covalent bonds Flashcards
what is a covalent bond
atoms share electrons with each other so that they have got full outer shells
where does covalent bonding occur
compounds of non-metals and in non-metal elements.
what happens when non-metal atoms bond together
they share pairs of electrons to make covalent bonds
how do you show the bonding in covalent compounds
dot and cross diagrams and structural formula (lines -)
where do atoms share electrons
only in their outer shells (highest energy levels)
draw a dot and cross diagram to show the bonding in a molecule of ammonia (NH3)
(in book)
draw a structural formula to show the bonding in a molecule C2H6
(in book)
what are simple molecular substances
made up of molecules containing a few atoms joined together by covalent bonds.
what are the common example that i should know
hydrogen (H2), chlorine (Cl2), oxygen (O2), nitrogen (N2), methane (CH4), water (H2O), hydrogen chloride (HCL)
properties of simple molecular substances
very strong covalent bonds, but forces of attraction between these molecules are very weak.
what states of matter are molecular substances at room temp.
gases or liquids
how do you melt or boil a simple molecular compound
only need to break these feeble intermolecular forces and not have covalent bonds. so the melting and boiling points are very low, because the molecules are easily parted for each other.
what happens when molecules get bigger
strength of intermolecular forces increases, so more energy is needed to break them, and the melting and boiling point increases
why do molecular compounds not conduct electricity
because they aren’t charged, so there are no free electrons or ions
