chemistry unit 2 Flashcards
what is covalent bonding
metal + non- metal
allotropes definition
different arrangement of the same element
features of diamond (covalent bonding)
-high melting & boiling point
-only made of carbon atoms
-4 covalent bonds for the full shell
graphite features
- high melting & boiling point
-covalent bonding to gain a full shell
alloy definition
a mixture containing one or more metal elements
alloy example
steel
why is iron a soft material
atoms in pure iron is arranged in densely packed layers, these layers can slide, so iron is a soft material
why are alloys like steel stronger than pure iron
when other elements are added to make steel, the atoms distort the regular structure which makes it more difficult for the layer of iron hard to slide over each other
why do metals conduct electricity
delocalized electrons can move freely through the metal structure so the electrons can carry electric charge through the structure. electrical conductivity relies on mobile charge
what is electrostatic forces
it is a force attraction between positive ion and the delicalised electrons, this holds the structure together
why do metals have high melting point and boiling point
this is due to strong attraction between positively charged metal ions and sea of electrons
why can metals conduct heat
this is because delocalized electrons can gain kinetic energy and can move faster to transfer heat. its very efficient
why are metals usually strong & not brittle
they do not break because the delocalized electrons can move freely. this is why metals are malleable & ductile
what is giant ionic structure
lattices of positive & negative ions
why do ionic compounds have high melting and boiling points
strong electrostatic forces of attraction acting between the oppositely charged ions to hold the structure together
- ionic compounds tend to be crystalline and brittle
