Chemical Bonding Flashcards
Chemical Bond
an attraction between atoms for electrons
A chemical bond involves:
- attraction between nuclei for electrons
- electrons may be lost, gained, or shared when forming a bond
- the # of electrons in a chemical bond is such that each atom fills its valence shell
- 8 electrons fill the valence shell expect H and He only need 2
When a bond is broken..
heat energy is absorbed and it’s an endothermic process
When a bond is formed…
heat energy is released and it’s an exothermic process
When energy is on left.. H2 + I2 + 53 KJ -> HI
more energy is absorbed to break bonds so it’s endothermic
When energy is on right.. H2 + I2 -> H20 + 483.6 KJ
more energy is released in forming bonds so its exothermic
Potential Energy
amount of energy stored within the bonds (distance between the atoms involved in the bond)
When more energy is used to break bonds reaction is (endo) the potential energy
increases
When more energy is used to form bonds reaction is (exo) the potential energy
decreases
with endothermic the…
- potential energy increases
- breaking bonds
- less stable process
- easy to decompose
with exothermic the…
- potential energy decreases
- forming bonds
- more stable process
- hard to decompose
Ionic Bonds
form when metals transfer valence electrons to non-metals
Ionic bonds are formed from the attraction between
positive and negative ions
Ionic Substances are called
ionic compounds not molecules because molecules have neutral particles
Ionic Bond Characteristics
- ionic bonds are very strong
- ions are held in a fixed position in a “crystal lattice structure.”
- ionic compounds are solids at room temp
- they have high melting points and high boiling points