Topic 1 structure and bonding Flashcards
what is a covalent bond?
a shared pair of electrons between 2 atoms
what is a molecule
a group of atoms held together by covalent bonds
why do simple covalent molecules form gases with low melting and boiling points?
weak intermolecular forces holding the molecules together are easy to break
why are giant covalent structures solids with high melting and boiling points?
all atoms are held together by strong covalent bonds which are difficult to break
what is an ionic bond?
the electrostatic attraction between a positive and negative ion
what happens in ionic bonding
a metal gives its electrons to a non metal. The metal becomes the positive ion and the non metal becomes negative
why are ionic compounds able to conduct electricity when molten/dissolved?
because it’s ions are free to move
why do ionic compounds have high melting points?
ions are held in a lattice with lots of strong ionic bonds which are difficult to break
describe the structure of an ionic compound
ionic compounds form lattices which are regular arrangements of positive and negative ions
what’s an allotrope
different structure of the same element
what’s an isotope
different mass, same element
3 properties of a non metal
low melting point
dull
brittle
properties of metals
high melting points
shiny
malleable
in an ionic compound what happens to the metal
looses electrons and becomes positive
in an ionic compound what happens to the non metal?
gains electrons and becomes negative
