Isotopes and Atomic Mass

Question 1

atomic mass unit (“amu” or “u”)

Answer 1

• mass unit is used on periodic table
• an element’s mass is based on the average of all of its natural naturally occurring isotopes

Question 2

isotopic abundance

Answer 2

• percentage of an element that exists as a given isotope
• Determined with a mass spectometer

Question 3

mass spectometer

Answer 3

Allows us to determine the mass

Question 4

strong nuclear force

Answer 4

• responsible for holding the nucleus of an atom
• nucleus is most stable when number of protons equals number of neutrons

Question 5

radiostopes

Answer 5

• atoms that contain an unstable nuclei
• “half life” refers to time for half the atoms to decay

Question 6

radioactive

Answer 6

spontaneously decay into smaller atoms and emit nuclear radiation in the form of tiny particles or energy

Question 7

isotopes

Answer 7

• A “version” of an element with the same number of protons, but different number of neutrons
• many elements have two or more naturally occurring stable isotopes
• Affects atomic mass

Question 8

types of radiation

Answer 8

• alpha
• beta
• gamma

Question 9

alpha

Answer 9

• positive
• same structure as helium
• Least energy
• Blocked by paper

Question 10

beta

Answer 10

• -ve particle identical to electron
• Blocked by aluminum

Question 11

gamma

Answer 11

-No mass
- high E
- blocked by lead

Question 12

calculate atomic mass of a element

Answer 12

multiply each mass by the percent converted to a decimal, then add

Question 13

applications

Answer 13

• smoke detectors (Am-241)
• thyroid cancer treatment (I-131)

Question 14

change in p+, e-, and n0

Answer 14

p+= different element
e-= ion formation
n0= isotopes