Unit 1: Atomic Structure

Question 1

the fundamental building blocks of matter

Answer 1

atoms

Question 2

subatomic particles that make up an atom

Answer 2

protons
neutrons
electrons

Question 3

particles in the nucleus

Answer 3

protons and neutrons

Question 4

define atomic number:

Answer 4

number of protons in an atom’s nucleus

Question 5

define atomic mass:

Answer 5

the combined mass of protons, neutrons, and electrons

Question 6

define atomic weight:

Answer 6

total number of protons and neutrons in the nucleus

Question 7

define Z number:

Answer 7

number of protons in an atom’s nucleus (another name for atomic number)

Question 8

define valence shell:

Answer 8

the outermost shell of an atom

Question 9

define valence electrons:

Answer 9

electrons located in the outermost shell

Question 10

stable atoms are electrically:

Answer 10

neutral

Question 11

define ionization:

Answer 11

addition or removal of an electron

Question 12

define the Octet rule:

Answer 12

the max number of electrons allowed in the valence shell of an atom is 8

Question 13

types of ionizing radiation:

Answer 13

particulate (alpha and beta)
electromagnetic (x-ray and gamma ray)

Question 14

define particulate radiation:

Answer 14

release of particles from the nucleus

Question 15

define alpha particles:

Answer 15

particles that have 2 protons, 2 neutrons, and 0 electrons

Question 16

atomic mass number of alpha particles and what kind of charge they contain:

Answer 16

4

+2 (double positive charge)

Question 17

energy, range, and origin of alpha particles:

Answer 17

4-7 MeV
1-10 cm in air
heavy radioactive nuclei

Question 18

define alpha emission:

Answer 18

throwing out neutrons or protons from the nucleus of a heavy atom

Question 19

define beta particles:

Answer 19

particles emitted from the nucleus that resemble electrons

Question 20

atomic mass number of beta particles and what kind of charge they contain:

Answer 20

0

-1 or +1 (neg. or pos. charged)

Question 21

energy, range, and origin of beta particles:

Answer 21

0-7 MeV
0-10 meters in air
radioactive nuclei

Question 22

Which form of particulate radiation can be stopped with a piece of paper? aluminum?

Answer 22

alpha; beta

Question 23

Which form of ionizing radiation is the most damaging? least?

Answer 23

alpha; beta

Question 24

list one thing that distinguishes a gamma ray from an x-ray:

Answer 24

origin

Question 25

x-rays originate in the:

Answer 25

electron shells

Question 26

gamma rays originate in the:

Answer 26

nucleus

Question 27

list two things that distinguish alpha and beta particles from x-rays:

Answer 27

1. particles originate in the nucleus 2. particles can be slowed down

Question 28

3 atomic forces that influence the behavior of the fundamental particles:

Answer 28

1. strong nuclear force 2. centripetal force 3. centrifugal force

Question 29

define strong nuclear force:

Answer 29

force of attraction between protons and neutrons (strongest attractive force)

Question 30

protons could not live in the nucleus without the force of attraction with the neutrons

Answer 30

true

Question 31

define centripetal force:

Answer 31

force between the nucleus and the electrons (neg. electrons are pulled towards the pos. nucleus)

Question 32

define centrifugal force:

Answer 32

force involving just the electrons where it pulls them away from the nucleus

Question 33

Types of energy:

Answer 33

1. nuclear binding energy 2. electron binding energy 3. kinetic energy of electrons

Question 34

define nuclear binding energy:

Answer 34

minimum energy required to disassemble the nucleus into its component parts

Question 35

define electron binding energy:

Answer 35

energy required to keep electrons within their orbital shells

Question 36

electron binding energy depends on what 2 factors?

Answer 36

distance from nucleus total number of electrons within the atom

Question 37

K-shell binding energies increase as:

Answer 37

atomic number (Z) increases

Question 38

as electron shell radius increases:

Answer 38

electron velocity increases

Question 39

electrons in outer orbits travel:

Answer 39

faster

Question 40

define radioactivity; what it's measured in:

Answer 40

the rate of decay of radioactive material Becquerels

Question 41

what makes an atom stable?

Answer 41

if the forces amongst the particles in the nucleus are balanced

Question 42

what makes an atom unstable?

Answer 42

if the forces in the nucleus are unbalanced; or if the nucleus has an excess of internal energy

Question 43

what does an unstable radioactive atom do to reach stability?

Answer 43

throw off protons or neutrons (nucleons) and particles, or by releasing energy

Question 44

define radioactive decay:

Answer 44

process where atoms with unstable nuclei emit excess energy

Question 45

define radionuclides:

Answer 45

nuclear arrangement resulting in radioactivity

Question 46

define radioactive half-life:

Answer 46

time required for an amount of radioactivity to be reduced to one-half of the original value represented as T1/2