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CEM 141 Module 1 Questions & 100% Verified Correct Answers with complete solutions (Latest update
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CEM 141 Module 1their protons in the nucleus - ANS-What distinguishes one element from another?
an element composed of atoms w a new number of protons, diff # protons, unique set of
properties - ANS-What types of evidence might be used to conclude that you had isolated a new
element?
something nonreactive, bc they are identifiable based on properties - ANS-What types of
elements would be difficult to identify?
compounds are 2 or more types of elements which are chemically bonded
elements are a collection of atoms - ANS-What is the difference between an element and a
compound?
1) Elements are composed of small indivisible, indestructible particles called atoms.
2) All atoms of an element are identical and have the same mass and properties.
3) Atoms of a given element are different from atoms of other elements.
4) Compounds are formed by combinations of atoms of two or more elements.
5) Chemical reactions are due to the rearrangements of atoms; atoms (matter) are neither
created nor destroyed during a reaction. - ANS-Dalton's Atomic Theory
based on reacting different elements together to form compounds - ANS-How did Dalton Come
up w his theory?
greeks believed shape determined properties
dalton believed composition determined properties - ANS-How did dalton and the greeks differ?
Atoms of a given element are different from atoms of other elements. Y
Compounds are formed by combinations of atoms of two or more elements. Y
Chemical reactions are due to the rearrangements of atoms; atoms (matter) are neither created
nor destroyed during a reaction.Y - ANS-What is still true from Dalton's Atomic Theory?
discovered the electron - ANS-JJ Thompson
*glass tube consisted of 2 electrodes under very low pressure.
*High voltage is applied and the cathode emits particles that move toward anode
*Particle rays bend toward + platte
*mass of particles was about 2000 times lighter than H atom (1st evidence of particle smaller
than an atom)
, *type of metal that the cathode was made of did not affect the behavior of the ray, it did not
affect the type of particles (always had same madd to charge ratio
*provided evidence for atoms and substructure of atoms - ANS-Cathode Ray Tube Experiment
*Particles emerged from one disc (the cathode) and moved to the other (the anode)
*these particles could be deflected by electrical fields in a direction that would indicate they were
neg charged
*they carried the electric charge
*the metal that the cathode was made of did not affect the behavior of the ray
*all atoms contain electrons - ANS-Thompson's experiment showed
d - ANS-What is the evidence from Thomson's experiment that all atoms contain electrons?
a)The particles were attracted to the + electrode.
b)The particles were deflected by magnetic fields.
c)The particles were deflected by electrical fields.
d)The particles were identical regardless of the metal used for the cathode (where they were
emitted from).
Plum pudding
Atoms contain electrons "embedded" in a positively charged blob. positively charged body w
electrons embedded in it. - ANS-What was Thomson's model and what does it look like?
An alpha particle has 2 protons and 2 neutrons.
It is the nucleus of a helium atom. overall charge 2+ - ANS-What is an alpha particle?
Rutherford shot alpha particles from a radioactive source at a thin piece of gold foil. While most
went straight through, some of the aloha particles deflected indicating that there must be
something in the atom that blocks alpha particles. This was the nucleus. - ANS-Rutherford's
Experiment
most mass was concentrated in the. nucleus bc most alpha particles went straight through -
ANS-What did Rutherford conclude from this?
Small dense positive nucleus in the center of the atom.
Atom is mostly empty space
(Greeks said this)
this allows most atoms to go thru
some are deflectted due to electrostatic repulsion - ANS-What did Rutherford's experiment
show?
Planetary Model - ANS-What model did Rutherford make?
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