Chapter 6 Chemistry

use the concept of potential energy to describe how a covalent bond forms between two atoms.

As the atoms approach each other, the electron/proton attraction is stronger than the electron-electron and proton-proton repulsion. The atoms are drawn to eachother, lowering the potential energy. Eventually, a distance is reached at which the repulsion between the like charges equals the attraction of the opposite charges. Then, the potential energy is at a minimum and a stable molecule forms.

how can electronegativity be used to distinguish between an ionic bond and a covalent bond?

If the difference in electronegativity is greater than 1.7, the bond is ionic. anything less is covalent.

describe how a covalent bond holds two atoms together

a pair of electrons is attracted to both nuclei of the two atoms bonded together

what property of the two atoms in a covalent bond determines whether or not the bond will be polar?

electronegativity

what two factores determine whether or not a molecule is polar?

electronegativity and molecular geometry

the notation for sodium chloride, NaCl, stands for one ___.

formula unit

Atoms with a strong attraction for electrons they share with another atom exhibit________.

high electronegativity

name two elements that are exceptions to the octet rule.

hydrogen and boron

A chemical bond that results from the electrostatic attraction between positive and negative ions is called an ___.

ionic bond

The greater the electronegativity difference between two atoms bonded together, the greater the bond's percentage of ___.

ionic character

what is the VSEPR theory?

it predicts the shape of atoms

what type of energy best represents the strength of an ionic bond?

lattice energy

In a crystal of an ionic compound, each cation is surrounded by a number of _____.

negative ions

If two covalently bonded atoms are identical, the bond is identified as _____.

nonpolar covalent

A chemical bond between atoms results from the attraction between the valence electrons and ____ of different atoms.

nuclei

what is the major assumption of the VSEPR theory?

pairs of electrons repel each other

A covalent bond in which there is an unequal attraction for the shared electrons is _.

polar covalent

if electrons involved in bonding spend most of the time closer to one atom rather than the other, the bond is __.

polar covalent

Why are resonace structures sometimes used instead of Lewis structures?

resonance structures can show location of electrons in a bond better than Lewis structures.

A covalent bond consists of __.

shared electron pair.

describe the electron distribution in a polar-covalent bond and its effect on the partial charges of the compound

the electron density is greater around the more electronegative atom, giving that part of the compound a partial negative charge. The other part of the compound has an equal partial positive charge.

in water, 2 hydrogen atoms are bonded to one oxygen atom. why isn't water a molecule?

the electron pairs that are not involved in bonding also take up space, creating a tetrahedron on electrol pairs and making the water molecule bent.

describe the force that holds two ions together in an ionic bond.

the force of attraction between unlike charges hold a negative ion and a positive ion together in an ionic bond.

what orbitals combine together to form sp3 hybrid orbitals around a carbon atom>

the s orbital and all three p orbitals

the electrons involved in the formation of a chemical bon are called ___.

valence electrons