Question 1

Which of the following statements best describes the difference between isotopes of the same element?

Accepted Answer

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

Question 2

A neutral atom of calcium-40 ($$^{40}_{20}\mathrm{Ca}) is $$used in a medical imaging procedure. How many protons, neutrons, and electrons does this atom have?

Accepted Answer

20 protons, 20 neutrons, 20 electrons

Question 3

Which of the following elements is a metalloid and would be expected to have properties intermediate between metals and nonmetals?

Accepted Answer

Silicon (Si)

Question 4

A sample of gallium contains 60.4% $$^{69}\mathrm{Ga} ($$mass = 68.9257 amu) and 39.6% $$^{71}\mathrm{Ga} ($$mass = 70.9248 amu). What is the atomic weight of gallium? (Round to one decimal place.)

Accepted Answer

$$69.7\ \mathrm{amu}$$

Question 5

Which group of the periodic table contains elements that are colorless, chemically unreactive gases at room temperature?

Accepted Answer

Group 8A (Noble gases)

Question 6

Which of the following electron configurations represents a neutral atom of magnesium ($$\mathrm{Mg}$$, atomic number 12)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$

Question 7

A hospital uses a radioactive isotope of iodine, $$^{131}\mathrm{I}$$, for thyroid imaging. What is the number of neutrons in this isotope?

Accepted Answer

$$131 - 53 = 78$$ neutrons

Question 8

Which of the following best explains why alkali metals (Group 1A) are never found in nature in their pure state?

Accepted Answer

They are highly reactive and readily combine with other elements.

Question 9

Which of the following is the correct electron-dot (Lewis) symbol for an atom of nitrogen (Group 5A)?

Accepted Answer

The symbol N with five dots: one on each side and one paired

Question 10

Which of the following statements about the quantum mechanical model of the atom is correct?

Accepted Answer

Electrons are restricted to certain energy values, called quantized energy levels.

Question 11

A patient receives a dose of a radioactive isotope with the symbol $$^{99}_{43}\mathrm{Tc}. $$Identify the element, and state the number of protons, neutrons, and electrons in a neutral atom of this isotope.

Accepted Answer

Element: Technetium; 43 protons, 56 neutrons, 43 electrons

Question 12

Which of the following elements has the electron configuration $$[\mathrm{Ne}]\ 3s^2$\ 3p^5$?

Accepted Answer

Chlorine (Cl)

Question 13

Which of the following best describes the trend in atomic radius as you move from left to right across a period in the periodic table?

Accepted Answer

Atomic radius decreases due to increasing nuclear charge.

Question 14

Which of the following is the correct general valence-shell electron configuration for elements in group 6A?

Accepted Answer

$$ns^2$$\ $$np^4$$

Question 15

A tin atom (Sn) has an atomic number of 50. How many valence electrons does it have, and what is its valence-shell configuration?

Accepted Answer

4 valence electrons; $$5s^2$$\ $$5p^2$$

Question 16

Which of the following statements about the arrangement of electrons in atoms is correct?

Accepted Answer

Each orbital can hold a maximum of two electrons with opposite spins.

Question 17

Which of the following elements is most likely to be a poor conductor of electricity and found as a colorful, corrosive gas at room temperature?

Accepted Answer

Chlorine (Cl)

Question 18

Which of the following best explains why elements in the same group of the periodic table have similar chemical properties?

Accepted Answer

They have similar valence electron configurations.

Question 19

A neutral atom has its first and second shells filled and four electrons in its third shell. What is the atomic number and identity of this element?

Accepted Answer

Atomic number 14; Silicon (Si)

Question 20

Which of the following is the correct order of filling for the first four subshells according to the Aufbau principle?

Accepted Answer

$$1s \rightarrow 2s \rightarrow 2p \rightarrow 3s$$

Atoms and the Periodic Table: Structured Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard