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Comparing Atoms. REVIEW. 1 type of matter. 2 or more types of matter. OUR FOCUS in CH 4-7. 1 type of matter. 2 or more types of matter. Copper Lab . Steps 1 - 8. Started out DEEP MAROON / RED Mass crucible 25.078 g Mass of crucible & Cu 26.558 g Heat Copper (2 min) re-mass ????.
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REVIEW 1 type of matter 2 or more types of matter
OUR FOCUS in CH 4-7 1 type of matter 2 or more types of matter
Copper Lab Steps 1 - 8 • Started outDEEP MAROON / RED • Mass crucible 25.078 g • Mass of crucible & Cu 26.558 g • Heat Copper (2 min) re-mass ???? What happened to the mass????
Copper Lab Steps 1 - 8 • Started outDEEP MAROON / RED • Mass crucible 25.078 g • Mass of crucible & Cu 26.558 g • Heat Copper (2 min) re-mass 26.572 g+ + + + Ended solid BLACK A major change!
The red substance “rainbowed”, changed to black and gained mass. These three indicate the substance underwent a • Chemical change • Physical change • Neither
Steps 9-12 • Heat 15 min. longer • Hard solid formed– hard to remove from the bottom of the crucible • Some red still visible on the bottom side – mostly black though
DAY 2 – Part A • Observations: • Some still black and some still red • Red is the original copper that has not reacted. • Black – is copper that reacted with ???? Oxygen in the air
The black and red substance you broke up in the bottom of the crucible and transferred to an empty test tube was • A pure substance • A mixture of substances
The red substance by itself was • A pure substance • A mixture
The red pure substance is a(n) • Element • Compound
Copper An element
The black substance by itself was • A pure substance • A mixture
The black substance by itself is a(n) • Element • compound
Copper II Oxide A compound
2 Cu + O2 2 CuOWhich is/(are) elements? • Cu and CuO • O and CuO • Cu only • O only • CuO only • Cu and O
2 Cu + O2 2 CuOWhich is/(are) compounds? • Cu and CuO • O and CuO • Cu only • O only • CuO only • Cu and O
DAY 2 – Part A • Solution saved for part B • Mass the solid particles remaining from the HCl solution. • Mass – the copper quantity has decreased. • Where is the copper? GREEN Copper now in the Solution NOTE: a completely different phase of matter.
Which substance was soluble in HCl? • Cu – red substance • CuO – black substance • Neither was • Both were
solution unreacted CuO + HCl CuCl2 + H2O + Cu Elements – Cu Compounds - CuO HCl CuCl2 H2O Which is/(are) elements?...compounds?
DAY 2 – Part B • Zinc added to “saved solution” • Bubbles • Bubbles • Bubbles • Color change • Red stuff precipitates • Physical or Chemical Change? Chemical
DAY 2 – Part B • Reaction completed • Observe what is left • Identify - COPPER • Color - REDDISH • Squishy - YES
(Solution) What Happened? Zinc replaces copper in the solution and copper precipitated out CuCl2 + Zn ZnCl2 + Cu
CuCl2 + Zn ZnCl2 + CuWhich is/(are) elements? • CuCl2 and Cu • CuCl2 andZnCl2 • Zn and ZnCl2 • Zn and Cu
CuCl2 + Zn ZnCl2 + CuWhich is/(are) compounds? • CuCl2 and Cu • CuCl2 andZnCl2 • Zn and ZnCl2 • Zn and Cu
(Solution) CuCl2 + Zn ZnCl2 + Cu Zinc replaced copper in the solution
Neither Heating nor other means breaks down copper • ELEMENT • True of all elements! Pure substance with one type of atom. • LIME=?? • 1800 Battery • 1807=H.Davy used battery to decompose (electrolyze) metal oxides (= Ca) • Later Muriatic Acid broken down to find Cl
Today’s Element List • 50 commonly used • 10 = 99% of the mass of the Earth (5=92%) (O,Si,H, Al, Fe, Ca,Na,Mg, Cl,K)
Scientists to Know … CHADWICK THOMSON RUTHERFORD DALTON de BROGLIE BOHR
Bellringer When scientists wanted to find out what an atom was, they were not able to look directly at what the atom was made of. They had to make inferences from the results of many different experiments. It was like trying to describe a picture, such as the one on the next slide, with only small portions visible.
Bellringer, continued 1. Write four sentences describing what you can see of the above picture. 2. What information or parts of the picture would make your descriptions more accurate without revealing the entire picture?
The Beginnings of Atomic Theory • Who came up with the first theory of atoms? .
Democritus • 1st to “think” of atoms • Derived from Greek word – “unable to be divided” (indivisible) • Called them - atomos • 4th century BC Democritus did not have evidence for his atomic theory.
John Dalton • 1808 • Atoms are tiny hard spheres • Created the atomic theory. • All atoms of a given element are alike • Atoms of elements could join to form compounds Educated himself age 12 became a school teacher
Dalton’s Atomic Theory, continued • Dalton used experimental evidence. • Law of definite proportions:Achemical compound always contains the same elements in exactly the same proportions by weight or mass. Dalton’s theory did not fit all observations.
Atomic Theory through Time 400 BC Democritus • John Dalton: • D. Mendeleev: organizes periodic table 1897 JJ Thompson • ErnestRutherford • Niels Bohr 1923 Louis de Broglie 1932 James Chadwick
Because of Mendeleev!!! In 1898 … W. Ramsay and M. Traves find Krypton, Neon and Xenon within 3 months using periodic table
1700s = indirect evidence of atoms • 1st real proof atom’s existed (1905) Einstein calculations of Brownian motion, heat as atomic motion and momentum conservation.
Atomic Theory through Time 400 BC Democritus • John Dalton: • D. Mendeleev: organizes periodic table 1897 JJ Thompson • ErnestRutherford • Niels Bohr 1923 Louis de Broglie 1932 James Chadwick
JJ Thomson • experimented with currents of electricity inside empty glass tubes. • PLAY THE SEGMENT FROM THE CD
JJ Thomson • experimented with currents of electricity inside empty glass tubes. • Discovered • electron in every atom • electrons have a negative charge • “Plum-pudding” model
Ernest Rutherford Geiger and Marsden Lab 18.1 – Gold Foil Experiment PLAY THE SEGMENT FROM THE CD
Rutherford • particles • most passed straight through • Atom mostly empty space ! • some scattered at large angles • Center positively charged nucleus
Niels Bohr Electrons in an atom move in a set path around the nucleus / similar to planets around the sun Electrons orbit the nucleus in fixed orbits Orbits have fixed amount of energy
Louis de Broglie • By 1925 Bohr’s Model was altered. • Electrons behave more like waves on • a vibrating string • analyzed a moving particle as a wave
James Chadwick • Research focused on radioactivity. • With Rutherford – knew there had to be another particle with the proton in the nucleus (missing mass) • discovered neutron • neutrons are the missing mass in the atom
Atom • 1955 • Mueller – Professor at Penn State • 1st to see an atom with an ion microscope • synthetic Metals (???)
Atoms broken down further • Nucleus– Center of atom: Dense • Protons and Neutrons: similar in size and mass • Protons – positive charge • Neutrons – no electric charge • Outside the Nucleus • Electrons – cloud of tiny particles with little mass • Electrons – negative charge (-1) • Size – nucleus : marble – distance to electrons : stadium
Relative Size of Atoms • Atom : Person as Person : Ave. Star • Atom : Apple as Apple : Earth (picture apple full of atoms and then Earth full of apples)