$$2\text{Li} + 2\text{H}_2\text{O} \rightarrow 2\text{LiOH} + \text{H}_2$$

Question 1

Which element is shown in the first image, and what property makes it highly reactive with water?

Accepted Answer

Lithium; its single valence electron in the 2s orbital

Question 2

The second image shows a reaction occurring in water. Which equation best represents the reaction of lithium with water?

Accepted Answer

$$2	ext{Li} + 2	ext{H}_2	ext{O} ightarrow 2	ext{LiOH} + 	ext{H}_2$$

Question 3

The third image shows a lithium battery. Which property of lithium makes it especially useful in batteries?

Accepted Answer

Its ability to easily lose its single valence electron

Question 4

Which quantum mechanical principle explains why electrons fill the 1s orbital before the 2s orbital?

Accepted Answer

Aufbau principle

Question 5

Which of the following is the correct full electron configuration for a sulfur atom?

Accepted Answer

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

Question 6

Which rule states that electrons will fill degenerate orbitals singly before pairing up?

Accepted Answer

Hund's rule

Question 7

What is the shorthand (noble gas) electron configuration for chlorine?

Accepted Answer

$$[Ne]3s^2$ 3p^5$

Question 8

Which of the following best explains why the 4s orbital fills before the 3d orbital?

Accepted Answer

The 4s orbital has lower energy due to penetration effect

Question 9

Which element has the electron configuration $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^8$$?

Accepted Answer

Nickel (Ni)

Question 10

Which of the following ions has the electron configuration $$1s^2$$ $$2s^2$$ $$2p^6$$?

Accepted Answer

$$	ext{Mg}^{2+}$$

Question 11

Which of the following best describes the cause of ferromagnetism in iron, cobalt, and nickel?

Accepted Answer

Presence of several unpaired electrons and domain alignment

Question 12

Which of the following is the correct order of orbital energies in a multi-electronic atom for a given principal quantum number $$n$$?

Accepted Answer

$$s \u003c p \u003c d \u003c f$$

Question 13

Which element is expected to have the electron configuration $$[Ar]4s^2$ 3d^5$?

Accepted Answer

Manganese (Mn)

Question 14

Which of the following is an exception to the expected order of orbital filling, and what is its observed configuration?

Accepted Answer

Copper (Cu); $$[Ar]4s^1$ 3d$$^{10}$$

Question 15

Which quantum number determines the number of orbitals in a subshell?

Accepted Answer

Magnetic quantum number ($$m_l)$$

Question 16

What is the electron configuration for the calcium ion $$	ext{Ca}^{2+}$$?

Accepted Answer

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

Question 17

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

Accepted Answer

They have the same valence electron configuration

Question 18

Which orbital is being filled for the halogen with electrons in the 6p atomic orbitals?

Accepted Answer

6p

Question 19

Which of the following best describes the electron correlation problem in multi-electronic atoms?

Accepted Answer

The inability to calculate the exact repulsions between electrons

Lesson 3.5: Atomic Structure and the Periodic Table: Electron Configurations and Periodic Trends

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