1g - covalent bonding Flashcards
what is the difference between covalent bonds and ionic bonds?
covalent: electrons are shared between atoms
ionic: electrons are transferred from one atom to another
what is the short straight line between two atoms?
a covalent bond
what is a covalent bond?
a chemical bond where atoms share pairs of electrons with each other
what are intermolecular forces
the weak forces of attraction between individual molecules in a covalent substance.
do covalent bonds involve the sharing of electrons?
yes
what type of element forms a covalent bond?
non-metals
what is formed when a group of two or more atoms covalent bond together?
a compound / molecule
what are dot and cross diagrams used to represent?
small covalent molecules with a fixed number of atoms
what does simple molecular mean?
a small covalent molecule with a fixed number of atoms
what are diatomic molecules?
molecules composed of two atoms.
what are inorganic molecules?
simple molecules that don’t contain carbon atoms
what is an organic molecule?
a simple molecule that contains carbon and hydrogen atoms
what are simple molecular structures?
small molecules with covalent bonds, which have weak forces between molecules
why are covalent compounds generally bad conductors of electricity?
they don’t have free ions or electrons to carry the charge
what happens to melting and boiling as the relative molecular mass of a substance increases
they increase because of the increased number of electrons and stronger intermolecular forces.
what are insulators?
materials that don’t allow the flow of electric charge or heat
why do simple molecular structures have low melting and boiling points?
because of the weak intermolecular forces which need small amounts of energy to break
what are allotropes?
different structural forms of an element, like diamond and graphite being different structural forms of carbon.
why does diamond not conduct electricity?
there are no freely moving charged particles to carry the current
what are fullerenes?
a group of carbon allotropes that consist of molecules forming hollow tubes or spheres.
name 3 points about the structure of graphite
- each carbon atom is bonded to three others
- there are hexagonal layers
- there is one free/delocalised electron per carbon atom
name three points about the properties of diamond
- it doesn’t conduct electricity
- has a high melting point
- extremely hard.
what are 3 properties of graphite?
- conducts electricity and heat
- high melting point
- soft and slippery
what are 3 points about the structure of the buckminster fullerene?
- it is a hollow sphere
- each carbon atom is bonded to three others
- there is 1 free/delocalised electron per carbon atom
