Chemical Bonds Flashcards
1
Q
When do atoms bond?
A
- To become more stable
- Bond has to be more stable than the individual atoms
- Less potential energy in bonding
2
Q
Types of bonds
A
3
Q
Electronegativity
A
- A measure of the tendency of an atom to attract a bonding pair of electrons
- No units - not energy
- A : B
- Who wants these pairs of e- more?
4
Q
Predicting bond type from EN differences
A
- If difference = 0, electrons equally shares, no EN
- EN = asymmestrical
5
Q
Ionic bonding
A
- Metal of low IE
- Nonmetal of high EA
- A metal atom can transfer an e- to a nonmetal
- The resulting cation and anion are attracted to each other by electrostatic forces
- Large clusters - lattice
- Simplest ratio - formula unit
6
Q
Crystal lattice
A
- Colors - transition metals
- Cubic
7
Q
Formula units
A
- Formula of an ionic compound represents the ratio of cation to anion in the crystal
- If 8 Ca+2 ions, there are 16 F- ions
8
Q
Lewis structures of ionic compounds
A
9
Q
Coulomb’s Law
A
- As ion charge increases, the attractive force increases
- As the distance between ions increases, the attractive force decreases
10
Q
Importance of Coulomb’s Law
A
*
11
Q
Lattice energy
A
*
12
Q
Size vs ionic bond strength
A
*
13
Q
Why are ionic compounds brittle?
A
*
14
Q
Why are ionic compounds soluble in water?
A
*
15
Q
When and why do ionic compounds conduct electricity?
A
*
16
Q
Covalent bonding
A
- Results when atoms share pairs of e- to achieve an “octet:
- Electrons that are shared by atoms are called bonding pairs
- Electrons that are not shared by atoms but belong to a particular atom are called lone pairs (nonbonding pairs)
17
Q
Electron sharing
A
- The bond arises from the mutual attraction of 3 nuclei for the same electrons
- Electron sharing results
- Bond is a balance of attractive and repulsive forces
- Most stable when attractive forces = repulsive forces
18
Q
Covalent bond formation (overlap)
A
- Covalent bond can result from a “head-to-head” overlap of atomic orbitals on neighboring atoms
19
Q
Bond length vs stability
A
- A bond forms when atoms are a certain distance away from each other
- At this distance, the atoms are in a low energy state
- If they are closer together or farther apart, they will be in an unstable situation
20
Q
Bond length and bond energy
A
- Bond length is the distance between bonded atoms at their minimum potential energy (the average distance between two bonded atoms)
- Bond energy is the energy required to break a chemical bond and form neutral isolated atoms
