Transcript What is hydrogen peroxide?

Unit Three
Elements and the Periodic Table
HE ATOM
T
The smallest part of an
element that has
properties of that
element.
In 1981, a type of microscope called a scanning tunneling
microscope (STM) was developed.
STM image of a single zigzag chain of cesium atoms (red) on a galliumarsenside surface (blue)
Photo courtesy National Institute of Standards and
Technology (NIST)
<http://www.howstuffworks.com/framed.ht m?parent=at
om.htm&url=http://nist.gov>
Copper
atoms
nanotechweb.org/article s/ne
ws/3/9/8/1/niststm1
MODEL
A way scientists explain
something unknown by
relating it to something that
can be seen or understood.
What are some reasons scientists use models?
You have certainly had experience with models
in science in your past. Name one of the
models you have used in science class.
Why is our current understanding of the atom still
considered a model or a theory?
Model of an
atom.
Empedocles (49- 432 BCE) argued that all matter was composed of four
elements: fire, air, water, and earth. The ratio of these four elements
affected the properties of the matter.
Atomic Model Timeline
Democritus
2500 years ago
First idea of an atom
"atomos" (invisible)
Democritus
He suggested that atomos were eternal and could not
be destroyed.
Democritus theorized that atomos were specific to the
material that they made up, meaning that the atomos of
stone were unique to stone and different from the
atomos of other materials, such as fur.
This was a remarkable theory that attempted to explain
the whole physical world in terms of a small number of
ideas.
Alchemy
Middle Ages, 1200-1600
Goal was to change cheap elements into gold
Philosopher’s Stone
The philosophers' stone is a legendary alchemical
substance, said to be capable of turning base metals ,
especially lead , into gold; it was also sometimes believed
to be an elixir of life , useful for rejuvenation and possibly
for achieving immortality .
The Scientific Revolution
1600-1700’s
Copernicus-the Sun is the
center of the Solar System.
Galileo-advanced
telescopes &
experimental
physics
NewtonLaws of Motion &
Gravity
John Dalton
early 1800’s
“Father of the
Atomic Theory”
John Dalton
School Teacher from England
19th Century (1807)
He combined the idea of elements with the
Greek theory of atoms.
Dalton’s Atomic Theory
All matter is made of atoms
Atoms can’t be created or destroyed
All atoms of one element are the same
Atoms of different elements can combine to form new substances
John
Dalton pictured the atom as a hard sphere with the same
makeup throughout the entire atom.
William Crookes
English Scientist 1870's
Tested Dalton's theory of the atom.
Experimented with an airless glass tube with two metal pieces
hooked to a battery.
Cathode ray tube + CRT
Same type of mechanism found in tv's and computer monitors
Saw a "beam" of something from the negatively charged cathode to the
positively charged anode.
The beam looked like a grennish-yellowish light, but Crookes said it was a
beam of particles.
He couldn't prove it!!! (bummmer!)
J. J. Thomson
1897 English physicist
Worked on Crooke's experiments. Use a magnet next
to the glass tube.
Proved that the beam was not light...Light can not be
bent with a magnet.
The beam bent towards the magnet.....Opposite
charges attract.
Knew that the particles were negatively charged.
HOW?
Named the negatively charged particles ELECTRONS.
"Plum Pudding Model of the Atom"
J J Thomson's model of the atom.
Your assignment: write in the symbols for each of the
elements, and learn them.
Quiz on the elements will be next week.
Element Name Symbol
Aluminum _____
Antimony _____
Argon _____
Arsenic _____
Barium _____
Beryllium _____
Bismuth _____
Boron _____
Bromine _____
Calcium _____
Carbon _____
Chlorine _____
Chromium _____
Cobalt _____
Copper _____
Fluorine _____
Gallium _____
Germanium _____
Gold _____
Helium _____
Hydrogen _____
Iodine _____
Iron _____
Krypton _____
Lead _____
Element Name Symbol
Lithium _____
Magnesium _____
Manganese _____
Mercury _____
Neon _____
Nickel _____
Nitrogen _____
Oxygen _____
Phosphorus _____
Platinum _____
Plutonium _____
Potassium _____
Radon _____
Selenium _____
Scandium _____
Silicon _____
Silver _____
Sodium _____
Sulfur _____
Tin _____
Titanium _____
Tungsten _____
Uranium _____
Vanadium _____
Zinc _____
Element Name Symbol
Aluminum Al
Antimony Sb
Argon Ar
Arsenic As
Barium Ba
Beryllium Be
Bismuth Bi
Boron B
Bromine Br
Calcium Ca
Carbon C
Chlorine Cl
Chromium Cr
Cobalt Co
Copper Cu
Fluorine F
Gallium Ga
Germanium Ge
Gold Au
Helium He
Hydrogen H
Iodine I
Iron Fe
Krypton Kr
Lead Pb
Element Name Symbol
Lithium Li
Magnesium Mg
Manganese Mn
Mercury Hg
Neon Ne
Nickel Ni
Nitrogen N
Oxygen O
Phosphorus P
Platinum Pt
Plutonium Pu
Potassium K
Radon Rn
Selenium Se
Scandium Sc
Silicon Si
Silver Ag
Sodium Na
Sulfur S
Tin Sn
Titanium Ti
Tungsten W
Uranium U
Vanadium V
Zinc Zn
Ernest Rutherford
1906 considered the father of nuclear physics
Won the 1908 Nobel Prize in Chemistry
Wanted to see if Thomson's model of the atom was correct......
Set up an experiment that fired fast moving positively charged
bits of matter (alpha particles) at a thin piece of a metal such as
gold.
Alpha partices come from unstable atoms. They are positively charged, and so they are
repelled by particles of matter which have a positive charge (opposites attract, like repell).
Rutherford hypothesized that the gold film did not contain enough matter to stop the speeding
alpha particle or change its path...........
The unexpected results of the experiment
caused Rutherford to realize that
Thomson's model was incorrect,
and he proposed his own model.
Rutherford's model included a
nucleus in the atom.
The positively charged proton is located in the very small space at the center of an
atom.
Most of the atom is empty space occupied by nearly massless electrons.
Electrically neutral particles, neutrons are also located in the nucleus.
The number of electrons equal
the number of protons in an atom.
Neils Bohr 1913
Electrons are in energy levels
Erwin
Schrodinger
1926
Electron Cloud
Model
electron orbitals
shapes
have
James
Chadwick
1932
Discovered the neutron
Nuclear Power First atomic bomb-1945
Atomic Energy The secrets of the atom’s
nucleus is unveiled
The science of atomic radiation, atomic change and nuclear fission was
developed from 1895 to 1945, much of
it in the last six of
those years.
Over 1939-45, most development
focused on the atomic bomb.
was
From 1945 attention was given to harnessing this energy in a
controlled fashion for naval propulsion and for making
electricity.
Since 1956 the prime focus has been on the technological
evolution of reliable nuclear power plants.
Uranium was discovered in 1789 by Martin Klaproth, a German
chemist, and named after the planet Uranus.
Hints for Learning the Element Symbols
Au - Aey U ! Give me my gold !
-or- Autumn leaves turn to gold.
Na - Na, I don’t want sodium on my food.
(think of salt, NaCl)
Ag - Aged people have hair of silver.
Fe - Females need iron.
Hg - The planet Mercury is huge.
Pb - Plumbers use lead pipes.
Cu - C U (see you) later, copper !
Sn – Cut tin with tin-snips.
Pu – P U ! Plutonium stinks.
Sb – Antimony is so bad for you.
The symbol is the first two
letters of the element name.
Al Aluminum
Ar Argon
Ba Barium
Be Beryllium
Bi Bismuth
Br Bromine
Ca Calcium
Co Cobolt
Ga Gallium
Ge Germanium
He Helium
Kr Krypton
Li Lithium
Ne Neon
Ni Nickel
Sc Selenium
Sc Scandium
Si Silicon
Ti Titanium
The element symbol is only the
first letter of the element name.
B Boron
C Carbon
F Fluorine
H Hydrogen
I Iodine
N Nitrogen
O Oxygen
P Phosphorous
S Sulfur
U Uranium
V Vanadium
The
symbol is from a foreign
The symbol is the first letter of the
word for that element, usually
element name plus one other letter in Greek or Latin.
that name.
Sb Antimony
Au Gold
Cl Chlorine
Ag Silver
Cr Chromium
K Potassium
As Arsenic
Hg Mercury
Mg Magnesium
Na Sodium
Mn Manganese
W Tungsten
Pt Platinum
Sn Tin
Pu Plutonium
Pb Lead
Rn Radon
Fe
Iron
Zn Zinc
Cu Copper
Gold
Palladium
Iron
Silver
Mercury
Copper
Zinc
Krypton
Aluminum
Lithium
Sodium
Neon
Helium
Magnesium
Nikel
Fluorine
Tin
Coblt
Lead
Bariium Bromine
Sodium
Sulfur
Argon
Chlorine
Radium
Silicon
Calcium
Radon
Fluorine
Beryllium
Chlorine
Plutonium
Iodine
Boron
Li
He
Pb
Ag
Ca
Li
S
Ne
Os
Kr
Cl
Ba
Pu
P
F
K
Co
N
Sr
Sn
Fe
Si
Cu
C
Br
Al
Hg
Be
O
H
Rn
Ra
He
Mg
Au
Element symbol test tomorrow!
Use your flash cards and
be ready for it!!
Welcome Mr. Koy!
What
is hydrogen peroxide?
What is the chemical forumla for it?
Hydrogen peroxide is an oxidizer commonly used as a bleach. It is a clear
liquid , slightly more viscous than water, that appears colorless in dilute
solution.
It is used as a disinfectant , antiseptic , oxidizer, and in rocketry as a
propellant. The oxidizing capacity of hydrogen peroxide is so strong that it is
considered a highly reactive oxygen species .
H2O2
Lab: Observing the element OXYGEN Hour ___________ Date __________
Objective: To collect and observe a sample of oxygen.
Materials: Safety glasses, 2 standard test tubes, test tube rack, 3 wood splints,
manganese dioxide (MnO2), distilled water (H2O), hydrogen peroxide (H2O2), matches,
graduated cylinder (10 mL), test tube clamp
Procedure:
Use CLEAN, DRY test tubes. With a pencil, mark one tube “w” for water. Mark the
other tube “h” for hydrogen peroxide.
Put 7 mL distilled water in the tube marked “w”. Put 7 mL hydrogen peroxide in the
test tube marked “h”.
3. Complete the table below.
Substance
Water
Hydrogen
Peroxide
State of matter
Color
Observable
differences?
4. Use a wooden splint to add the manganese dioxide to each of the two test tubes.
Put in 1 splint-full. Record your observations below.
Substance
Observations when mixed
with MnO2
Water
Hydrogen Peroxide
5. Use a new wood splint. Light the splint with a match. Let the splint burn 3 seconds,
then blow out the flame. A small area on the splint will continue to glow orange. Move the
glowing splint down into the tube marked “w,” but DO NOT let it touch the liquid. This is
called a splint test. Observe and record below.
6. Add one more splint-full of manganese dioxide to the “h” tube. Put your thumb over
the test tube and shake gently. Repeat the splint test procedure on this tube. Observe
any differences in the glowing splint carefully. Record below.
Substance
Water
Hydrogen
Peroxide
Formula
Splint test
observation
s
Model/Drawi
ng
QUESTIONS TO ANSWER
Look at the formulae for water and hydrogen peroxide. What elements are in each of these compounds? __________________________
and _______________________________
Which substance, water or hydrogen peroxide, has more oxygen atoms? ___________________
Oxygen is the gas that bubbled out of the tube with hydrogen peroxide. Write two properties of oxygen.
____________________________________ ______________________________________
The air we breathe contains about 19% oxygen, 79% nitrogen, and 2% carbon dioxide. Is air a MIXTURE or an ELEMENT?
__________________________________
Oxygen is one of those elements sometimes confused when students write chemical symbols. Using a lower case letter for the second
letter of an element’s abbreviation or symbol is important. Write the element or elements shown by each of the symbols below.
Co _______________________________
C O _____________________ ________________________
P O _____________________ ________________________
Pu _______________________________
P U _____________________ _______________________
S I ______________________ _______________________
Si _______________________________
Ni _______________________________
N I _____________________ _______________________
C U ____________________ _______________________
Cu ______________________________
Please use a complete sentence to explain one thing you learned by doing this lab today.
_____________________________________________________________________________________________ __________________
_____________________________________________
________________________________________________