Electron Configuration | MCQs

Explanation

• The shielding effect decreases across a period.
• This is because the increasing nuclear charge is not fully counterbalanced by the same number of inner electrons, resulting in a weaker shielding effect.

Explanation

When the 6d orbital is completely filled, the next electron enters the 7p orbital.

This is based on the Aufbau principle, which dictates that electrons first occupy the lowest energy levels available.

After the 6d orbitals (which can hold up to 10 electrons) are filled.

The 7p orbitals (which can hold up to 6 electrons) become the next lowest energy.

Explanation

For 2p orbitals, the principal quantum number (n) is 2.

The azimuthal quantum number (l) for a p-orbital is 1.

So, n = 2, l = 1 is correct.

Explanation

• Lone pairs are electron pairs that are not shared by atoms in a covalent bond.
• They are pairs of electrons that are localized on a single atom and are not involved in bonding.
• Lone pairs are also known as non-bonding pairs or free pairs.

Explanation

• Group VIA (also known as Group 16) elements have six electrons in their valence shell.
• Oxygen (O) is a member of this group, and its atomic number is 8.
• The electronic configuration of oxygen is 1s2 2s2 2p4, which shows that it has six electrons in its valence shell (two in the 2s orbital and four in the 2p orbitals).

Explanation

• A non-metal atom forms an anion (a negatively charged ion) by gaining one or more electrons.
• This means that the atom acquires additional electrons to form a negative ion.

Explanation

• Noble gases are stable because their outermost energy level is full, meaning they have eight electrons in their valence shell.
• This full outer energy level gives them a stable electronic configuration, similar to that of the noble gases, and makes them unreactive.

Explanation

• When one atom loses an electron to form a cation and another atom gains that electron to form an anion, the resulting attraction between the oppositely charged ions is an ionic bond.
• This type of bond is typically formed between a metal and a nonmetal, and is characterized by a transfer of electrons rather than a sharing of electrons (as in covalent bonds).

Explanation

• The octet rule states that atoms tend to gain, lose, or share electrons to achieve a full outer energy level, which typically corresponds to eight electrons in the valence shell.
• This rule is a fundamental principle in chemistry and is used to explain the formation of chemical bonds and the structure of molecules.

Explanation

• Magnesium (Mg) is an alkaline earth metal that loses two electrons from its outer shell to form a divalent cation (Mg²⁺).
• This means that it typically loses two electrons to form compounds, resulting in a valency of +2.