P1 1g covalent bonding Flashcards
what is a covalent bond?
two or more atoms sharing electrons
how is a covalent bond formed?
when two atoms can share electrons so both can have a full outer shell
how do you use dot and cross diagrams for covalent bonds?
dot for one element cross for the other, drawn like a Venn diagram, bit in the middle shows shared electrons
what are the substances covalent bonds make?
- simple molecular substances
- polymers
- giant covalent structures
what are the intermolecular forces like between the molecules?
weak intermolecular forces, only between each individual molecule
are the covalent bonds strong?
yes very
what are polymers?
long chains of monomers
what are giant covalent structures?
arranged in a regular lattice, hydrogen bonds
what is the electrostatic attraction like in covalent bonds?
strong electrostatic attraction between the shared pair of electrons and the nuclei of the atoms involved (electrons are negative and nuclei is positive)
do simple covalent bonds conduct, why?
no, because they do not contain free moving electrons
why do simple molecular structures have low melting and boiling points
weak intermolecular forces acting between neighbouring molecules
why are most small molecules gases or liquids at room temp?
forces are very weak
why does the melting and boiling point increase?
because the relative molecular mass of a substance increases, and more energy is required to break the bonds and there are more intermolecular forces between them
what happens when a covalent molecule boils?
the intermolecular forces are broken but not the covalent bonds, hence water not turning into hydrogen and oxygen
what is a giant covalent structure like?
- very strong covalent bonds
- high melting and boiling points
- don’t conduct electricity
