Question 1

Which experiment provided evidence for the existence of a small, dense, positively charged nucleus at the center of the atom?

Accepted Answer

Rutherford's gold foil experiment

Question 2

Which of the following statements about isotopes is CORRECT?

Accepted Answer

Isotopes of an element have different numbers of neutrons.

Question 3

A neutral atom of chlorine-37 has an atomic number of 17. How many neutrons does it contain?

Accepted Answer

$$37 - 17 = 20$$ neutrons

Question 4

Which of the following best explains why atoms are electrically neutral?

Accepted Answer

They have equal numbers of protons and electrons.

Question 5

Which electron configuration represents a potassium ion, $$K^+$$?

Accepted Answer

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

Question 6

Which of the following elements has the largest atomic radius?

Accepted Answer

Aluminum ($$Al)$$

Question 7

Which of the following atoms has the highest first ionization energy?

Accepted Answer

Phosphorus ($$P)$$

Question 8

Which of the following electron configurations represents a ground-state nitrogen atom?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^3$$

Question 9

Which principle states that electrons fill orbitals of lowest energy first?

Accepted Answer

Aufbau Principle

Question 10

Which of the following best describes the difference between the 1s and 2s orbitals?

Accepted Answer

The 2s orbital is larger and higher in energy than the 1s orbital.

Question 11

Which of the following elements is most metallic?

Accepted Answer

Tin ($$Sn)$$

Question 12

Which of the following statements about the periodic table is TRUE?

Accepted Answer

Elements in the same group have the same number of valence electrons.

Question 13

A sample of neon contains 90.48% $$^{20}Ne$$, 9.25% $$^{22}Ne$$, and 0.27% $$^{21}Ne. $$Which isotope is most abundant?

Accepted Answer

$$^{20}Ne$$

Question 14

Which of the following best explains why alkali metals are highly reactive?

Accepted Answer

They have one valence electron and tend to lose it to achieve a noble gas configuration.

Question 15

Which of the following is the correct noble gas electron configuration for arsenic ($$As$$, $$Z=33$$)?

Accepted Answer

$$[Ar] 4s^2$ 3d$$^{10}$$ 4p^3$

Question 16

Which of the following best describes the Pauli Exclusion Principle?

Accepted Answer

No two electrons in the same atom can have the same set of four quantum numbers.

Question 17

Which of the following ions has the same electron configuration as neon ($$Ne$$)?

Accepted Answer

$$F^-$$

Question 18

Which of the following best explains the trend in atomic size as you move down a group in the periodic table?

Accepted Answer

Atomic size increases due to additional energy levels being added.

Question 19

Which of the following is the correct electron configuration for a manganese ($$Mn) $$atom ($$Z=25$$)?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^5$$

CH.3:Atomic Structure and Electron Configuration: Study Guide for Introductory Chemistry

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