Holt Modern Chemistry Review
CHAPTER 6: CHEMICAL BONDING
The following pages contain the bulk (but not all) of the information for the chapter 6 test.
Focus on this content, but make sure to review class notes, activities, handouts, questions, etc.
If you study this document and NOTHING else, you should at least be able to PASS the test.
***** Test items will be recall, examples, and/or application of this content. *****
OUTCOMES
· Collaborate with peer(s) to understand chemistry content (C C)
· Communicate chemistry content to teacher and peer(s) (E C)
· 6.2: Use the Lewis dot notation, illustrate the covalent bond as the sharing of electrons (F & PK)
· 6.3: List important physical properties of ionic compounds; sum of oxidation numbers = zero (F & PK)
6.1: INTRODUCTION TO CHEMICAL BONDING
· Vocabulary
o chemical bond -- the attractive force that holds atoms or ions together
o ionic bonding -- a force that attracts electrons from one atom to another, which transforms a neutral atom into an ion
o covalent bonding -- a bond formed when atoms share one or more pairs of electrons
o nonpolar-covalent bond -- a covalent bond in which the bonding electrons are equally attracted to both bonded atoms
o polar -- describes a molecule in which the positive and negative charges are separated
o polar-covalent bond -- a covalent bond in which a pair of electrons shared by two atoms is held more closely by one atom
· Chapter Highlights
o Most atoms are chemically bonded to other atoms. The three major types of chemical bonding are ionic, covalent, and metallic.
o In general, atoms of metals bond ionically with atoms of nonmetals, atoms of metals bond metallically with each other, and atoms of nonmetals bond covalently with each other.
6.2: COVALENT BONDING AND MOLECULAR COMPOUNDS
· Vocabulary
o molecule – a group of atoms that are held together by chemical forces; a molecule is the smallest unit of matter that can exist by itself and retain all of a substance’s chemical properties
o molecular compound -- a chemical compound whose simplest units are molecules
o chemical formula -- a combination of chemical symbols and numbers to represent a substance
o molecular formula -- a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms
o electron-dot notation – an electron configuration notation in which only the valence electrons of an atom of a particular element are shown, indicated by dots placed around the element’s symbol
o Lewis structure – a structural formula in which electrons are represented by dots; dot pairs or dashes between two atomic symbols represent pairs in covalent bonds. See examples at right for LEWIS STRUCTURES of NF3 and OCl2
o structural formula -- a formula that indicates the location of the atoms, groups, or ions relative to one another in a molecule and that indicates the number and location of chemical bonds
o single bond -- a covalent bond in which two atoms share one pair of electrons
o multiple bond – a bond in which the atoms share more than one pair of electrons, such as a double bond or a triple bond
o resonance -- the bonding in molecules or ions that cannot be correctly represented by a single Lewis structure
· Chapter Highlights
o Atoms in molecules are joined by covalent bonds. In a covalent bond, two atoms share one or more pairs of electrons.
o The octet rule states that many chemical compounds tend to form bonds so that each atom shares or has eight electrons in its highest occupied energy level.
o Bonding within many molecules and ions can be indicated by a Lewis structure. Molecules or ions that cannot be correctly represented by a single Lewis structure are represented by resonance structures.
6.3: IONIC BONDING AND IONIC COMPOUNDS
· Vocabulary
o ionic compound -- a compound composed of ions bound together by electrostatic attraction
o formula unit -- the collection of atoms corresponding to an ionic compound’s formula such that the molar mass of the compound is the same as the mass of 1 mol of formula units
o polyatomic ion -- an ion made of two or more atoms
· Chapter Highlights
o An ionic compound is a three-dimensional network of positive and negative ions mutually attracted to one another.
o Ionic compounds tend to be harder and more brittle and to have higher boiling points than materials containing only covalently bonded atoms.
6.4: METALLIC BONDING
· Vocabulary
o metallic bonding -- a bond formed by the attraction between positively charged metal ions and the electrons around them
o malleability -- the ability of a substance to be hammered or beaten into a sheet
o ductility -- the ability of a substance to be hammered thin or drawn out into a wire
· Chapter Highlights
o The “electron sea” formed in metallic bonding gives metals their properties of high electrical and thermal conductivity, malleability, ductility, and luster.
IONIC / COVALENT· metal + nonmetal / · nonmetal + nonmetal
· Complete transfer (stealing/donating) of electrons / · Sharing electrons
· Forms ions / · Forms molecules
POLAR / NONPOLAR
· Sharing electrons ≠ (unequally) / · Sharing electrons = (equally)
· 2 different nonmetals / · 2 identical (exact same) nonmetals
· Example: Na+Cl- / · Example: HCl / · Example: H2
· Full ionic charges / · Partial ionic charges / · No charges
· Names with Greek prefixes / · Names with Roman numerals
· Solid at room temperature / · Solid, liquid, or gas at room temperature
· High melting and boiling points / · Low melting and boiling points
· High attraction between particles / strong bonds / · Weak attraction between molecules / weak bonds
· Hard / · Soft
· Good conductors of heat and electricity / · Poor conductors of heat and electricity
· Soluble in water / · Insoluble in water
6.5 Molecular Geometry
1. VSEPR theory -- a theory that predicts some molecular shapes based on the idea that pairs of valence electrons surrounding an atom repel each other
2. hybridization -- the mixing of two or more atomic orbitals of the same atom to produce new orbitals; hybridization represents the mixing of higher- and lower-energy orbitals to form orbitals of intermediate energy
3. hybrid orbitals -- orbitals that have the properties to explain the geometry of chemical bonds between atoms
4. dipole -- a molecule or a part of a molecule that contains both positively and negatively charged regions
5. hydrogen bonding -- the intermolecular force occurring when a hydrogen atom that is bonded to a highly electronegative atom of one molecule is attracted to two unshared electrons of another molecule
6. London dispersion forces -- the intermolecular attraction resulting from the uneven distribution of electrons and the creation of temporary dipoles
o bond energy -- the energy required to break the bonds in 1 mol of a chemical compound
o lattice energy -- the energy associated with constructing a crystal lattice relative to the energy of all constituent atoms separated by infinite distances