Test 2 – Chemistry Answers

Flashcard maker : Carol Rushing
independent of the amount of substance present (ex: density, color boiling point)
intensive physical property
dependent upon the amount of substance present (ex: length, volume, mass)
extensive physical property
What four elements did the Greeks believe in in 400 BC?
wind, earth, fire, water
Democritus and Leucippos used what word to describe the small, individual particles that possibly made up matter?
Why did divisibility of matter hang in the balance for the next 2000 years?
due to lack of experimentation options by Greeks
extraction of metals from ores (Bauer) and medicinal applications of minerals by Paracelsus in the 16th century
Who was the first quantitative chemist that performed pressure/volume gas experiments and expanded the element list?
Stahl suggested that what flowed out of burning materials,t things stopped burning if the air in container became saturated with this substance?
The theory of “phlogiston” was changed after who discovered oxygen by heating Mercuric (Mercury II) oxide (decomposition)?
What is the highest honor even by the American Chemical Society?
Priestly Medal
What are the most important contributions to science that Priestly made?
discovered carbon dioxide and disolved in water to from seltzer, found graphite was an electrical conductor, and discovered oxygen
Who performed many combustion experiments, formulated the law of conservation of mass, wrote the first modern chem textbook, is known as the “father of modern chemistry,” and was guillotined by the French in 1794?
mass is neither created nor destroyed, but may change forms
law of conservation of mass
Wh developed the law of definite proportions?
a given compound always contains exactly the same ratio of elements by mass
law of definite proportions
Who discovered the atomic theory?
when 2 elements form a series of compounds, the ratios of the masses of the second element that combine with one gram of the first element can always be reduced to small whole numbers
law of multiple proportions
who helped determine the absolute formulas of compounds?
Gay-Lussac and Avogadro
What were Gay-Lussac’s main contributions to science?
pressure/temperature of gases, codiscoverer of boron, process of manufacture sulfuric acid, developed glassware we use in labs
at the same temp and pressure, equal volume of different gases contain the same number of particles
Avogadro’s hypothesis
Who used the cathode ray tube to discover the negatively charged electron and the charge to mass ratio of an electron?
JJ Thomson
high voltage to the negative electrode or cathode gave off particles that repelled the negative pole
cathode ray tube
What model did Thomson use for his discovery?
Plum pudding model
Who performed the oil drop experiment in 1909 where x rays produced charges?
Robert Millikan
What is the charge of an electron?
1.602 x 10^-19 Coulombs
mass of an electron
9.11 x 10^-31 kg
What did Rutherford use radioactivity to discover?
positively charged nucleus of the atom
Who discovered radioactivity when a mineral containing uranium produced an image on a photograph plate in the absence of light?
Which of Rutherford’s experiments involved firing a beam of positively charged alpha particles at at his metal foil?
gold foil experiment
What happened during the gold foil experiment?
most of the particles passed straight through the foil, but some were deflected straight back
What did the gold foil experiment disprove?
Thomson’s model of the atom
Where is most of the atom’s mass contained?
in the nucleus which is a dense center of positive charge with electrons moving around the nucleus in the most empty space of the atom
Who named the alpha, beta, and gamma particles, coined the term half life, and invented the name proton for the nucleus of the hydrogen atom?
What is the mass of a proton and neutron? (about the same)
1.67 x 10^-27 kg
What is alike and different about the numerical charge of the electron and proton?
they are the same, but one is negative and the other is positive
atoms with the same number of protons but different numbers of neutrons so mass differs
symbol for atomic number
symbol for mass number
What is the number of protons in the nucleus
atomic number
number of protons and neutrons in the nucleus
mass number
forces that hold atoms overhear in compounds
chemical bonds
formed b a sharing of electrons
covalent bonds
atom or group of atoms that has a net positive or negative harge
positive ion (metals)
negative ion (nonmetals)
give and take of electrons, occurs when oppositely charged particles join
ionic bond
groups of atoms with a single charge
polyatomic ion
Atomic number
whole number
mass number
decimal number (bc average of all the isotopes of that element)
Where are metals found on the periodic table?
What happens to metals?
they tend to I’ve up their outer shell electrons a de become positive ions, conduct heat and electricity, are malleable, ductile, and have luster
What are nonmetals found on the periodic table? (except Hydrogen)
What tends to gain electrons and become negative ions?
elements in the same vertical columns that have similar chemical properties because they aha the same number of valance electrons
groups or families
valence electrons
outer shells
group 1A
alkali metals (except hydrogen)
group 2A
alkaline earth metals
group 17 or 7A
halogens (salt former)
group 18 or 8A
Noble gases (full outer shell fo electrons, prefer tobe inert or unreactive)
horizontal rows of elements
protons and neutrons found in nucleus
term for each isotope of each atom
What happens to form a more stable nucleus?
radioactive nuclei decay or decompose
How is a nuclide less radioactive?
the closer the proton to neutron ratio
All nuclides with 84 or more protons are what?
unstable and radioactive
How many unknown nuclides are there?
about 2000
How many unknown nuclides are stable with respect to radioactive decay?
Which element has the largest number of stable isotopes and how many?
Tin (10)
helium-4 nucleus (4/2He)
high speed electron 0/-1 e-
What is the net effect of beta particle production?
to change a neutron to a proton (mass number isn’t changed, atomic number increases by 1)
high energy photon
gamma ray
What occurs for nuclides who’s neutron/proton ratios are too small?
position production
What have the same mass as electrons but with opposite charge? (antiparticle of electron)
What form high energy photons (gamma rays)= annihilation?
positron and electron collisions
one of the inner orbital electrons is captured by the nucleus
electron capture
time required for the number of nuclides to reach half the original value
half life
What gives particles very high velocities?
particle accelerators
What is Carbon-14 dating used for?
to date organisms that were once living
radioactive nuclides thatch be introduce into organisms in food or drugs and whose pathways can be traced by monitoring their radioactivity
radio tracers
combining two light nuclei to form a heavier, more stable nucleus (4H-> He in Sun)
splitting heavy nuclei into two nuclei with smaller mass numbers (bomb)
What are required to initiate fusion?
high temperatures
What are very close together in the nucleus?
What is the temperature of the sun?
4 x 10^7 K
What type of elements are in the center of the table?
transition metals
Which types of elements are at the bottom of the periodic table?
lanthanides and actinides

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