The number of protons in an atom is different than the atom’s total mass.
Dmitri Mendeleev and Henry Moseley developed their periodic tables about forty years apart. During that time, many discoveries in chemistry were made.
Which fact was most likely discovered between the time of Mendeleev’s table and the time of Moseley’s table that helped Moseley develop his version?
Mendeleev observed that tellurium has chemical properties like other elements in its group, and he did not know that neutrons cause the greater atomic mass.
While developing his periodic table, Dmitri Mendeleev broke his own rule and placed the element tellurium before iodine in the group. He did this even though tellurium’s atomic mass was known to be greater than iodine’s. In his notes, Mendeleev stated that he expected tellurium to have a lower atomic mass than iodine. However, all measurements continue to show that tellurium has a greater atomic mass than iodine even though tellurium acts like it has a lower atomic mass.
What is the most likely reason that Mendeleev placed tellurium before iodine?
The modern periodic table has __ groups. (Write your answer as a number.)
1A, 3B, and 7A are examples of group _ on the periodic table.
the atomic mass
What is the property that is most similar among all elements across one whole period called?
number of valence electrons.
The elements in group 17 of the periodic table are all called halogens. All halogens have the same
which chemical properties they have
Elements in group 2 are all called alkaline earth metals. What is most similar about the alkaline earth metals?
bismuth and nitrogen, because they have the same number of valence electrons
Based on the information in the table, which two elements are most likely in the same group, and why?
Boron and carbon are likely together in one period because they have very close atomic numbers, while gallium and germanium are likely together in another period because they have very close atomic numbers.
Based on the information in the table, which elements are most likely in the same periods of the periodic table?
directly to the right
While looking at calcium (Ca) on the periodic table, a student needs to find an element with a greater atomic mass in the same period. Where should the student look?
While looking at xenon (Xe) on the periodic table, a student needs to find an element with a smaller atomic mass in the same group. Where should the student look?
This is how zirconium appears in the periodic table. Rounded to the nearest whole number, how many electrons are in an atom of zirconium?
This is how krypton appears in the periodic table. Rounded to the nearest whole number, how many protons are in an atom of krypton?
In an element’s square on the periodic table, the number with the greatest value represents the
combined number of neutrons and protons.
This is how sodium appears in the periodic table. The arrow is pointing to sodium’s
the atomic number
the number of protons
the number of electrons
This is how fluorine appears in the periodic table. What information does “9” give about an atom of fluorine? Check all that apply.
This is how osmium appears in the periodic table. Rounded to the nearest whole number, how many neutrons, on average, are in an atom of osmium?
Part of one row of the periodic table is shown. Which element’s atoms have the greatest average number of neutrons?