structure and bonding Flashcards
what is an ion?
an atom or group of atoms that has lost or gained electrons and therefore has a positive or negative charge.
what is a covalent bond?
a bond involving shared pairs of electrons between atoms- molecules are held together by covalent bonds
what is metallic bonding?
when positively charged metal ions are surrounded by delocalised outer electrons
what are electrostatic forces of attraction?
strong forces of attraction between oppositely charged particles eg Na+ and Cl-
what bonds do metals and non-metals form?
ionic
what elements form covalent bonds?
non-metals
what elements form metallic bonds?
metals and alloys
what are examples of giant covalent structures?
diamond, graphite, silicon dioxide
what is a monomer?
a small compound whose molecules can join together to form polymers
what is a polymer?
a long molecule consisting of many similar or identical monomers linked together.
what is a limitation of dot and cross diagrams?
they do not show the 3D shape of a molecule
how are group numbers and charges linked?
the group of an element tells us the charge on that atom- eg barium is in group 2 so it has a charge of 2+, iodine is in group 7 so it has a change of -1
what is a giant atomic lattice?
a huge, 3D, regular structure of oppositely charged ions, held together by electrostatic forces.
what is a delocalised electron?
an electron that is able to move freely throughout a structure- enables charge to be carried through
how do ions become positive?
by losing outer shell electrons- number of protons in nucleus > number of electrons in shells