module two: foundations in chemistry Flashcards
atoms consist of
nucleus - protons, neutrons
electrons - occupied a region outside the nucleus arranged in shells
mass of an electron
1/1836th mass of a proton
isotope
atoms of the same element with different numbers of neutrons and different masses
relative isotopic mass
the mass of an isotope relative to 1/12th of the mass of carbon-12
relative atomic mass
the weighted mean mass of an atom relative to 1/12th of the mass of carbon-12
atomic orbital
region around the nucleus that can hold up to 2 electrons with opposite spins
shape of s-orbital
spherical
shape of p-orbital
dumbell
simple molecular elements
H2, N2, O2, F2, Cl2, Br2, I2, P4, S8
metallic elements
Mg, Fe, Na, Ni
giant covalent elements
diamond, graphite (carbon)
Si
simple molecular compounds
CO2, CO, NO2, NO, SO2, SO3, NH3, CH4, H2S
giant covalent compounds
SiO2
pV = nRT
p = pressure (Pa)
V = volume (m^3)
n = number of moles
R = gas constant (8.314)
T = temperature (K)
metal + acid
salt + hydrogen
metal oxide + acid
salt + water
metal carbonate + acid
salt + water + carbon dioxide
strong acid
fully dissociates in water
releases all its hydrogen atoms
e.g. HCl, HNO3
weak acid
partially dissociates in water
releases a small proportion of its hydrogen atoms
e.g. CH3COOH
why do covalent bonds have low melting/boiling points
little energy is req. to overcome the weak intermolecular bonds between the separate molecules
conductivity in ionic compounds
cannot conduct electricity in solid state as ions ar immobile and cannot carry a charge
can conduct electricity when molten or aqueous as ions are free to move and carry a charge
why do ionic compounds have high melting/boiling points
high temperatures are needed to prove the large amount of energy req. to overcome the strong electrostatic attraction between the ions
why do ionic compounds dissolve in water
water is polar
polar water molecules break down the lattice and surround each ion in solution
shape of:
2 bonding pairs, 0 lone pairs
linear
CO2
