Question

isotope practice

1. here are three isotopes of an element: $_{6}^{12}c$ $_{6}^{13}c$ $_{6}^{14}c$

a. the element is: carbon
b. the number 6 refers to the atomic #
c. the numbers 12, 13, and 14 refer to the atomic mass
d. how many protons and neutrons are in the first isotope?
e. how many protons and neutrons are in the second isotope?
f. how many protons and neutrons are in the third isotope?

1. complete the following chart:

isotope name	atomic #	mass #	# of protons	# of neutrons	# of electrons
oxygen - 17	8	17	8	9	8
uranium - 235	92	235	92	143	92
uranium - 238	92	238	92	146	92
boron - 10	5	10	5	5	5
boron - 11	5	11	5	6	5

directions: for the following problems, show your work! be thorough.

1. naturally occurring europium (eu) consists of two isotopes was a mass of 151 and 153. europium - 151 has an abundance of 48.03% and europium - 153 has an abundance of 51.97%. what is the atomic mass of europium?
2. strontium consists of four isotopes with masses of 84 (abundance 0.50%), 86 (abundance of 9.9%), 87 (abundance of 7.0%), and 88 (abundance of 82.6%). calculate the atomic mass of strontium.
3. titanium has five common isotopes: $^{46}ti$(8.0%), $^{47}ti$(7.8%), $^{48}ti$(73.4%), $^{49}ti$(5.5%), $^{50}ti$(5.3%). what is the average atomic mass of titanium?

Explanation:

Step1: Recall atomic - related concepts

The atomic number is equal to the number of protons. The mass number is the sum of protons and neutrons. For a neutral atom, the number of electrons is equal to the number of protons.

Step2: Calculate for Carbon isotopes

For $^{12}C$: Atomic number = 6 (protons), mass number = 12. Neutrons = mass number - protons = 12 - 6 = 6.
For $^{13}C$: Protons = 6, mass number = 13. Neutrons = 13 - 6 = 7.
For $^{14}C$: Protons = 6, mass number = 14. Neutrons = 14 - 6 = 8.

Step3: Calculate for other isotopes in the chart

For Potassium - 37: Atomic number = 19, mass number = 37. Protons = 19, neutrons = 37 - 19 = 18, electrons = 19.
For Oxygen - 17: Atomic number = 8, mass number = 17. Protons = 8, neutrons = 17 - 8 = 9, electrons = 8.
For Uranium - 235: Atomic number = 92, mass number = 235. Protons = 92, neutrons = 235 - 92 = 143, electrons = 92.
For Uranium - 238: Atomic number = 92, mass number = 238. Protons = 92, neutrons = 238 - 92 = 146, electrons = 92.
For Boron - 10: Atomic number = 5, mass number = 10. Protons = 5, neutrons = 10 - 5 = 5, electrons = 5.
For Boron - 11: Atomic number = 5, mass number = 11. Protons = 5, neutrons = 11 - 5 = 6, electrons = 5.

Step4: Calculate atomic mass of Europium

Atomic mass of Europium = (0.4803×151)+(0.5197×153)
= 72.5253+79.5141
= 152.0394 ≈ 152 amu

Step5: Calculate atomic mass of Strontium

Atomic mass of Strontium=(0.005×84)+(0.099×86)+(0.07×87)+(0.826×88)
= 0.42 + 8.514+6.09+72.688
= 87.712 ≈ 88 amu

Step6: Calculate atomic mass of Titanium

Atomic mass of Titanium=(0.08×46)+(0.078×47)+(0.734×48)+(0.055×49)+(0.053×50)
= 3.68+3.666+35.232+2.695+2.65
= 47.923 ≈ 47.8 amu

Answer:

1.

• a. Carbon
• b. Atomic number
• c. Atomic mass
• d. Protons: 6, Neutrons: 6
• e. Protons: 6, Neutrons: 7
• f. Protons: 6, Neutrons: 8

1. See above - calculated values for the chart.
2. 152 amu
3. 88 amu
4. 47.8 amu