Electron Shell Model and Chemical Bonding

Vocabulary flashcards covering key concepts from the lecture notes on electron shells, electronegativity, and types of chemical bonds.

Valence electron

Outermost electrons in an atom's shell involved in bonding; determine how many bonds an atom can form.

Electronegativity

The power of an atom to attract electrons in a bond (not the atom's overall charge).

Pauling electronegativity scale

A scale introduced by Linus Pauling to quantify and compare an atom's ability to attract electrons.

Difference in electronegativity

The difference between two atoms' electronegativity values; guides the type of chemical bond formed.

Nonpolar covalent bond

Covalent bond with approximately equal sharing of electrons; small electronegativity difference (diff < 0.5).

Polar covalent bond

Covalent bond with unequal sharing of electrons; moderate electronegativity difference (diff 0.5–1.4).

Ionic bond

Bond formed when electrons are transferred from one atom to another, creating ions held together by electrostatic attraction (large electronegativity difference).

Hydrogen bond

Electrostatic attraction between partial opposite charges; commonly occurs between water molecules, holding them together and is stronger than van der Waals.

Hydrophilic

Water-loving; polar or charged molecules that can dissolve in water.

Hydrophobic

Water-hating; nonpolar molecules that cannot form hydrogen bonds with water and tend to be insoluble in water.

Van der Waals forces (London dispersion forces)

Weak, temporary attractions due to instantaneous dipoles; important for interactions between nonpolar molecules and in biology.

Methane (CH4)

A nonpolar molecule with four C–H covalent bonds; carbon forms four bonds and achieves a full outer shell.

Water (H2O)

A polar covalent molecule where oxygen is more electronegative than hydrogen; forms hydrogen bonds and has a stable full outer shell.

Sodium chloride (NaCl)

An ionic compound formed by electron transfer from sodium to chlorine, creating Na+ and Cl− held by electrostatic attraction.

Octet rule

Atoms tend to bond in order to achieve a full outer electron shell, typically eight electrons for second-period elements.