Question 1

According to the Bohr model, what is the relationship between the radius of an electron's orbit and its energy level?

Accepted Answer

Electrons in orbits of larger radii have higher energy.

Question 2

Which of the following best describes the octet rule?

Accepted Answer

Atoms prefer to have 8 electrons in their outer shell, except hydrogen and helium which prefer 2.

Question 3

What is the electron configuration for sodium (Na), which has an atomic number of 11?

Accepted Answer

$$2, 8, 1$$

Question 4

Which statement about valence electrons is correct?

Accepted Answer

Valence electrons require the least amount of energy to remove from the atom.

Question 5

How many electrons can the third electron shell hold for the first 20 elements?

Accepted Answer

$$8$$

Question 6

Which of the following ions has a full outer shell according to the octet rule?

Accepted Answer

$$\mathrm{Na^+}$$

Question 7

What is the correct Lewis dot diagram for a chloride ion ($$\mathrm{Cl^-}$$)?

Accepted Answer

Eight dots around Cl inside brackets with a negative sign: $$[\cdot\cdot\cdot\cdot\cdot\cdot\cdot\cdot]^{-}$$

Question 8

Which element has the electron configuration $$2, 8, 8, 1$$?

Accepted Answer

Potassium ($$K)$$

Question 9

If an atom loses two electrons, what type of ion does it form?

Accepted Answer

A cation with a $$2^+$$ charge

Question 10

Which of the following best explains why electrons fill the lowest energy shells first?

Accepted Answer

Electrons are attracted to the nucleus and occupy the lowest available energy states to minimize the atom's energy.

Question 11

What is the electron configuration for a $$\mathrm{O$$^{2-}$$}$$ ion?

Accepted Answer

$$2, 8$$

Question 12

Which statement about Lewis dot diagrams is correct?

Accepted Answer

Lewis dot diagrams show only the valence electrons of atoms or ions.

Question 13

Which of the following elements has three valence electrons?

Accepted Answer

Aluminum ($$Al)$$

Question 14

A neutral atom of magnesium ($$Mg) $$has an atomic number of 12. What is its electron configuration?

Accepted Answer

$$2, 8, 2$$

Question 15

Which of the following is a limitation of Rutherford's model that led to Bohr's model?

Accepted Answer

Rutherford's model could not explain the stability of electrons in the atom.

Question 16

Which of the following best describes a cation?

Accepted Answer

An atom that has lost electrons and has a positive charge.

Question 17

What is the electron configuration for a neutral atom of chlorine ($$Cl$$)?

Accepted Answer

$$2, 8, 7$$

Question 18

Which of the following statements about Bohr diagrams is correct?

Accepted Answer

Bohr diagrams show the arrangement of electrons in each shell around the nucleus.

Question 19

If an atom has the electron configuration $$2, 8, 8$$, what is its atomic number?

Accepted Answer

$$18$$

Question 20

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full outer shell of electrons, satisfying the octet rule.

Atomic Structure and Electron Configuration: Foundations for Organic Chemistry

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