Ionic and Molecular Compounds Flashcards
What are the two types of chemical bonds?
ionic compounds and molecular compounds
What is a chemical bond?
the force of attraction holding two atoms or ions together in a compound
What forces hold together ionic bonds and what is their arrangement?
many ionic forces - electrostatic forces)
- arranged in a giant lattice structure (regular gird-like arrangement)
What are ionic compounds composed of?
metal and non meal
What are the characteristics of ionic compounds?
- hard and brittle
- relatively high melting and bioling points
- conduct electricity as molten liquids
- conduct electricty when dissolved in water (electrolytes)
Explain the high melting point in ionic compounds
ions are held together by strong electrostatic forces which are hard to break apart
Why are ionic compounds hard?
the bonds in crystal lattive resist being stretched
Why are ionic compounds brittle?
when an external force strikes the crystal lattice, the distribution of ions is disrupted and alike charges may now become side by side creating a repulsive force and breaking them apart.
What is an electrolyte?
when a free floating ions are dissolved in a liquid that can then carry elecctric charges.
AS A SOLID, ionic compounds cannot conduct electricity because their ions are bonded in a lattice.
- Ions have either a positive or negative charge
- there is a transfer of electrons between atoms to create an ionicc bond
There is no single unit made up of a single sodium and chloride ion -> THERE ARE NO MOLECULES OF NACl
what is a formula unit
the smallest repeating unit in an ionic crystal
what is an ionic compound composed of
composed of a huge number of formula units
What must you put around an ion?
SQUARE BRACKETS (and charge)
What are molecular compounds composed of?
two or more non-metals
What are the characteristics of molecular compounds?
- can be solid, liquid or gas
- solids can be soft, waxy, flexible or crystalline
- low melting/boiling points
- poor electric conudctivity when dissolved in water
- poor electrical conductivity in the liquid state
Molecular compounds form Molecules
Explain the melting/boiling points in a molecular compound.
the force of attraction between moleccules is lower than an ionic bond
Why can’t molecular compounds conuduct electricity
there are no ions formed, there is limited ability to cconduct electricity
Spearmint and Caraway have the same elements and quantity of elements, but they are flipped and are completely different substances
What is a molecular element?
a pure substance composed of molecules made up ot two or more atoms of the same element (diatomic)
what is a molecular compound
a pure substance composed of molecules usually made up of two or more non-metallic elements (like water)
what is bonding capacity
the number of covalent bonds an atom can form. The bonding capacity is usually equivalent to the number of unpaired electrons in the valence shell of an atom
What is a resonance structure?
when a double (multiple) bond can be on multiple places on a molecule
what is the equation for formal charge?
formal charge = # of valence electrons -# of unbonded ele ctrons - (#of unbonded electrons/2)
For neutral molecules, the sum of the formal charges must add up to zero
For ions, the sum of formal charge must equal the charge of the ion.
formal charges DO NOT indicate actual charge separation witthin a molecule, just helps us keep track of valence electrons in molecule
If a lewis structure is a non-zero formal charge, try to change the structure such that it is 0
