Question 1

A particle is projected between two electrically charged plates. A beta ray is shown in comparison. Is the particle an electron?

Accepted Answer

Yes, the particle is an electron.

Question 2

Which statement correctly describes the atomic number and mass number of an atom?

Accepted Answer

Atomic number is equivalent to the number of protons while the mass number is equivalent to the sum of the number of protons and number of neutrons.

Question 3

Determine if the following statement is true: The nucleus is made up mostly of neutrons which make up most of the mass and volume of an atom.

Accepted Answer

False

Question 4

Identify the symbol, number of protons, and number of neutrons for the unknown isotope $$^{190}_{78}X.$$

Accepted Answer

#protons = 78, #neutrons = 112, Pt

Question 5

Which of the following isotope symbols is incorrect?
(i) $$^{40}_{19}P (ii$$) $$^{120}_{50}Sn ($$iii) $$^{29}_{63}Cu (iv$$) $$^{109}_{47}Au (v$$) $$^{58}_{26}Fe$$

Accepted Answer

(i), (iii), and (v)

Question 6

Given the following table of protons (p) and neutrons (n) for four isotopes, what are their correct isotope symbols?
(I) p=37, n=47
(II) p=37, n=48
(III) p=38, n=49
(IV) p=38, n=50

Accepted Answer

(i) $$^{84}_{37}Rb (ii$$) $$^{85}_{37}Rb ($$iii) $$^{87}_{38}Sr (iv$$) $$^{88}_{38}Sr$$

Question 7

Which characteristic do the neutral atoms of all isotopes of the same element share?

Accepted Answer

They have the same number of electrons.

Question 8

Given the following ions, provide the missing values for the number of electrons and protons:
Ga$$^{3+}$$, Ba$$^{2+}$$, F$$^{-}$$, Po$$^{2+}$$

Accepted Answer

Ga$$^{3+}$$: 28 protons, 31 electrons; Ba$$^{2+}$$: 56 protons, 54 electrons; F$$^{-}$$: 9 protons, 10 electrons; Po$$^{2+}$$: 84 protons, 86 electrons

Question 9

The subatomic particles in ions are different in the number of:

Accepted Answer

electrons

Question 10

Which set contains species with the same number of electrons? What is this relationship called?

Accepted Answer

Rb$$^{+}$$, Kr, Sr$$^{2+}$$; they are isoelectronic.

Question 11

Calculate the atomic weight of sulfur given the following natural isotopes:
$$^{32}S$$: 94.99%, 31.972 amu
$$^{33}S$$: 0.75%, 32.971 amu
$$^{34}S$$: 4.25%, 33.968 amu
$$^{36}S$$: 0.01%, 35.967 amu

Accepted Answer

32.065 amu

Question 12

Calculate the relative abundances of the isotopes of boron if Boron-10 has a mass of 10.0129 amu and Boron-11 has a mass of 11.0093 amu. The atomic mass of boron is 10.81 amu.

Accepted Answer

Boron-10 = 19.9%; Boron-11 = 80.1%

Question 13

A mass spectrum of an element displays four peaks with varying intensities indicative of four isotopes. Given the following information, determine the mass of the element and its identity:
Isotope 1: Mass (amu) 83.91343; Abundance (%) 0.5600
Isotope 2: Mass (amu) 85.90926; Abundance (%) 9.860
Isotope 3: Mass (amu) 86.90888; Abundance (%) 7.000
Isotope 4: Mass (amu) 87.90561; Abundance (%) 82.58

Accepted Answer

85.47 amu → Rubidium (Rb)

Question 14

Which of the following best describes a semimetal?

Accepted Answer

Semimetals have characteristics of both non-metals and metals and they act as borders with all the metals lying to their left and all of the non-metals on their right.

Question 15

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 16

A neutral atom of $$^{35}_{17}Cl$$ gains one electron. What is the resulting ion and its electron count?

Accepted Answer

Cl$$^{-}$$ with 18 electrons

Question 17

Which of the following best explains why the atomic mass of an element is not a whole number?

Accepted Answer

Because atomic mass is the weighted average of all naturally occurring isotopes.

Question 18

Which of the following ions is isoelectronic with Ne?

Accepted Answer

F$$^{-}$$

Question 19

A sample contains 60% $$^{63}Cu ($$mass = 62.9296 amu) and 40% $$^{65}Cu ($$mass = 64.9278 amu). What is the atomic mass of copper in this sample?

Accepted Answer

$$63.7293$$ amu

Atomic Structure, Isotopes, Ions, and Semimetals: General Chemistry Study Notes

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