Transcript Elements and the Periodic Table

Chemical Building Blocks
Chapter 3 – Elements and the
Periodic Table
Section 2 -
Modeling Atoms
• Atoms are too small to see, so scientists need
models!
• Model = diagram, mental picture, math
statement, or object that helps explain ideas
about the natural world.
DO NOW
•How are the letters of
the alphabet similar to
the elements?
• COMBINATIONS OF 26 LETTERS make
up every word in the English language.
• Similarly, all material things in the world are
composed of different combinations of about
100 different elements.
• An element is a substance that cannot be
broken down into simpler substances through
ordinary chemistry--it is not destroyed by
acids, for example, nor changed by electricity,
light, or heat.
• http://www.nclark.net/PeriodicTable
Dmitri Mendeleev
Russian Scientist –
worked w/ 63 known
elements.
Used melting point,
density, color, atomic
mass, and chemical
bonds to look for patterns
in the elements.
Noticed properties of
elements repeated, and
put elements in groups.
Predicted new elements
with specific properties
would be discovered.
** Atomic mass = the average mass of all the isotopes of that element.
Modern Periodic Table
• Element properties repeat “periodically”
• Arranged according to atomic number (# of
protons) [Thanks to Henry Moseley in 1913]
EACH ELEMENT:
• Has it’s own square, and:
• 1. atomic number
– (# of protons)
• 2. chemical symbols and names
– First letter capitalized, followed by 1 or 2 more
letters
– Some symbols are based off of Latin names
• Ex: Pb = lead = plumbum, Au = gold = aurum, Na =
sodium = natrium
• 3. average atomic mass
Organization of Periodic Table
ROWS
COLUMNS
-Aka Families
-properties change as you move left to right
-Members have similar characteristics
-Less reactive as you move right
-7 of them
-Normally named after first element in each
group (ex: carbon family and nitrogen family)
-All of the elements in a period have the same
number of atomic orbitals
-EX:
-Group 1 react violently w/ water
-Group 2 reacts slowly or not at all w/
water
-Group 18  rarely react
DO NOW
• Look at the aluminum foil, the aluminum
container, and the aluminum can.
• List as many properties of aluminum as you
can think of.
• Compare the shapes, thickness, and general
appearance of the objects.
• What would happen if you tried to bend and
unbend each object.
METALS
• Physical Properties =
– 1. shininess
– 2. malleability
• Able to be hammered or rolled thin into flat sheets and
other shapes
– 3. ductility
• Able to be pulled out into a long wire
– 4. conductivity
• Ability to transfer heat or electricity to another object
5. All but Mercury are solids at
room temp
Iron in Cereal
• http://www.youtube.com/watch?v=V265pGgs
BnM
METALS, continued
• Chemical Properties
– 1. Reactivity
• The ease & speed w/ which an element combines, or
reacts, w/ other elements
– Some are EXTREMELY reactive
– Others HARDLY react
– http://www.youtube.com/watch?v=92Mfric7JUc&feature=relate
d
– Corrosion = the gradual wearing away of a metal
element because of a chemical reaction
Corrosion
With your partner
• Be able to label on periodic table where your
metals are located.
• Give examples of properties of your metals
• Give common uses of your metals.
ALKALI METALS
• http://www.youtube.com/watch?v=m55kgyAp
YrY
• http://www.youtube.com/watch?v=PyFLvSg6Z
Dw
Alkali Metals
• Group 1
• React by losing 1
electron
• Super reactive – always
combined with other
elements in nature
• Shiny and soft
Alkali Metals, cont’d
Facts about Alkaline Earth
Metals
• Group 2
• Good conductors
• React by losing 2
electrons
• Fairly hard, gray-white
• A little less reactive
than alkali
Alkaline Earth Metals
Facts about Transition Metals
• Groups 3 – 12
• Mostly familiar metals
– (iron, copper, nickel)
• Mostly hard and shiny
• Many form colorful
compounds
• Not as reactive as 1st 2
groups!!
Transition Metals
Metals in Mixed groups
•
•
•
•
•
•
•
Aluminum
Gallium
Indium
Thallium
Tin
Lead
Bismuth
Metals in Mixed Groups
DO NOW
• Look at Page 84.
• What are the bottom two rows of elements
called?
• Why are they below all of the others ?
• What is significant about elements 93 –
102?
RARE EARTH ELEMENTS
What groups did we talk about so far??
http://periodictable.com/
LANTHANIDES
Why do you think they are called
“lanthanides” ??
- Hint: Look at your periodic table on page 84!!!
Are lanthanides Metals or
Nonmetals?
Lanthanides
• Soft metals…. (what do we know about them
if they are metals???)
• Mixed with more common metals to make
alloys
– Alloy = a mixture of a metal with at least one
other element, usually another metal
• Normally found combined with each other!
Alloys
Alloys - Continued
Lanthanides
Where do we see LANTHANIDES
in everyday life???
- Lanthanum = Used in flints for lighters
and in electron microscopes.
Praseodymium = used by
glassblowers
Cerium = used in lighter flints, catches fire easily
when struck, used for sparking special effects
Neodymium = used in alloys to
make very powerful permanent
magnets …used in headphones,
disk drives, motors
Actinides
Actinium - Can be used to generate intense heat!
The rock probably contains just a few
atoms of protactinium at any one
time….but it’s the best we can do! It is
hard to acquire
-The Actinides are mostly radioactive.
-Uranium is used in nuclear power plants to produce energy.
- Nuclear reactors used to power submarines too!
http://www.youtube.com/watch?v=fjgdgAh
OzXQ
Actinides
A radioactive button like
this is inside most smoke
detectors.
A trace of americium
creates charged particles
that betray the smoke.
Americium is thus the only
man-made element
available in grocery
stores.
Actinides in Real Life
•
Two major types of atomic bombs by US during World War II.
1. A uranium-based device ( “Little Boy”)
1. A plutonium-based device ( “Fat Man”).
•
The uranium-based Little Boy device became the first nuclear weapon used in war when it
was detonated over the Japanese city of Hiroshima on 6 August 1945.
•
Exploding with a yield equivalent to 12,500 tons of TNT, the blast and thermal wave of the
bomb destroyed nearly 50,000 buildings and killed approximately 75,000 people.
•
Initially it was believed that uranium was relatively rare, but within a decade large deposits of
it were discovered in many places around the world.
http://www.youtube.com/watch?v=fWoNDxjOksM&feature=related
http://www.youtube.com/watch?v=Xs3JE4WRL-8&feature=related
•
•
Synthetic Elements
Elements higher than 92 were man-made when
nuclear particles were forced to crash into one
another. Very Unstable.
- Particle accelerator = move atomic nuclei
at very high speeds
- Curium = first synthetic element
Particle Accelerators
• Particle accelerators  they move atomic nuclei
faster and faster until they have reach very high
speeds. If different elements collide fast enough,
they might combine!
• First synthesized element was Curium – made in
Chicago! Curium provides power for some
equipment on the Mars Rover
SOOO…..
• What are the 2 bottom rows of the periodic
table called?
– 1.
• Like to form alloys!!!! ^
– 2.
• Radioactive and unstable
• How do scientists make elements that are
heavier than uranium?
NONMETALS
• Most are:
– poor conductors
– reactive with other elements.
• Solid nonmetals are dull and brittle , not
malleable, not ductile
• 10 are gases, a few are solid, 1 is liquid
Nonmetals – Chemical Properties
• Most are reactive and readily form
compounds
– Fl = most reactive element!
• They gain/share electrons when reacting w/
other atoms
• Metals GIVE electrons, nonmetals GAIN
electrons
– SALTS =metal + nonmetal
• Nonmetals together share electrons
Families of Nonmetals
•
•
•
•
•
•
1. Carbon Family
2. Nitrogen Family
3. Oxygen Family
4. Halogen Family
5. Noble Gases
6. Hydrogen
CARBON
FAMILY
Carbon is in all living things!!!! There are many forms carbon can be found in.
(coal, gasoline, diamonds)
C
Si
Ge
Sn
Pb
Nitrogen Family
N (nitrogen)
P (phosphorus)
As (arsenic)
Sb (antimony)
Bi (bismuth)
Nitrogen
• Rarely found in nature as a single atom. Rather,
Nitrogen atoms join to each other.
N
N—N
N
N—N
N
N—N
• It is 80% of the atmosphere! Plants convert Nitrogen to a
usable form, and we get it from plants!
Phosphorus
Reactive, found in compounds, used in
matches
Oxygen family
O (oxygen)
S (Sulfur)
Se (Selenium)
Te (tellurium)
Po (polonium)
Oxygen reacts with almost every element and
is highly abundant.
Oxygen in air  lungsbloodbody
We breathe O2 (O—O)
Ozone = O3 (O—O—O)
it screens out harmful radiation from
the sun
http://www.heatingoil.com/blog/weekheating-oil-march-19-sulfur-heating-oil318/
Halogen Family
• Fluorine, chlorine, bromine, iodine, astatine
• Form salts
• Dangerous when not combined, but useful
within compounds
Noble Gases
• UNREACTIVE!!
• In very small amounts in the atmosphere
Hydrogen
• Simplest and smallest!
• One proton and one electron in every atom… some
have neutrons.
• >90 % of atoms in universe, but only a small
fraction of the mass because they are sooo small!
• H2O = most common
Metalloids
• Characteristics of metals and
nonmetals
• Silicon = most common
• In sand and glass
• * Varying ability to conduct electricity
• Semiconductors
• Conduct electricity under some conditions and
not others
Homework
• Page 105 Section 4 assessment
• Do the At-Home Activity
ELEMENTS
FROM STARDUST!
• Where do elements come from?
• Why are some common and some rare?
• Scientists look to the stars!
THE SUN
Mostly Hydrogen… at tremendously high
pressure and temperature!
~ 15 MILLION degrees Celsius
Plasma
• Under those extreme conditions, matter
is not solid , liquid, or gas.
• Instead, it is PLASMA!
• Plasma = state of matter with gas-like
mixture of free electrons and atoms stripped o
electrons
– Stars
– Comets
– Fluorescent lights (plasma w/o the
pressure)
– Create light in TVS
Remember:
• Nuclei are made up of __________ and
___________ and therefore have a _____(+ or
- ) charge.
When Nuclei
Combine
• Nuclei NORMALLY repel each other.
– BUT…Stars have high pressure, and nuclei
are squeezed close together
– NUCLEAR FUSION = 2 atomic nuclei combine to
form a larger nucleus, releasing huge amounts of
energy
• Occurs on a large scale in stars, and heavier
elements are created!
New Elements from Fusion
Rememb
er: what
is an
ISOTOPE
?
In the sun,
isotopes of
hydrogen
fuse to
produce
helium,
and HUGE
amts of
energy
Sun has
enough
H to fuel
itself for
5 billion
years
Hydrogn

helium

heavier
element
s like
carbon
NEBULA
A star eventually
shrinks, and its
elements spread
out into space and
looks like a
cloudlike region of
gases.
Elements from Large Stars
• Large stars get super hot (hotter than the
sun!), and produce larger and larger elements
(up to IRON)
• In final hours, star undergoes a SUPERNOVA
– A huge explosion that breaks apart a star
– 1 billion degrees Celsius
– Enough energy for fusion to create the heaviest
elements (pg 111)
– http://www.youtube.com/watch?v=eE8QkBlyf5k