Structure of compunds Flashcards
(28 cards)
What are ionic compounds
Compounds that become crystalline solids at room temperature consist of oppositely charged ions held together by strong electrostatic forces of attraction, arranged in a regular, repeating three-dimensional structure. This is called ionic lattice/crystal lattice
Ionic crystals are represented by what?
empirical formulae/formula units
What are covalent substances are made of what?
These are made of individual molecules that can be either polar or non-polar
How is polarity determined?
By the electronegativity of the atoms present.
What is electronegativity?
The ability of an atom to pull the electrons in a bond towards itself
Polar molecules have at least….
(provide an example too)
partial positive and negative charge ion. For example, H20 and HCl
What is different about non polar molecules than polar molecules?
has atoms with similar or equal electronegativities so there is no polarity in the bond
What is a covalent substance
molecules of covalent bonds are held together by weak intermolecular forces in polar substances and extremely weak intermolecular substances in non-polar substances.
What is simple molecular crystals? (State 2 examples)
These compounds have a molecular lattice that have a weak intermolecular force of attraction held together in a 3-d, repeating shape.
Example:
Iodine
Dry ice
Glucose
Ice
What type of particles make up ionic solids?
They are made up of ions held together by ionic bonds
What type of particles make up simple molecular solids?
Molecules with strong covalent bonds within atoms and weak intermolecular forces of attraction.
How is the melting point of ionic solids compared to simple molecular solids?
Ionic solids have a high melting point; simple molecular solids have a low melting point.
Do simple molecular solids conduct electricity?
None at all
When do ionic solids conduct electricity?
When molten or dissolved in water
Are simple molecular solids soluble in water or organic solvents?
Most are soluble in non-polar organic solvents but insoluble in water (except glucose, which dissolves in water).
Do ionic solids conduct electricity when solid?
Nope
Are ionic solids soluble in water or kerosene?
A soluble in polar solvents like water, but not soluble in non-polar solvents like kerosene.
What is the melting point difference between ionic and simple molecular solids
Ionic solids melt at high temperatures; simple molecular solids melt at low temperatures.
What type of formula represents giant molecular crystals?
Empirical formulae
A giant molecular lattice with strong covalent bonds between non-metal atoms in a regular, 3D arrangement.
Is the structure of giant molecular crystals
What is an allotrope?
A different form of a single element in the same physical state.
What are diamond and graphite in relation to carbon?
They are allotropes of carbon.
Give three examples of giant molecular crystals.
Graphite, diamond, silicon dioxide
What type of electrons are found in graphite and what do they do?
Delocalized electrons that move within the lattice
