1
what is a covalent bond?
a bond between two non-metals that share the same atoms
what holds the electrons together in a covalent bond?
attraction between oppositely charged particles
monatomic?
1 atom/ they habe fuller outer shell/ dont usually form molecules with other atoms/ unreactive / noble gases
diatomic?
two of the same atoms/ (halogens) most stable when in paired form/ 2 atoms bonded in their natural state
what is a molecule?
a collection of electronically bonded atoms
gas test for hydrogen
lighted splint in test tube containing gas. if gas is hydrogen - sqeaky pop - because H burns quickly in O2 + releases heat energyj
gas test for oxygen
glowing splint held at open end of test tube. if tube contains O2 the splint will relight
gas test for carbon dioxide
bubbling gas thru limewater. if carbon dioxide is present the limewater will turn colourless -> cloudy milk water. ( formation calcium carbonate turns limewater milky
structure of molecule-shapes of covalent compounds
H-Cl. h-c
c
covalent network substances
Boron, Carbon and Silicon
low boiling points-covalent molecular substances
covalent molecular substances- weak intermolecular forces so small amount of energy to break bonds-low boiling
high boiling points-covalent networks
ALL covalent network structures have high melting points bc many strong covalent bonds would need energy to break the strong bonds
nitrogen in atmosphere
78%
oxygen in atmosphere
21%
other gases in atmosphere
1%
what other gases are in the atmosphere
Argon, Neon, Helium, Krypton, Xenon, Hydrogen
carbon dioxide
>0.4%
water vapour
>0.4%
carbon dioxide
>0.4%
sulphur dioxide
trace / exists in small amounts
atomic number
number of protons in an atom
mass
protons + neutrons
why are atoms neutral
they have equal numbers of protons and electrons
subatomic particles - list
electrons, neutrons, protons
periodic table arranged
rows-periods. columns-groups
alkali metals - group 1
very reactive w air + water, has to be stored in oil, easy to cut, as u go down reactivity increases
halogens - group 7
very reactive non-metals, as u go down reactivity increases
noble gases - group 0/8
unreactive gases, colourless gases, denser than air, 2nd lightest element - helium. ALL found in air