Notes on Primrose Kitten Chemistry

Memorize these:

carbon dioxide	CO₂
water	H₂O
oxygen gas	O₂
hydrogen gas	H₂
nitrogen gas	N₂
ammonia	NH₃
hydrochloric acid	HCl
sulfuric acid	H₂SO₄

Equations

nitrogen gas + hydrogen gas → ammonia
H₂ + N₂ → NH₃
balanced equation: N₂ + 3H₂ → 2NH₃

methods of separating mixtures

distillation, separate liquids with different boiling points
evaporation, separate liquids from solids
filtration, separate liquids from solids
fractional distillation, separate by different sizes and boiling points

1908-1913: Working under Rutherford, Geiger and Marsden executed the Gold Foil experiments at the University of Manchester. Before this, we had plum pudding model of an atom. Positive and negative charge was distributed uniformly throughout a substance. Fired an alpha particle at a gold foil. Most particles went right through. Some were deflected. Some bounced back. From this, they deduced that each atom has a nucleus where all positive charge and most mass is clustered.

1932: Chadwick discovered the existence of neutrons, also working under Rutherford.

Periodic Table
Groups give us number of electrons in the outer shell
Periods give us number of shells

Na, sodium has 11 electrons, 2,8,1
The single electron has a tendency to wander off, leaving an ion with 10 electrons.

F, florine, has 9 electrons, 2,7
The outer shell is short one electron, so it tends to gain one.

Sodium floride

Elements in group 1 tend to form +1 ions
group 2: +2 ions
group 6: -2 ions
group 7: -1 ions
group 8: stable

metals on the left-hand side form positive ions
non-metals, right-hand side, from negative ions

1863, 56 known elements, new elements discovered at one per year

1868: Mendeleev developed the first proper periodic table. He saw it in a dream. published in textbook <i>Principles of Chemistry</i> (two volumes, 1868–1870)

by mass
left gaps, able to predict missing elements
groups by similar properties

group 8 or 0	noble gasses	unreactive	full outer shell	increased boiling point as you move down the group
group 1	alkali metals	very reactive	only 1 electron on outer shell	reactivity increases as you move down the group
group 7	halogens	very reactive	7 electrons on outer shell	generally found in diatomic molecules (F₂, Cl₂, Br₂) Florine gas, Chlorine gas, Bromine gas; reactivity decreases as you move down the table, melting points and boiling points increase; more reactive halogens will displace less reactive halogens in a reaction

transition metals
typical
properties: hard, shiny, conductive of heat and electricity
can be used in building bridges, saucepans, wires
copper: blue
iron (ii): green
iron (iii): red/brown