge of +2 with 20 protons is the ____ ion. It has ____ electrons and __ neutrons.
19.
The ion that has a -3 charge with 19 electrons is _______
20.
The ion that has a +3 charge with 26 protons is ________.
_____________________________________________________________________________________
12.
13.
14.
15.
16.
17.
18.
19.
20.
a. K,Ca,Ge,Br,Kr b. Ra,Ba,Sr,Mg,Be
a. Kr,Br,Ge,Ca,K b. Be,Mg,Sr,Ba,Ra
a. Ca ion
b. Cl atom
a. Br
b. neither
c. Ra
1, lost
3, lost, 3, gained
Ca2+,18,20
S3Fe3+
c. Fr,Cs,Cl,F
c. F,Cl,Cs,Fr
c. O ion
d. Mg ion
Complete the following Textbook questions.
22. P. 41 # 6, 7, 11;
6. (a) The sulfide ion, S2–, is larger than the sulfur atom, S, because anions are always bigger than their
original neutral ions.
(b) The calcium ion, Ca2+, is smaller than the calcium atom, Ca, because cations are always smaller than their
original neutral atom.
(c) The fluoride ion, F–, is larger than the lithium ion, Li+.
Sample explanation: From Figure 3 on page 37, it looks like the radius is about 100 pm larger when the atom
gains an electron and about 100 pm smaller when an electron is removed. The atomic radius of Li is 167 pm,
so the ionic radius of Li+ will be about 67 pm. The atomic radius of F is 42 pm, so the ionic radius of F– will be
about 142 pm.
(d) The bromine ion, Br–, is larger than the chloride ion, Cl–. Students’ explanations may vary.
Sample explanation: The bromine atom, B, is larger than the chlorine atom, Cl, so when each of these two
atoms gains an electron, bromine will likely remain larger.
W10 SCH 3U-­‐ R. H. KING ACADEMY Matter and Bonding Name: _________________________
7. There should be no significant differences between the first ionization energies of two isotopes
of a given element, because neutrons are uncharged particles and the ionization energy is determined by the
attraction between protons and electrons.
11. Sample answers: Since Element 119 is an alkali metal, it will be soft, silver-coloured, and a solid at room
temperature. It should be extremely reactive with water and air. It may have properties similar to those of
francium or cesium.
P. 53 #87
87.
(a) This situation is analogous to removing a valence electron from an atom because energy must be exerted
to remove both the puck from the hands and the electron from the atom.
(b) The term applied to the amount of energy needed to remove a valence electron from an atom is ionization
energy.
Periodic Table Puzzle The code letters A to Z have been assigned to the elements which occupy the positions shown in this short form periodic table (note only the first 4 rows of groups 1,2 and 13-­‐18 have been included). Use the clues below to arrange the letters A to Z in their proper place on the Periodic Table. 1 F 2 13 14 15 16 17 18 X 2 S H D U M A V B 3 I T Z N Y Q O E 4 P L R G C K W J W11