Structures of compounds Flashcards
What are ionic crystals
These compounds exist as crystalline solids at room temperature. They are represented by an empirical formula
What are covalent substances?
They are made of individual molecules that can either be polar or non polar.
What determines polarity?
It is determined based on the electro negativity of the atoms present.
What is electronegativity
It is the ability of atoms to pull electrons in a bond towards it self
What are polar molecules?
They have atleast one molecule that is partially negative and partially positive.
What are examples of polar molecules?
water and hydrochloric acid
What are non polar molecules?
They have atoms with similar or the same electro negativity and has no polarity in the bond.
What holds covalently bonded compounds together.
weak intermolecular forces in polar molecules and even weaker intermolecular forces in non polar moelcules.
What are simple molecular crystals?
They have a molecular lattice that have a weak intermolecular force of attractiom that holds small molecules in a regular 3d arrangmenent.
examples of simple molecular crystals
ice
dry ice
iodine
glucose
What is the structure of ionic solids and simple molecular solids?
Ionic solids- ions are held together by ionic bonds
simple molecular solids- has molecules with strong covalent bonds and weak intermolecular forces of attraction.
What is the melting point of ionic solids and simple molecular solids?
ionic- high
simple molecular- low
Solubility of ionicand simple molecular solids.
ionic- soluble in polar solvents like water but not in non polar like kerosine
molecular- most are soluble in non polar organic solvents but insoluble in water except glucose.
Conductivity
ionic- does not conduct as a solid but does conduct whe molten or dissolved in water.
molecular- does not conduct at all
what are Giant molecular crystals?
They are in a giant molecular lattice that have strong covalent bonds between non metals ina 3d arrangement.
What are examples of giant molecular crystals?
diamond and graphite
What are allotropes?
different forms of a single element in the same physical state. they have the same chemical properties since they are from the same element but different physical properties because they are bonded differently.
What is the structure of diamond?
each carbon atom is bonded to 4 others in a tetrahedron arrangment.
What is the structure of graphite?
Each carbon atom is bonded to three others in hexagonal rings which are bonded to form layers. Each layers are held togetheer by weak intermolecualr forces.
The molecule also has delocalised electrons that move within the lattice.
