Question 1

An atom of magnesium has 12 protons, 12 neutrons, and 10 electrons. What is the correct symbol for this ion?

Accepted Answer

$$\mathrm{^{24}_{12}Mg$$^{2+}$$}$$

Question 2

A neutral atom of chlorine has 17 protons and 18 neutrons. How many electrons does the chloride ion ($$\mathrm{Cl^-}) $$have?

Accepted Answer

18

Question 3

Which of the following correctly describes the relationship between the number of protons, electrons, and the charge of an ion?

Accepted Answer

Charge = Number of electrons $$-$$ Number of protons

Question 4

A sample of element X consists of 60% $$\mathrm{^{63}X} ($$mass = 63.0 u) and 40% $$\mathrm{^{65}X} ($$mass = 65.0 u). What is the average atomic mass of X?

Accepted Answer

$$64.2\ \mathrm{u}$$

Question 5

Which isotope symbol represents an atom with 20 protons, 22 neutrons, and 18 electrons?

Accepted Answer

$$\mathrm{^{42}_{20}Ca$$^{2+}$$}$$

Question 6

A certain ion has 26 protons, 30 neutrons, and 24 electrons. What is the charge and isotope symbol for this ion?

Accepted Answer

$$\mathrm{^{56}_{26}Fe$$^{2+}$$}$$

Question 7

Which of the following statements is true for an anion?

Accepted Answer

It has more electrons than protons.

Question 8

A hospital uses a radioactive isotope of iodine, $$\mathrm{^{131}I}$$, for thyroid imaging. If $$\mathrm{^{131}I}$$ has 53 protons, how many neutrons does it have?

Accepted Answer

78

Question 9

Which of the following best describes isotopes?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 10

A sample of boron contains 19.9% $$\mathrm{^{10}B} ($$mass = 10.0 u) and 80.1% $$\mathrm{^{11}B} ($$mass = 11.0 u). Calculate the atomic mass of boron.

Accepted Answer

$$10.8\ \mathrm{u}$$

Question 11

A neutral atom of potassium has 19 protons. What is the charge of a potassium ion with 18 electrons?

Accepted Answer

$$+1$$

Question 12

Which of the following ions has the same number of electrons as a neutral atom of neon ($$\mathrm{Ne}$$, atomic number 10)?

Accepted Answer

$$\mathrm{F^-}$$

Question 13

A certain isotope is represented as $$\mathrm{^{37}_{17}Cl^-}. $$How many protons, neutrons, and electrons does it have?

Accepted Answer

17 protons, 20 neutrons, 18 electrons

Question 14

Which calculation would you use to determine the number of neutrons in an atom?

Accepted Answer

Number of neutrons = Mass number $$-$$ Atomic number

Question 15

A sample of copper contains 69.2% $$\mathrm{^{63}Cu} ($$mass = 62.93 u) and 30.8% $$\mathrm{^{65}Cu} ($$mass = 64.93 u). What is the atomic mass of copper?

Accepted Answer

$$63.55\ \mathrm{u}$$

Question 16

A calcium ion is found to have 20 protons, 20 neutrons, and 18 electrons. What is its charge?

Accepted Answer

$$+2$$

Question 17

Which of the following best explains why isotopes of the same element have nearly identical chemical properties?

Accepted Answer

They have the same number of electrons and protons.

Question 18

A patient receives a dose of $$\mathrm{^{99m}Tc}$$ for a medical scan. If $$\mathrm{^{99m}Tc}$$ has 43 protons and 56 neutrons, what is its mass number?

Accepted Answer

99

Question 19

Which of the following ions is isoelectronic with argon ($$\mathrm{Ar}$$, atomic number 18)?

Accepted Answer

$$\mathrm{K^+}$$

Question 20

A student is given an unknown ion with 15 protons, 16 neutrons, and 18 electrons. What is the correct symbol for this ion?

Accepted Answer

$$\mathrm{^{31}_{15}P$$^{3-}$$}$$

Atoms, Ions, and Isotopes: Structure and Calculations

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