Electron Shells and Bonding - Practice Flashcards

Flashcards covering electron shells, valence electrons, periodic trends, bond types, electronegativity, polarity, hydrogen bonds, Van der Waals interactions, and example molecules (water, ammonia, methane, NaCl).

What is the closest electron shell to the nucleus called?

The K shell (also known as n=1).

What is the last electron shell called, and what are the electrons there called?

The valence shell; valence electrons.

What determines whether an atom is reactive or not?

Reactivity is determined by the electrons in the valence shell; atoms with incomplete valence shells tend to react to achieve stability.

What is the general formula for the maximum number of electrons in shell n?

2n^2 (the formula is sometimes misquoted in slides, but 2n^2 is the correct expression).

What are the two main types of chemical bonds you can form between atoms?

Ionic bonds (transfer of electrons) and covalent bonds (sharing of electrons).

What is a covalent bond?

A bond formed by the sharing of electrons between atoms.

What is an ionic bond?

A bond formed by transferring electrons from one atom to another, creating ions (cation and anion).

What determines bond polarity in covalent bonds?

The electronegativity difference between the bonded atoms; nonpolar if difference is less than 0.4, polar if difference is between 0.4 and about 1.8.

What is electronegativity?

The tendency of an atom to pull electrons toward itself in a bond.

What is a dipole in a molecule?

A molecule with partial positive and negative ends due to unequal sharing of electrons.

Which molecules are typically nonpolar?

H2, O2, and CH4 are typically nonpolar due to symmetry or identical atoms.

Why is water polar?

Oxygen is more electronegative than hydrogen, and lone pairs on oxygen create a bent shape with partial charges, making water polar.

How do hydrogen bonds form?

A hydrogen atom bonded to a highly electronegative atom (F, O, or N) forms an interaction with another electronegative atom in a different molecule.

What are Van der Waals (London dispersion) forces?

Weak intermolecular forces arising from transient dipoles between nonpolar molecules; important for adhesion and other phenomena.

Give an example of an ionic compound and explain the formation.

Sodium chloride (NaCl); Na donates an electron to Cl, forming Na+ and Cl-, which crystallize into an ionic lattice.

Give an example of a covalent molecule with carbon forming bonds to hydrogen and its octet behavior.

Methane (CH4); carbon forms four covalent C–H bonds to complete its octet (carbon has four valence electrons).

What rule governs the number of electrons around an atom’s valence shell, with hydrogen as an exception?

Most elements seek a full octet (8 electrons) in their valence shell; hydrogen is satisfied with 2 electrons in its first shell.

How can you classify a bond as polar versus nonpolar based on electronegativity difference?

Nonpolar covalent bonds have small or no electronegativity difference (<0.4); polar covalent bonds have a difference between ~0.4 and ~1.8.

What is a noble gas and a key property relevant to bonding?

Noble gases have full valence shells and are generally nonreactive; they do not readily form bonds with other elements.