Transcript 5 wiki notes

Things to know, symbol, atomic
number, atomic weight, stairstep,
s,p,d,f
areas. Period, group, column family
The creators of the table
 Dobereiner arranged by property into
triads, relying heavily on atomic mass
 Newland noticed that properties tend to
repeat every 8, called them octets ( we
still use the octet rule today, which says
properties repeat in a recognizable
pattern, see the table we have
The first actual table
 Mendeleev is our main guy!
 He put atoms together by characteristics,
arranged them all in a way they are easier to
learn. He focused
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1st on characteristic,
2nd on atomic mass
Left places for atoms not yet found
Predicted element characteristic
He was right in Many cases!!
It wasn’t until after all this
that atomic number was
discovered, and there was
very little rearranging
needed
 Go Mendeleev!!!
Periodic Law- know it,
don’t break it
 States that properties of elements
reoccur in a given pattern.
 When elements are arranged in their
atomic number order, those patterns can
be seen.
Group 1- alkali metals
 1st row of the periodic table, these are
very reactive metals, they are not found
in nature alone.
 Soft, silvery, not dense
 Used in human chemistry,
 Li is a medicine
 More reactive farther down the list
Group 2 alkaline earth
metals
 Still soft, silvery metals, but harder,
denser and stronger than group 1
 Too reactive to find alone in nature, but
less explosive than group 1
 Called earth metals because found in the
soil, in jewels (Be), in the ocean ( Mg ), in
rocks (Ca)
 Great for fireworks and flares ( Sr, Ba)
Hydrogen and Helium
 Group 1 and group 2, but not included in
alkali and alkaline metals!
 Why? Because they are gases!
 Colorless, odorless gases, H is very
reactive, He is totally nonreactive ( full
valance shell)
 Hydrogen in the air, Helium, in the
ground in Texas
Transition metals
 Also called D block
metals, all have s2 in
common
 These are the classic
metals
 Dense
 Solids ( not mercury)
 Lustrous
 Found as elements in
nature
 Malleable ( bendable)
 Ductile ( turn into wires)
 Conduct and heat and
electricity
What do we do with
metals?
 Build stuff like houses, buildings, cars, cans,
Industry!!!( Iron and others) tools weapons
 Wiring for EVERYTHING! ( copper)
 Need trace amounts to carry oxygen, make
your muscles and nerves work
 Jewelry gold and silver, platinum, titanium
 Money silver and gold, nickel, zinc and copper
 Light bulbs ( tungsten)
Metalloids/ semi metals
 Groups 1-12, and parts of 13 are metals
 Groups 18,17, and parts of 15,14,are
nonmetals
 in between, along the stair step, are 7
metalloids, so named because they have
characteristics of metals and nonmetals.
 They include, B, Si, Ge, As, Sb, Te, Po
 Solids, but they are brittle, not all shiny, but
some are, and they are semi conductor (
conduct, but slowly)
Uses for metalloids
 Semi conductors in computers, cell
phones, calculators, PDA’s etc.
 silicon- Implants, insulation, caulk,
 Arsenic- poison white crystal solid, looks
like sugar,
 Useful in rat poison, natural substance
P block nonmetals
 Elements in groups 13-16
 Some solids,liquids and gases
 Most are reactive, many are found in organic
compounds ( of living things)
 Carbon is the backbone of living things,
oxygen is not only in compounds but
elemental in all living things, N and P and S
are found throughout living organisms.
 They vary in color from black (C)
 S is yellow, P can be red or yellow , N and O
are colorless odorless gases.
Halogensgroup
17not in
 Most reactive nonmetals,
they are
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nature as elements.
All are poisonous as elements, but very
useful in compounds
F- keeps your mouth clean, found in water
Cl- cleaner for pools, concrete, industry, is a
heavy green gas
Bromine is a red liquid, also very heavy,
iodine is a purple crystalline solid, both
useful for killing bacteria and fungi in
compounds, poisonous to humans in
elemental form
Useful in photography, insecticides and lights
Nobel gases
 Group 18( see red
column)
 All gases
 Full valance shell, so do
not react
 Useful to pack reactive
substances for shipping
 Very high burn point so
used in welding
 Also useful for lights
(Neon lights !)
Lanthanides and actinides
 The 4F’s are Lanthanides – a group of very
similar very dense metals. Not used for too
much, they are so similar they are hard to
separate
 The 5f’s are actinides, only the first four are
natural, the rest are man made, all are
radioactive. Useful for treating cancers and
diseases, tracing elements through natural
systems ( water ways and rivers) Used for
nuclear energy and bombs.
Trends of the periodic table
 These are certain characteristics that
show a definite pattern across the
periodic table. It is useful to help figure
which atoms do what, which atoms are
useful in certain situations
 1st atomic radius! Size of the atom.
 As you go down the PT, the atoms get
larger
 ( should make sense, they have more shells)
 As you go across, they get smaller
 I know that is weird, but more protons in the
same shell pull them in closer
Trend 2 Ionic radius
 An ion is an atom that has gained or lost an
electron
 If an atom has 4 or less valance electrons, it
loses them ( groups 1-14)
 Makes the atom smaller – called a cation
 Left of metalloids get smaller
 When they lose electrons, they become positively
charged. ( have more protons than electrons)
 Atoms with more than 4 valance electrons
gain electrons
 Makes the atoms larger, call them anions
 Have a negative charge
Some examples
 sodium metal Na wants to lose one electron.
 Mrs. Holtmeyer leaves it out. There is oxygen
in the air. O wants to… gain 2 because it
already has 6!
 2 Na and O get close, and Na gives electrons
to the O!!! Na+ and O-, and opposites
attract, so they are now stuck together in a
compound called Na2O. CaO
Trend 3 Ionization energy
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Energy to lose electrons
The easier it is, the less energy it takes
Less energy on left, more on the right
More energy on the top, less on the
bottom
trend 4! Electron affinity
 The opposite of ionization energy, this is
energy to gain electrons
 More energy on the left, less on the right
 Less energy on the top, more on bottom
 If electrons are VERY easy to add, the #
is negative!
 For instance if you had an electron affinity
of –567 kJ. This means energy leaves the
reaction
Trend 5 Electronegativity
 Much like e. affinity, this is the ability of
atoms to hold onto BONDED e-.
 Very useful, numbers 0-4 have been
assigned to represent, with 4 being the
most electronegative. F is a 4. Trend
follows just like ionization, Flourine is
highest and Francinium is lowest