Module 13 (Use the Periodic Chart to answer these questions. You will be able to use it on the test.) Flashcards
1a. define: model
a schematic description of a system that accounts for its known properties
1b. define: nucleus
the center of an atom, containing the protons and neutrons
1c. define: atomic number
the number of protons in an atom
1d. define: mass number
the sum of the number os neutons and protons in the nucleus of an atom
1e. define: isotopes
atoms with the same number of protons but different numbers of neutrons
1f. define: element
a collection of atoms that all have the same number of protons
1g. define: radioactive isotope
an atom with a neucleus that is not stable
1h. define: half-life
the time it takes for half of the original sample of a radioactive isotope to decay
- Order the three constituent parts of the atom in terms of their mass, from least massive to most massive.
electron, proton, neutron
- What force keeps the protons and neutrons in the nucleus? What causes this force?
the nuclear force; this force is caused by the exchange of pions between protons and/or neutrons
- What force keeps the electrons orbiting around the nucleus?
electromagnetic force
- What is an atom mostly made of?
mostly empty space
- An atom has an atomic number of 34. How many protons and electrons does it have? What is its symbol?
34 electrons and 34 protons; Se
- List the number of protons, electrons and neutrons for each of the following atoms:
a. Neon- 20 (neon’s chemical symbol is “Ne”)
b. 56Fe
c. 139La
d. 24Mg
a. 10 protons, 10 electrons, 10 neutrons
b. 26 protons, 26 electrons, 30 neutrons
c. 57 protons, 57 electrons, 82 neutrons
d. 12 protons, 12 electrons, 12 neutrons
- Two atoms are isotopes. The first has 18 protons and 20 neutrons. The second has 22 neutrons. How many protons does the second atom have?
the second atom also has 18 protons
- Which of the following atoms are isotopes?
112Cd, 112Sn, 120Xe, 124Sn, 40Ar, 120Sn
112Sn, 124Sn, 120Sn
- Draw what the Bohr model says and 16O atom would look like
look in answer key on page 32 #10
- Draw what the Bohr model says a 25Mg atom would look like.
look in answer key on page 32 #11
- What is the largest Bohr orbit in a uranium atom (the symbol for uranium is “U”), and how many electrons are in it?
the largest Bohr orbit is the fifth one, and there are 32 electrons in it
- Why is the strong nuclear force such a short-range force?
Since pions have a very short lifetime, the strong nuclear force can only act over very tiny distances.
- Determine the daughter products produced in the beta decay of the two radioactive isotopes shown below:
a. 98Tc b. 125I
a- 98Ru
b- 125Xe
- Determine the daughter products produced in the alpha decay of the two radioactive isotopes shown below:
a. 212Bi b. 224Ra
a- 208Tl
b- 220Rn
- 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
- 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, how many grams of 226Ra would be left after 3200 years?
2.5 grams
- The half-life of the man-made isotope 11C is 20 min. If a scientist makes 1 gram of 11C, how much will be left in one hour?
0.125 grams
- Why is radioactive dating unreliable in most situations?
Radioactive dating is usually unreliable because assumptions must be make as tok the original condition of the object. These assumptions are usually erroneous
- List the three types of radioactive particles discussed in this module in the order of their ability to travel through matter. Start with the particle that cannot pass through much matter before stopping, and end with the one that can pass through most matter before stopping.
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.
