Answer:
- The statement that is not true is: c) Sulfur is considered a metalloid
Step-by-step explanation:
To answer this kind of questions your best tool is a periodic table.
The periodic table shows the elements ordered by increasing atomic number (number of protons), in an arragement of rows and columns. In such arrangement, the elements appear classified as metals, non-metals, and metaloids.
Roughly metals are on the left side of the table, nonmetals are on the right side, and metalloids are a reduced group that are in a kind of step ladder dividing the metals and nonmetals.
With that, you can follow this procedure for each of the answer choices:
a) Barium is an alkali earth metal:
TRUE. Barium, Ba, has atomic number 56, is in the column (group) number 2, which is the group of the alkali earth metals.
b) Manganese is a transition metal:
TRUE. Manganese, Mn, has atomic number 25 and is in the column 7. The columns 3 through 12 enclose the transition metals. So, manganese is a transition metal.
c) Sulfur is considered a metalloid.
FALSE. Sulfur, S, has atomic number 16, is in the column 16, (right below oxygen) and is classified as a nonmetal.
d) Krypton is one of the noble gasses
TRUE. Krypton, Kr, has atomic number 36, and is in the column 18. This column includes all the noble gases, which are elements whose valence shells are complete (2 electrons in the case of He and 8 electrons in all the other cases).
This group is named noble gases because the elements have very low reactivity, so they are almos inert.
e) Iodine is a halogen
TRUE. Iodine, I, is the element with atomic number 53, and is in the column 17. This column includes all the halogens (F, Cl, Br, I, At, and the most recently discovered Ts).