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Unit 2.1 Test Review-Answer Key
1. How did Mendeleev arrange the first periodic table?
By atomic mass
2. What did Mendeleev’s arrangement of the elements lead scientists to?
Predict the properties of unknown elements
3. Study the element key boxes for Tellurium (Te) and Iodine (I). Tellurium is in Group 18. Iodine
is in Group 17. How does the arrangement of Tellurium and Iodine contradict the overall
principle behind the organization of the periodic table?
Tellurium has a higher atomic mass than Iodine.
4. Magnesium is an alkaline earth metal. With which group of elements is magnesium most
reactive?
Non-metals
5. Using the chart below, calculate the average atomic mass and determine which element the
information is referring to.
Mass (amu)
20
21
22
Percent Abundance (%)
90.48
0.27
9.25
Average Atomic Mass Calculation:
20 x .9048 = 18.096
21 x .0027 = 0.0567
22 x .0925 = 2.035
Total Average Atom Mass = 20.188 a.m.u.
Element is Neon
6. List all the elements in the Halogen group.
Fluorine, chlorine, bromine, iodine, astatine
7. List all the elements in the Alkali Metals group.
Hydrogen, lithium, sodium, potassium, rubidium, cesium, francium
8. Why are the Noble Gases considered “inert” gases? List all the elements in this group.
-undergo fewest chemical reactions, low chemical reactivity
-helium, neon, argon, krypton, xenon, radon
9. List which elements are chemically similar to Beryllium. Explain why.
Magnesium, calcium, strontium, barium, radon are all chemically similar to
Beryllium. Elements in the same group have the same chemical properties.
10. Fill in the blank: Atoms are neutral when there is an equal number of protons and
electrons.
Name ____________________________________________________________________ Date __________________________
11. How many protons and neutrons are in one atom of
Protons = 17
Neutrons = 20
?
12. Which subatomic particle has the smallest mass? electron
13. Which group contains the most reactive elements? (give group name & number)
Group 1, Alkali Metals
14. Which group of elements will lose 2 electrons? (give group name & number)
Group 2, Alkaline Earth Metals
15. List all 4 parts to Dalton’s Atomic Theory. Which part is incorrect due to the discovery of
subatomic particles?
a. All elements are composed of tiny indivisible particles called atoms.
b. Atoms of the same element are identical.
c. Atoms of different elements can physically mix together or can chemically
combine with one another in definite ratios.
d. Chemical reactions occur when atoms are separated, joined, or rearranged.
“All elements are composed of tiny indivisible particles” is incorrect.
16. Which element contains 7 protons, 8 neutrons, and 7 electrons? nitrogen
6 protons
6 neutrons
6 protons
7 neutrons
6 protons
8 neutrons
8 protons
8 neutrons
17. Each diagram above represents the nucleus of a different atom. Circle the diagrams that
represent the nucleus of the same element.
18. Fill in the blank: Atoms of the same element all contain the same number of protons.
19. Phosphorus has an atomic number of 15 and a mass number of 31. How many protons,
neutrons, and electrons does a neutral atom of phosphorus contain?
a. Protons = 15
b. Neutrons = 16
c. Electrons = 15
20. Which part of the atom was discovered as a result of the Gold Foil experiment?
The nucleus
21. What charge does the nucleus have? positive
Name ____________________________________________________________________ Date __________________________
22. What surrounds the nucleus? What charge does this part of the atom contain?
Electrons surround the nucleus and have a negative charge.
23. Define isotopes.
Isotopes are atoms of the same element (same number of protons) with different
numbers of neutrons.
24. How do you know if a sample of matter contains only iron (Fe) atoms?
All atoms in the same contain 26 protons.
25. Where are metals located on the periodic table? On the left
26. Where are non-metals located on the periodic table? On the top right
27. Where are metalloids located on the periodic table? Along the stair step line
28. List whether the following elements are a metal, non-metal, or metalloid?
a. Germanium - metalloid
d. Boron - metalloid
b. Magnesium - metal
e. Chromium - metal
c. Bromine - nonmetal
f. Nitrogen - nonmetal
29. What is the charge of the proton? Neutron? Electron?
Proton – positive charge
Neutron – neutral/no charge
Electron - negative charge
30. What is the “Bohr Model”?
The Bohr model (sometimes called the planetary model) shows an atom in which
electrons orbit the nucleus in fixed paths.