Chem Quiz 9/6 Flashcards
what were cathode Ray Tubes used for?
Studying electrical discharge
How did cathode ray tubes work?
Applying a voltage across the electrodes, and evacuating air. Caused a spark which became a continuous beam
How did cathode ray tubes lead to the discovery of the electron?
Attraction/repulsion to magnetic fields
Who discovered the electron?
JJ Thomson
What did JJ Thomson’s experiment do?
Measure the force necessary to deflect the rays from the cathode stream
What did JJ Thomson’s results say the amount of deflection was dependent on?
Charge and mass of the particles
Who measured the charge of an electron? When?
Robert Millikan, 1909
What is the charge of an electron?
-1.60 x 10 ^-19
What is the mass of an electron?
9.10 x 10^-28 g
What was the early (1900s) model for atoms? Who created it, and what did it look like?
Plum pudding model, JJ thomson. Positive sphere of matter, electrons interspersed through it.
Who discovered the three types of radiation? What were they, and what were their charges
Ernest Rutherford- alpha (+), beta (-), gamma (unaffected by electric field)
What was Rutherford’s gold foil experiment? What did this prove?
Shooting alpha particles at gold foil and watching scatter (proved plum pudding model incorrect)
What was Rutherford’s model of the atom?
Small, dense nucleus with electrons outside. Atom is mostly empty space.
What were the 3 parts of Rutherford’s nuclear theory?
- Most of the atom’s mass and all of its positive charge were held in the nucleus
- Most of the atom’s volume is outside the nucleus, an empty space where there are just electrons
- The atom is completely neutral- #protons=#electrons
What is a neutron’s mass? Who discovered it?
1 amu, Sir James Chadwick
How are elements ordered on the periodic table?
Atomic #- number of protons
What is it called when a proton gains/loses an electron?
ion
What is it called when a proton gains an electron?
Anion
What is it called when a proton loses an electron?
Cation
What is different in isotopes?
Number of neutrons
Who discovered isotopes?
Frederick Soddy
How are isotopes identified?
Mass #s
How do you represent isotopes in writing?
Mass #
Chemical symbol
Atomic #
OR Chemical symbol/name- Mass #
How do you calculate average atomic mass?
(Fraction of isotope) x (Mass of isotope) Repeat for all isotopes
How are masses of atoms sorted to determine isotopes?
Mass spectometry- separates atoms by isotopes
Who is credited with creating the periodic table? What did they have in common?
Dmitri Mendeleev and Lothar Meyer
Both agreed elements should be arranged in order of increasing atomic weight
Who created the concept of atomic numbers? When?
Henrey Moseley, 2 years after Rutherford’s atomic model
What did Henry Moseley discover about each element?
Has a unique frequency
How did Henry Moseley arrange the elements?
Increasing atomic number,
Which elements are main group elements?
Groups 1-2A and 3A-8A (Any group with an A)
Which elements are transition elements?
Groups 3B- 2B (Any in low block, including bottom elements, which are inner transition elements)
Are transition or main group elements predictable based on their position?
Main group
Are metal oxides ionic or molecular?
Ionic
Are metal oxides ionic or molecular?
Molecular
Are most metal oxides acidic or basic?
Basic
Are most nonmetal oxides acidic or basic?
Acidic
Do metals tend to form anions or cations in aqueous solutions?
cations
Do nonmetals tend to form anions or cations in aqueous solutions?
anions or oxyanions
What is an oxyanion?
An anion that has at least one oxygen atom chemically bonded to a different element, eg sulfate/carbonate ions
What are some characteristics of metalloids?
Semi-conductors (Temperature dependent conductivity), often used in computers,
What are some metalloids?
Boron, silicon, arsenic, germanium, antimony, tellurium, astatine
What group are the alkali metals?
Group I (minus hydrogen)
What group are the alkaline earth metals?
Group 2
What groups are the transition metals?
Groups 3-12
What period are lathanoids?
What period is the actinide series?
What are the properties of alkali metals?
Soft, metallic solids. Only found in compounds in nature, not elemental sources. Low density, VERY reactive with water
What are the properties of Alkaline earth metals?
Harder than alkali metals, more dense, higher melting points, less reactive with water
What group are halogens?
7A, plus hydrogen
What elements are hydrogens?
FOHN
What group are the noble gases?
8A
What traits do noble gases have?
Nonmetals, inert, monatomic (Radon typically ignored bc radioactive)
What does isoelectronic mean?
2 different atoms with the same # of electrons
What are atoms hoping to achieve with their electrons?
Stability (Be inert, like noble gases)
Do metals gain or lose electrons to become more stable?
Lose (form cations)
Do nonmetals gain or lose electrons to become more stable?
Gain (form anions)
How do you measure the distance of a wavelength?
Peak to peak or trough to trough
What is the amplitude of a wave?
Its height
What determines the color of a wavelength?
Its frequency
What determines the brightness of a wavelength?
Its amplitude
What is white light?
All colors of light mixed together
What is color? How do we see it?
Where all wavelengths of light aren’t absorbed. It’s reflected
What is the frequency of a wave?
The amount of waves in a distance per unit of time
How are frequencies measured?
Hertz
Are frequency and wavelength proportional?
Yes, inversely
What do waves of energy depend on?
Amplitude and frequency
How fast do electromagnetic waves move?
Light speed- 3 x 10^8 m/s
Constructive interference
Similar waves combine to create a larger one
Destructive interference
Differing waves combine to cancel each other out
Wave diffraction
When waves travel through an opening in a barrier, they form bends around it.
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If there are 2, the waves interact changing their intensity (constructive and destructive)
Wavelengths, from shortest to longest
gamma, x rays, uv rays, visible light, infrared, microwaves, radiowaves
GXUVIMR
Radio waves
Audio signals, cell phone frequencoes, wi fi, mris
Microwaves
Heat food by interacting with water
Infrared
Heating from light fixture of electric stovetop, night vision goggles
Visible light
ROYGBIV
UV
Sunlight, tanning beds, UV lamps
X rays
Medical imaging
Gamma rays
Used for cancer treatment
