CTJan27 Online JMSS - Electron Configuration and Valance Electrons

1

According to the electron shell model, what is the designation used for the innermost principal energy level ($n=1$)?

K-shell J-shell M-shell P-shell

2

How is the energy of an electron generally related to its principal quantum number ($n$) in a neutral atom?

Energy decreases as $n$ increases (closer to the nucleus). Energy increases as $n$ increases (farther from the nucleus). Energy remains constant regardless of $n$. Energy is only dependent on the neutron count.

3

What is the maximum number of electrons that can be held in the second principal energy level, also known as the L-shell ($n=2$)?

$2$ electrons $8$ electrons $18$ electrons $32$ electrons

4

The general formula used to determine the theoretical maximum electron capacity ($N$) of any given shell with principal quantum number ($n$) is:

$N = n^2$ $N = 2n^2$ $N = 2n$ $N = n/2$

5

When an electron absorbs a specific, discrete amount of energy (a quantum), it typically undergoes a transition to:

A lower energy shell (closer to the nucleus). A higher energy shell (farther from the nucleus). The nucleus itself. A different atom entirely.

6

If an electron transitions spontaneously from the $n=3$ shell to the $n=1$ shell, what is the consequence?

Energy is absorbed to facilitate the move. The atomic mass increases. Energy is emitted, usually as a photon. The electron remains in the $n=3$ shell indefinitely.

7

Electrons located in the outermost occupied shell of an atom are specifically called:

Core electrons Valence electrons Inner electrons Neutral electrons

8

Calculate the maximum number of electrons that can theoretically occupy the M-shell ($n=3$).

$6$ $10$ $18$ $30$

9

What is the term for the most stable condition where all electrons in an atom occupy the lowest possible energy levels?

Excited state Ionized state Ground state Thermal state

10

Which statement correctly describes the relative energy of the K-shell ($n=1$) compared to the N-shell ($n=4$)?

The N-shell and K-shell have approximately equal energy. The K-shell has higher energy than the N-shell. The K-shell has the lowest energy of all principal shells ($n=1, 2, 3, 4$). Energy levels only depend on the number of protons.

11

An atom has $12$ electrons. What is the electron configuration for the first three shells ($n=1, n=2, n=3$) in the ground state?

$12, 0, 0$ $2, 10, 0$ $2, 8, 2$ $4, 4, 4$

12

Why are valence electrons crucial for understanding chemical interactions?

They primarily determine the mass of the atom. They determine the chemical reactivity and bonding patterns of the element. They solely stabilize the nucleus. They are the only electrons that carry a negative charge.

13

As the distance from the nucleus increases (i.e., moving from $n=3$ to $n=4$), how does the energy difference ($\Delta E$) between consecutive shells change?

The difference $\Delta E$ remains constant throughout all shells. The difference $\Delta E$ increases significantly. The difference $\Delta E$ decreases, meaning the shells get closer in energy. The difference $\Delta E$ becomes zero.

14

An electron is described as being in the 'excited state' if it occupies:

The lowest available energy level. Any energy level higher than its ground state configuration. A shell that is closer to the nucleus than the $n=1$ shell. A position precisely in the middle of two principal shells.

15

What is the maximum number of electrons that can theoretically occupy the N-shell ($n=4$)?

$8$ $16$ $32$ $64$

16

If an electron drops from the N-shell ($n=4$) to the L-shell ($n=2$), the total energy released will be:

Absorbed by the nucleus to form a neutron. Equal to the energy difference between $E_4$ and $E_2$. Twice the energy difference between $E_3$ and $E_2$. Zero, as energy is only involved when moving outward.

17

The term 'principal quantum number' ($n$) primarily indicates the electron's:

Direction of spin and angular momentum. Electrical charge and mass. Energy level and average distance from the nucleus. Exact position at any given moment.

18

The sequential naming convention K, L, M, N corresponds to which principal quantum numbers?

$n=1, 2, 3, 4$ $n=2, 4, 6, 8$ $n=0, 1, 2, 3$ $n=K, L, M, N$

19

An element has $15$ electrons. Assuming ground state configuration, how many electrons are found in its outermost principal shell?

$2$ (Configuration: $2, 8, 5$) $5$ (Configuration: $2, 8, 5$) $8$ (Configuration: $2, 8, 5$) $15$ (Configuration: $15$)

20

What fundamental concept of atomic structure explains why electrons occupy only specific, discrete energy levels?

The electrons have zero mass and are thus not affected by gravity. The Pauli Exclusion Principle dictates all orbital motion. The energy of electrons is quantized. Electrons always travel in straight lines unless acted upon by the nucleus.

21

What are valence electrons?

Electrons located closest to the nucleus Electrons involved in energy absorption Electrons in the outermost occupied energy shell Electrons shared only in metallic bonds

22

For an atom to achieve maximum chemical stability, its valence shell must typically follow which rule?

The Hund Rule The Pauli Exclusion Principle The Octet Rule The Duet Rule (unless Hydrogen or Helium)

23

How many valence electrons does a neutral atom of Sulfur ($S$) have, given its atomic number $Z=16$?

$2$ $6$ $8$ $16$

24

Which statement best describes the chemical reactivity of elements in Group $18$ (Noble Gases)?

They are highly reactive because they readily gain electrons They are highly reactive because they readily lose electrons They are generally non-reactive because they already possess a full valence shell They react easily with halogens but not with alkali metals

25

An atom of a certain element has the electron configuration $2, 8, 1$. To achieve stability, what is the most likely action for this atom?

Gain $7$ electrons Lose $1$ electron Gain $1$ electron Lose $8$ electrons

26

If an atom loses $2$ valence electrons, what type of ion is formed, and what is its charge?

Anion, $-2$ Cation, $+2$ Anion, $+2$ Cation, $-2$

27

The Duet Rule, which indicates chemical stability with $2$ valence electrons, primarily applies to which set of elements?

All transition metals Elements in Group $17$ Helium and Hydrogen Noble gases only

28

How many electrons must a neutral Nitrogen ($N$) atom ($Z=7$) gain to satisfy the Octet Rule?

$5$ $3$ $7$ $8$

29

What is the main characteristic shared by all elements within the same group (column) of the periodic table, concerning their outermost shell?

They have the same atomic mass They have the same number of filled inner electron shells They have the same number of valence electrons They have the same total number of electrons

30

When Sodium ($Na$) loses its sole valence electron, it achieves the stable electron configuration of which noble gas?

Neon ($Ne$) Argon ($Ar$) Helium ($He$) Krypton ($Kr$)

31

Which term describes the outermost occupied energy level of an atom?

Core shell Electron cloud Principal quantum number Valence shell

32

An element is highly reactive and tends to form ions with a $-1$ charge. How many valence electrons did the neutral atom most likely possess?

$1$ $2$ $7$ $8$

33

Why does chemical bonding occur between atoms?

To increase the overall mass of the resulting compound To fulfill the required number of protons in the nucleus To achieve a lower energy state by obtaining a stable electron configuration To force the outer shell electrons into a higher energy state

34

What is the resulting charge of the stable ion formed by Calcium ($Ca$), an element with $2$ valence electrons?

$Ca^{1-}$ $Ca^{2+}$ $Ca^{2-}$ $Ca^{1+}$

35

Consider two atoms: Atom A ($1$ valence electron) and Atom B ($7$ valence electrons). Which statement about their reactivity is true?

Atom A is less reactive than Atom B Atom B is stable, but Atom A is highly unstable Both A and B are highly reactive as they seek to achieve the Octet Rule Both A and B are non-reactive due to low ionization energy

36

What is the maximum number of valence electrons required to achieve the typical stable configuration in most elements (excluding the first period)?

$2$ $4$ $8$ $10$

37

Fluorine ($F$), located in Group $17$, has $7$ valence electrons. How does it primarily achieve chemical stability?

By sharing $7$ electrons with another atom By losing $7$ electrons By gaining $1$ electron By losing $1$ electron

38

The electron configuration $2, 8, 8$ represents an element that is:

Highly reactive, needing to gain 1 electron Highly unstable, needing to lose 8 electrons Chemically stable, having achieved the Octet Rule A noble gas, needing to gain 2 electrons

39

Which group of elements is characterized by having $3$ valence electrons?

Alkali Metals (Group 1) Halogens (Group 17) Boron Group (Group 13) Carbon Group (Group 14)

40

Achieving a stable electron configuration (like that of a noble gas) results in a state of:

Higher potential energy and increased reactivity Lower potential energy and decreased reactivity Increased atomic size and decreased stability Neutral charge but high kinetic energy

41

Describe the arrangement of electrons in an atom using the concept of electron shells. Explain the maximum electron capacity for the first three shells (K, L, and M), and state the general formula used to calculate the maximum number of electrons in any principal energy level, $n$.

42

Define valence electrons and explain their critical role in determining the chemical properties and reactivity of an element. Use the concept of the Octet Rule (or Duet Rule) to describe how the number of valence electrons affects an atom's desire for chemical stability.

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