Major Points and Concepts
bond-- a force that holds groups of two or more atoms together and makes them functional as a unit
bond energy-- the energy needed for breaking a bond
ionic bonds-- the attraction between a strongly positive ion and a strongly negative ion
covalent bond-- a bond is form between atoms with electrons are shared by the nuclei
ionic compound-- a compound that is formed by an ionic bond [for example, a metal (+) and a nonmetal (-)]
polar covalent bond-- a bond in which a pair of electrons is shared in common between two atoms, but the pair is held more closely by one of the atoms, making it unequal
electronegativity-- the relative ability of an atom in a molecules to attract shared electron to itself
dipole moment-- the product of magnitude of charge on a molecule and the distance between two charges of equal magnitude with opposite sign
**In almost all stable chemical compounds of representative elements, all of the atoms have achieved a noble gas electron configuration.
Lewis structure-- a representation of a molecule that shows how the valence electrons are arranged among atoms in the molecule
bond energy-- the energy needed for breaking a bond
ionic bonds-- the attraction between a strongly positive ion and a strongly negative ion
covalent bond-- a bond is form between atoms with electrons are shared by the nuclei
ionic compound-- a compound that is formed by an ionic bond [for example, a metal (+) and a nonmetal (-)]
polar covalent bond-- a bond in which a pair of electrons is shared in common between two atoms, but the pair is held more closely by one of the atoms, making it unequal
electronegativity-- the relative ability of an atom in a molecules to attract shared electron to itself
dipole moment-- the product of magnitude of charge on a molecule and the distance between two charges of equal magnitude with opposite sign
**In almost all stable chemical compounds of representative elements, all of the atoms have achieved a noble gas electron configuration.
- ionic compounds tend to form small crystals
- ionic compounds are solid at room temperature
- ionic compounds have low thermal conductivity
Lewis structure-- a representation of a molecule that shows how the valence electrons are arranged among atoms in the molecule
valence electrons-- electrons on the outer shell
**representative metals form ions by losing enough electrons to achieve the configuration of the previous noble gas
**nonmetals form ions by gaining enough electrons to achieve the configuration of the next noble gas
**representative metals form ions by losing enough electrons to achieve the configuration of the previous noble gas
**nonmetals form ions by gaining enough electrons to achieve the configuration of the next noble gas
- a single bond involves two atoms sharing one electron pair
- a double bond involves two atoms sharing two pairs of electrons
- a triple bond involves two atoms sharing three electron pairs
resonance-- a molecule shows resonance when more than one Lewis structure can be drawn for the molecule
Example Calculations
Test yourself:
1. What is bond energy?
2. What is a covalent bond?
3. Label each of these bonds as covalent, polar covalent, or ionic: a) K--Cl b) Br--Cl c) Cl--Cl
4. Give the total number of valence electrons in each of the following molecules: a) B2O3 b) CO2 c) CBr4 d) C2H2
5. draw a Lewis dot structure for the following: a) C2H6 b) CHCl3 c) C2H4Cl2 d) N2H4
Answers:
1. Bond energy is the energy required to break a chemical bond.
2. A covalent bond exhibits the sharing of electrons between nuclei.
3. a) ionic b) polar covalent c) covalent
4. a) 24 b) 16 c) 20 d) 17
5.
1. What is bond energy?
2. What is a covalent bond?
3. Label each of these bonds as covalent, polar covalent, or ionic: a) K--Cl b) Br--Cl c) Cl--Cl
4. Give the total number of valence electrons in each of the following molecules: a) B2O3 b) CO2 c) CBr4 d) C2H2
5. draw a Lewis dot structure for the following: a) C2H6 b) CHCl3 c) C2H4Cl2 d) N2H4
Answers:
1. Bond energy is the energy required to break a chemical bond.
2. A covalent bond exhibits the sharing of electrons between nuclei.
3. a) ionic b) polar covalent c) covalent
4. a) 24 b) 16 c) 20 d) 17
5.