Electronegativity & Bonding - 3.1

Flashcards covering electronegativity concepts, trends, and bond formation.

What is electronegativity?

The ability of an atom to attract a pair of electrons towards itself in a covalent bond.

Which scale is used to assign electronegativity values to atoms?

The Pauling scale.

How does electronegativity trend across a period and down a group?

Increases across a period; decreases down a group.

Which element is the most electronegative on the periodic table and what is its Pauling value?

Fluorine, 4.0.

Why are bonding electrons in the C–F bond closer to fluorine?

Because fluorine is more electronegative and attracts electron density more strongly.

Name the main factors affecting electronegativity.

Nuclear charge, atomic radius (distance), and shielding by inner electron shells.

How does increasing nuclear charge affect electronegativity?

More protons increase the attraction on bonding electrons, increasing electronegativity.

What is atomic radius?

The distance between the nucleus and the outermost electrons.

How does increasing atomic radius influence electronegativity?

Generally decreases electronegativity because bonding electrons are farther from the nucleus.

What is shielding (electrons masking the nuclear charge)?

The masking effect of inner electron shells that reduces the attraction of the nucleus on outer electrons.

How does shielding affect electronegativity?

Increased shielding reduces nuclear attraction on bonding electrons, decreasing electronegativity.

Why is sodium more electronegative than caesium?

Sodium has fewer electron shells and less shielding, leading to stronger attraction for bonding electrons.

What is the trend of electronegativity down a group?

Electronegativity decreases down a group.

What is the trend of electronegativity across a period?

Electronegativity increases across a period.

How are nuclear charge, shielding, and atomic radius related to electronegativity?

Higher nuclear charge tends to increase electronegativity; greater shielding or larger atomic radius lowers it; trends depend on these factors.

Where on the periodic table is electronegativity highest?

At the top right of the periodic table.

How can you predict bond type from electronegativity differences?

Difference: < 1.0 → covalent; 1.0–2.0 → polar covalent; > 2.0 → ionic.

In a polar covalent bond, which atom carries the δ− charge?

The more electronegative atom.

In a non-polar covalent diatomic molecule, how is electron density distributed?

Equally shared between the two atoms.

What happens when there is a large electronegativity difference in a bond?

Electrons are transferred to the more electronegative atom, forming an ionic bond.

What is a cation?

A positively charged species formed when an atom loses electrons.

What is an anion?

A negatively charged species formed when an atom gains electrons.

What threshold on the Pauling difference indicates an ionic bond?

Difference greater than 2.0.

What threshold on the Pauling difference indicates a covalent bond?

Difference less than 1.0.

What range of electronegativity difference indicates a polar covalent bond?

Difference between 1.0 and 2.0.