Define it!
A schematic description of a system that accounts for its known properties
Model
#1a SG
An element is a collection of atoms that all have the same number of protons
True
#1f SG
What force keeps the protons and neutrons in the nucleus?
The nuclear force (or strong force)
#3a SG
This 2-word term is defined as an atom with a nucleus that is not stable.
Radioactive isotope
#1g SG
What is an atom mostly made of?
Empty space
#5 SG
This hyphenated term is defined as the time it takes for half of the original sample of a radioactive isotope to decay.
Half-life
#1h SG
The center of an atom, containing the protons and neutrons
Nucleus
#1b SG
An analogy of the Bohr model of an atom made to scale: the 1st electron orbital is like the outside walls of a circular, major-league baseball stadium, and the nucleus is like a marble placed at the center of the stadium.
True
p. 315
What causes the nuclear force?
The exchange of pions between protons and/or neutrons
#3b SG
Why is radioactive dating unreliable in most situations?
Because assumptions must be made about the original condition of the object.
(These assumptions are usually wrong.)
#19 SG
What are the three constituent parts of the atom? List them in order, from least massive to most massive.
Electron, proton, and neutron
(electrons have significantly less mass, and the neutron is just slightly more massive than the proton)
#2 SG
Two atoms are isotopes. The first has 18 protons & 20 neutrons. The second has 22 neutrons. How many protons does the second atom have?
18 protons
(To be isotopes, the two atoms must have the same number of protons.)
#8 SG
The number of protons in an atom
Atomic number
#1c SG
In the Bohr model, a 16O atom would have 8 protons and 8 neutrons packed tightly in the nucleus, surrounded by two electron orbitals – the first orbit from the nucleus holding 2 electrons, and the second holding 6 electrons.
True
(“O” atoms have 8 protons in the chart, so we know there are 8 electrons; 2 electrons fit in the 1st Bohr orbit, & the remaining 6 electrons must go in the 2nd Bohr orbit, which can hold up to 8. The mass # – 16 – is the sum of protons & neutrons in the nucleus, so there are 8 neutrons)
#10 SG
What force keeps the electrons orbiting around the nucleus?
The electromagnetic force (or electroweak force)
(Electrons stay in orbit because they are attracted to the oppositely charged protons.)
#4 SG
A radioactive isotope goes through radioactive decay, but the isotope’s number of protons and neutrons does not change. What kind of radioactive decay occurred?
Gamma decay
(only gamma decay does not affect the number of neutrons & protons in a radioactive isotope)
#16 SG
An atom has an atomic number of 34. How many protons and electrons does it have?
34 protons & 34 electrons
(atomic number = # of protons in an atom, and atoms have the same # of electrons & protons; this is the atomic number for symbol Se)
#6a SG
Give the number of protons, electrons, and neutrons for a Lanthanum (139La) atom.
57 protons, 57 electrons, & 82 neutrons
(for symbol La, the chart shows atomic number 57, so we know the atom has 57 protons and an equal number of electrons. The mass # – 139 – is the sum of protons & neutrons in the nucleus, so there are 82 neutrons)
#7c SG
The sum of the numbers of neutrons and protons in the nucleus of an atom
Mass number
#1d SG
The three types of radioactive particles discussed in this module, in the order of their ability to travel through matter, are alpha particles, beta particles, and gamma rays.
True
(Alpha particles pass through the least amount of matter before stopping, beta particles are next, and gamma rays pass through the most matter before stopping.)
#20 SG
Why is the strong nuclear force such a short-range force?
Because pions have a very short lifetime
(Governed by the exchange of pions, the strong nuclear force can only act over very tiny distances since pions have a very short lifetime.)
#13 SG
What is the daughter product produced in the beta decay of radioactive isotope 98Tc?
98Ru
( 98Tc has 43 protons; with a mass of 98 (- 43 protons), there must be 55 neutrons. In beta decay, a neutron turns into a proton, resulting in an atom with 44 protons & 54 neutrons, or 98Ru.)
#14a SG
What is the symbol for an atom with an atomic number of 34?
Se
(the chart shows Se for Selenium atoms with atomic number 34)
#6b SG
Give the number of protons, electrons, and neutrons for a Magnesium (24Mg) atom.
12 protons, 12 electrons, & 12 neutrons
(for symbol Mg, the chart shows atomic number 12, so we know the atom has 12 protons and an equal number of electrons. The mass number – 24 – is the sum of protons & neutrons in the nucleus, so there are also 12 neutrons)
#7d SG
Atoms with the same number of protons but different numbers of neutrons
Isotopes
#1e SG
The half-life of the radioactive decay of 226Ra is 1,600 years. If a sample of 226Ra originally had a mass of 10 grams, 2.5 grams of 226Ra would be left after 3,200 years.
True
(In 1,600 years, the 10 grams cuts in half to 5 grams. In the next 1,600 years, that 5 grams cuts in half to 2.5 grams. That’s 2.5 grams in 3,200 years.)
#17 SG
Which of the following atoms are isotopes—112Cd, 112Sn, 120Xe, 124Sn, 40Ar, 120Sn?
112Sn, 124Sn, & 120Sn
(all isotopes must have the same symbol; the symbol – Sn – always has the same atomic # and # of protons, but its isotopes will have a different # of neutrons & different mass #s)
#9 SG
What is the daughter product produced in the alpha decay of radioactive isotope 212Bi?
208Tl
(212Bi has 83 protons; with a mass of 212 (-- 83 protons), there must be 129 neutrons. In alpha decay, the nucleus loses 2 protons & 2 neutrons, resulting in an atom with 81 protons & 127 neutrons, or 208Tl.)
#15a SG
List the number of protons, electrons, and neutrons for a Neon (Ne)-20 atom.
10 protons, 10 electrons, & 10 neutrons
(For symbol Ne, the chart shows atomic number 10, so we know the atom has 10 protons and an equal number of electrons. The mass number on the chart – 20 – is the sum of protons & neutrons in the nucleus, so there are also 10 neutrons.)
#7a SG
What is the daughter product produced in the alpha decay of radioactive isotope 224Ra?
220Rn
(224Ra has 88 protons; with a mass of 224 (--88 protons), there must be 136 neutrons. In alpha decay, the nucleus loses 2 protons & 2 neutrons, resulting in an atom with 86 protons and 134 neutrons, or 220Rn)
#15b SG
This is the simplest element in creation, with only one proton in every atom. It is a gas that is lighter than air, and it explodes when exposed to oxygen and a spark or flame.
Hydrogen
p. 320
In the Bohr model, a 25Mg atom would have 12 protons & 13 neutrons packed tightly in the nucleus, surrounded by two electron orbitals with equally spaced electrons – the first orbit from the nucleus holding 2 electrons, the second holding 10 electrons.
False
(“Mg” atoms have 12 protons in the chart, and there’s an equal # of electrons; 2 electrons fit in the 1st Bohr orbit, but ONLY 8 fit in the 2nd orbit. The final 2 need to move to the 3rd orbit, which can hold up to 18 electrons. The mass # – 25 – is the sum of protons & neutrons in the nucleus, so there are 13 neutrons.)
#11 SG
The half-life of the man-made isotope 11C is 20 minutes. If a scientist makes 1 gram of 11C, how much will be left in one hour?
0.125 grams
(In one hour, the 11C will go through 3 half-lives; 1 – 0.5 = 0.5 grams for the 1st half-life, 0.5 – 0.25 = 0.25 grams for the 2nd, and 0.25 – 0.125 = 0.125 grams for the 3rd)
#18 SG
What is the daughter product produced in the beta decay of radioactive isotope 125I?
125Xe
(125I has 53 protons; with a mass of 125 (--53 protons), there must be 72 neutrons. In beta decay, a neutron turns into a proton, resulting in an atom with 54 protons & 71 neutrons, or 125Xe.)
#14b SG
List the number of protons, electrons, and neutrons for an Iron (56Fe) atom.
26 protons, 26 electrons, & 30 neutrons
(for symbol Fe, the chart shows atomic number 26, so we know the atom has 26 protons and an equal number of electrons. The mass number – 56 – is the sum of protons & neutrons in the nucleus, so there are 30 neutrons.)
#7b SG
What is the largest Bohr orbit in a uranium atom (the symbol for uranium is “U”), and how many electrons are in it?
Uranium’s largest Bohr orbit is the 5th one, and it has 32 electrons in it
(With atomic #92, all uranium atoms have 92 protons & 92 electrons; 2 electrons fit in the 1st Bohr orbit, 8 in the 2nd; 18 in the 3rd, 32 in the 4th, and 32 in the 5th, which can hold up to 50 electrons)
#12 SG